Message-ID:
 <SE1P216MB130362A9061EE36A6D46DAF2ED5A2@SE1P216MB1303.KORP216.PROD.OUTLOOK.COM>
Date: Mon, 26 Feb 2024 00:56:04 +0000
From: jackson.lee <jackson.lee@...psnmedia.com>
To: Nicolas Dufresne <nicolas@...fresne.ca>, "mchehab@...nel.org"
	<mchehab@...nel.org>, "linux-media@...r.kernel.org"
	<linux-media@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, Nas Chung <nas.chung@...psnmedia.com>
CC: lafley.kim <lafley.kim@...psnmedia.com>, "b-brnich@...com"
	<b-brnich@...com>
Subject: RE: [RESEND PATCH v0 3/5] wave5 : Support runtime suspend/resume.

Hello Nicolas

> 
> Le jeudi 22 février 2024 à 03:57 +0000, jackson.lee a écrit :
> > >
> > > > Le mercredi 21 février 2024 à 02:27 +0000, jackson.lee a écrit :
> > > > > Hello Nicolas
> > > > >
> > > > >
> > > > > Thanks for your comment
> > > > >
> > > > > > Le mardi 20 février 2024 à 05:12 +0000, jackson.lee a écrit :
> > > > > > > A pause is common state for media player, but our VPU could
> > > > > > > trigger an
> > > > > > interrupt regardless of a player state.
> > > > > > > So at a pause state if a power turns off, our driver becomes
> > > > > > > hang-
> > > up.
> > > > > > > I think power on/off should be controlled in the open/close
> > > function.
> > > > > >
> > > > > > Please, avoid top posting, this breaks the discussion completely.
> > > > > > Walk through the comments, and reply to them underneath so we
> > > > > > can have a proper discussion.
> > > > > >
> > > > > > In our experience, and with the rework of the driver we did
> > > > > > during
> > > > > > up- streaming, there is no more un-solicited IRQ. The way the
> > > > > > driver state machine has been built, when the m2m framework is
> > > > > > idle (no jobs are active or pending), it means the firmware is
> > > > > > stalled, waiting on some application action. Combined with a
> > > > > > timer of course, so we don't actively suspend/resume, this
> > > > > > seems adequate place to do power management. If that
> > > > > > application action never occurred passed a
> > > > decent delay, we can suspend.
> > > > > > Later on, user actions like qbuf, will lead to
> > > > > > device_run() to be called again, and it would be a good place
> > > > > > to
> > > > resume it.
> > > > >
> > > > > The above comment means like the below ?
> > > > > The wave5_vpu_dec_finish_decode is called by IRQ if there is a
> > > > > decoded
> > > > frame.
> > > > > And at the end of the function, if there is no data queued,
> > > > v4l2_m2m_job_finish is called.
> > > > > You means suspend is called in that function and if app feeds
> > > > > new data into v4l2 driver, the device_run then is called, In the
> > > > > device_run,
> > > > resume is called.
> > > >
> > > > That is the general idea. (Note that we don't forcefully suspect,
> > > > for this type of HW, we should configure a delay. Just saying in
> > > > case someone miss- interpret what was written here)
> > > >
> > > > >
> > > > >
> > > > > I have a question,
> > > > > If app is paused or resumed , the v4l2's vidioc_decoder_cmd is
> > > > > always
> > > > called ?
> > > >
> > > > There is no indication if an app is paused / resumed. Runtime PM
> > > > in fact should not depend on application actions in general. In
> > > > the case of V4L2, most driver will configure a delay (like 5
> > > > seconds). If the driver has been idle (no pending work, no jobs)
> > > > withing that delay, it will auto suspend. Then whenever new
> > > > activity comes, like a QBUF, we
> > > resume.
> > > >
> >
> > Below is a pseudo code for configuring a delay for the Run time
> suspend/resume.
> > The logic you are saying means the below ?
> >
> > Driver_probe
> > {
> >  	pm_runtime_set_autosuspend_delay(vpu->dev, 100);
> > 	pm_runtime_use_autosuspend(vpu->dev);
> > 	pm_runtime_enable(vpu->dev);
> >
> > }
> >
> > Device_run
> > {
> >
> > 	pm_runtime_resume_and_get(ctx->dev->dev);
> > }
> >
> >
> > Finish_job
> > {
> > 	pm_runtime_mark_last_busy(vpu->dev);
> > 	pm_runtime_put_autosuspend(vpu->dev);
> >
> > }
> >
> 
> This is aligned with what I had in mind. There will be few cases were
> you'll need to ensure the hardware is active outside of this (open() and
> close() are examples), but otherwise this should in my perception gives
> the best power saving. And finally, the delay might need tuning, at first
> 100ms seems a bit low, the delay needs to be balanced against the suspend
> cost.
> 
> Nicolas
> 

Thanks for your comment.

Thanks
Jackson







> >
> >
> > Thanks.
> > Jackson
> >
> > >
> > > The delay means a timer, so there is no input for 5 secs, then
> > > timeout callback is called, And suspend is set, if new activity
> > > comes, the device is resumed again ?
> > > My understanding is correct ?
> > >
> >
> >
> > >
> > >
> > > > Nicolas
> > > >
> > > > >
> > > > > Thanks.
> > > > >
> > > > >
> > > > > > There is of course other places where you'll have to make sure
> > > > > > the hardware is resumed, like on close, as you want to remove
> > > > > > the
> > > instance.
> > > > > > There is also small queries here and there that need to be
> > > > > > surrounded with resume/put, but with the redesign, most of the
> > > > > > HW access now take place inside device_run() only.
> > > > > >
> > > > > > Open/Close is not invalid, but it has a lot of issues, as any
> > > > > > random application can endup disabling the kernel ability to
> > > > > > save
> > > power.
> > > > > > Personally, I think we should at least give it a try, and
> > > > > > document valid reason not to do so if we find hardware issues.
> > > > > > Otherwise, this sounds like all we care is ticking the box
> > > > > > "this driver has runtime PM" without actually caring about
> effective power saving.
> > > > > >
> > > > > > Nicolas
> > > > > >
> > > > > > >
> > > > > > > Thanks.
> > > > > > >
> > > > > > > > Le lundi 19 février 2024 à 04:04 +0000, jackson.lee a écrit :
> > > > > > > > > Hi Nicolas
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > > This seems very unnatural. We do the get() in
> > > > > > > > > > "start_streaming()", but the
> > > > > > > > > > put() is only done when the device is closed, or when
> > > > > > > > > > the driver is removed. As this is not balanced, you
> > > > > > > > > > seem to have to check the suspended condition all over
> the place.
> > > > > > > > > >
> > > > > > > > > > I think we could aim for
> > > > > > > > > > start_streaming()/stop_streaming()
> > > > > > > > > > for your get/put placement. At least they will be
> > > > > > > > > > bound to an entirely balanced
> > > > > > > > API.
> > > > > > > > > > But then, a media player in paused sate will prevent
> > > > > > > > > > that device from being suspended.
> > > > > > > > > >
> > > > > > > > > > If the HW is capable of preserving enough state, and
> > > > > > > > > > From the short doc I have it gives me the impression
> > > > > > > > > > it can preserve that, I'd suggest to follow what
> > > > > > > > > > hantro driver is doing. What is does is that it will
> > > > > > > > > > do get() in device_run(), and put() whenever the job
> > > > > > > > > > completes. This driver has been designed so when there
> > > > > > > > > > is no job, it means the firmware is currently idle and
> looking for more work.
> > > > > > > > > > So it seems like the perfect moment to
> > > > > > do suspend it.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > Thanks your comment,
> > > > > > > > >
> > > > > > > > > Currently they are not balanced, If we puts "the put
> functon"
> > > > > > > > > into the stop_streaming, our hw is stalled
> > > > > > > > until doing wake-up command, so our v4l2 device become block.
> > > > > > > > > so I'd like to update the below instead of calling get
> > > > > > > > > at the
> > > > > > > > start_streaming function.
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > @@ -1867,6 +1868,13 @@ static int
> > > > > > > > > wave5_vpu_open_dec(struct file
> > > > > > > > > *filp)
> > > > > > > > >
> > > > > > > > >         wave5_vdi_allocate_sram(inst->dev);
> > > > > > > > >
> > > > > > > > > +       err = pm_runtime_resume_and_get(inst->dev->dev);
> > > > > > > > > +       if (err) {
> > > > > > > > > +               dev_err(inst->dev->dev, "decoder runtime
> > > > > > > > > + resume
> > > > > > > > failed %d\n", err);
> > > > > > > > > +               ret = -EINVAL;
> > > > > > > > > +               goto cleanup_inst;
> > > > > > > > > +       }
> > > > > > > > > +
> > > > > > > > >         return 0;
> > > > > > > >
> > > > > > > > I guess we need to discuss the power management strategy
> > > > > > > > for this
> > > > > > device.
> > > > > > > > If you do resume_and_get() in open(), and then put in
> > > > > > > > close(), that seems balanced. But in term of power saving,
> > > > > > > > it might not be very strong. If you have a media player
> > > > > > > > that is set to pause and then placed in the background,
> > > > > > > > you still keep the IP running. This is extremely common,
> > > > > > > > since application cannot close their device without
> > > > > > > > loosing the reference frames, and thus having to do extra
> > > > > > > > work on resume to seek back to the previous sync point and
> > > > > > > > drop
> > > > > > unneeded frames.
> > > > > > > >
> > > > > > > > It seems like the whole point of asking the firmware to
> > > > > > > > save the state and suspend is to be able to do so while
> > > > > > > > there is meaningful sate in the firt place.
> > > > > > > > If we are to suspend only when there is no meaningful
> > > > > > > > state, we could just free all resources and power it off
> completely.
> > > > > > > > (This is just for illustration, its probably to slow to
> > > > > > > > boot the firmware at
> > > > > > > > runtime)
> > > > > > > >
> > > > > > > >
> > > > > > > > I understand you suffered lockup with a start_streaming()
> > > > > > > > for resume_and_get(), and stop_streaming() for put(), this
> > > > > > > > may simply indicate that some hardware access are needed
> > > > > > > > between these two. Can you write down a power management
> > > > > > > > plan that would effectively save power in common use cases
> > > > > > > > ? We can certainly help in refactoring the
> > > > > > code to make that happen.
> > > > > > > >
> > > > > > > > Nicolas
> > > > > > > >
> > > > > > > > >
> > > > > > > > > > Le mercredi 31 janvier 2024 à 10:30 +0900, jackson.lee
> > > > > > > > > > a
> > > > écrit :
> > > > > > > > > > > There are two device run-time PM callbacks defined
> > > > > > > > > > > in 'struct
> > > > > > > > > > dev_pm_ops'
> > > > > > > > > > > int (*runtime_suspend)(struct device *dev); int
> > > > > > > > > > > (*runtime_resume)(struct device *dev);
> > > > > > > > > >
> > > > > > > > > > I wonder how useful is it to teach everyone what the
> > > > > > > > > > generic 'struct dev_pm_ops'
> > > > > > > > > > contains. Perhaps you simply wanted that this patch
> > > > > > > > > > implement both suspend and resume ops ?
> > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Signed-off-by: Jackson Lee
> > > > > > > > > > > <jackson.lee@...psnmedia.com>
> > > > > > > > > > > Signed-off-by: Nas Chung <nas.chung@...psnmedia.com>
> > > > > > > > > > > ---
> > > > > > > > > > >  .../platform/chips-media/wave5/wave5-hw.c     |  5 +-
> > > > > > > > > > >  .../chips-media/wave5/wave5-vpu-dec.c         |  9 +++
> > > > > > > > > > >  .../chips-media/wave5/wave5-vpu-enc.c         |  9 +++
> > > > > > > > > > >  .../platform/chips-media/wave5/wave5-vpu.c    | 68
> > > > > > > > +++++++++++++++++++
> > > > > > > > > > >  .../platform/chips-media/wave5/wave5-vpuapi.c |  7
> > > > > > > > > > > ++ .../media/platform/chips-media/wave5/wave5.h  |
> > > > > > > > > > > 3 +
> > > > > > > > > > >  6 files changed, 99 insertions(+), 2 deletions(-)
> > > > > > > > > > >
> > > > > > > > > > > diff --git
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-hw.
> > > > > > > > > > > c
> > > > > > > > > > > b/drivers/media/platform/chips-media/wave5/wave5-hw.
> > > > > > > > > > > c index 8ad7f3a28ae1..8aade5a38439 100644
> > > > > > > > > > > ---
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-hw.
> > > > > > > > > > > c
> > > > > > > > > > > +++ b/drivers/media/platform/chips-media/wave5/wave5-
> hw.
> > > > > > > > > > > +++ c
> > > > > > > > > > > @@ -503,6 +503,7 @@ int
> > > > > > > > > > > wave5_vpu_build_up_dec_param(struct
> > > > > > > > > > > vpu_instance
> > > > > > > > > > *inst,
> > > > > > > > > > >  	/* This register must be reset explicitly */
> > > > > > > > > > >  	vpu_write_reg(inst->dev, W5_CMD_EXT_ADDR, 0);
> > > > > > > > > > >  	vpu_write_reg(inst->dev, W5_CMD_NUM_CQ_DEPTH_M1,
> > > > > > > > > > > (COMMAND_QUEUE_DEPTH - 1));
> > > > > > > > > > > +	vpu_write_reg(inst->dev, W5_CMD_ERR_CONCEAL, 0);
> > > > > > > > > >
> > > > > > > > > > In some way, the relation between suspend and this
> > > > > > > > > > register write is not obvious. If its not related,
> > > > > > > > > > please do this in its
> > > > > > own patch.
> > > > > > > > > > Otherwise you want to explain why you needed this
> > > > > > > > > > (possibly just in the commit message).
> > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >  	ret = send_firmware_command(inst,
> > > > > > > > > > > W5_CREATE_INSTANCE, true, NULL,
> > > > > > > > > > NULL);
> > > > > > > > > > >  	if (ret) {
> > > > > > > > > > > @@ -1075,8 +1076,8 @@ int wave5_vpu_re_init(struct
> > > > > > > > > > > device *dev, u8 *fw,
> > > > > > > > > > size_t size)
> > > > > > > > > > >  	return setup_wave5_properties(dev);  }
> > > > > > > > > > >
> > > > > > > > > > > -static int wave5_vpu_sleep_wake(struct device *dev,
> > > > > > > > > > > bool i_sleep_wake,
> > > > > > > > > > const uint16_t *code,
> > > > > > > > > > > -				size_t size)
> > > > > > > > > > > +int wave5_vpu_sleep_wake(struct device *dev, bool
> > > > > > > > > > > +i_sleep_wake, const
> > > > > > > > > > uint16_t *code,
> > > > > > > > > > > +			 size_t size)
> > > > > > > > > > >  {
> > > > > > > > > > >  	u32 reg_val;
> > > > > > > > > > >  	struct vpu_buf *common_vb; diff --git
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > -dec
> > > > > > > > > > > .c
> > > > > > > > > > > b/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > -dec .c index ef227af72348..328a7a8f26c5 100644
> > > > > > > > > > > ---
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > -dec
> > > > > > > > > > > .c
> > > > > > > > > > > +++ b/drivers/media/platform/chips-media/wave5/wave5
> > > > > > > > > > > +++ -vpu
> > > > > > > > > > > +++ -d
> > > > > > > > > > > +++ ec.c
> > > > > > > > > > > @@ -5,6 +5,7 @@
> > > > > > > > > > >   * Copyright (C) 2021-2023 CHIPS&MEDIA INC
> > > > > > > > > > >   */
> > > > > > > > > > >
> > > > > > > > > > > +#include <linux/pm_runtime.h>
> > > > > > > > > > >  #include "wave5-helper.h"
> > > > > > > > > > >
> > > > > > > > > > >  #define VPU_DEC_DEV_NAME "C&M Wave5 VPU decoder"
> > > > > > > > > > > @@ -1387,9 +1388,17 @@ static int
> > > > > > > > > > > wave5_vpu_dec_start_streaming(struct
> > > > > > > > > > > vb2_queue *q, unsigned int count
> > > > > > > > > > >
> > > > > > > > > > >  	if (q->type ==
> V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> > > > > > > > > > > &&
> > > > > > > > > > > inst-
> > > > > > > > > state
> > > > > > > > > > > ==
> > > > > > > > > > VPU_INST_STATE_NONE) {
> > > > > > > > > > >  		struct dec_open_param open_param;
> > > > > > > > > > > +		int err = 0;
> > > > > > > > > > >
> > > > > > > > > > >  		memset(&open_param, 0, sizeof(struct
> > > > dec_open_param));
> > > > > > > > > > >
> > > > > > > > > > > +		err = pm_runtime_resume_and_get(inst-
> >dev->dev);
> > > > > > > > > > > +		if (err) {
> > > > > > > > > > > +			dev_err(inst->dev->dev, "decoder
> runtime
> > > > resume
> > > > > > > > > > failed %d\n", err);
> > > > > > > > > > > +			ret = -EINVAL;
> > > > > > > > > > > +			goto return_buffers;
> > > > > > > > > > > +		}
> > > > > > > > > > > +
> > > > > > > > > > >  		ret =
> wave5_vpu_dec_allocate_ring_buffer(inst);
> > > > > > > > > > >  		if (ret)
> > > > > > > > > > >  			goto return_buffers; diff --git
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > -enc
> > > > > > > > > > > .c
> > > > > > > > > > > b/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > -enc .c index 761775216cd4..ff73d69de41c 100644
> > > > > > > > > > > ---
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > -enc
> > > > > > > > > > > .c
> > > > > > > > > > > +++ b/drivers/media/platform/chips-media/wave5/wave5
> > > > > > > > > > > +++ -vpu
> > > > > > > > > > > +++ -e
> > > > > > > > > > > +++ nc.c
> > > > > > > > > > > @@ -5,6 +5,7 @@
> > > > > > > > > > >   * Copyright (C) 2021-2023 CHIPS&MEDIA INC
> > > > > > > > > > >   */
> > > > > > > > > > >
> > > > > > > > > > > +#include <linux/pm_runtime.h>
> > > > > > > > > > >  #include "wave5-helper.h"
> > > > > > > > > > >
> > > > > > > > > > >  #define VPU_ENC_DEV_NAME "C&M Wave5 VPU encoder"
> > > > > > > > > > > @@ -1387,9 +1388,17 @@ static int
> > > > > > > > > > > wave5_vpu_enc_start_streaming(struct
> > > > > > > > > > > vb2_queue *q, unsigned int count
> > > > > > > > > > >
> > > > > > > > > > >  	if (inst->state == VPU_INST_STATE_NONE && q-
> >type
> > > > > > > > > > > ==
> > > > > > > > > > V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
> > > > > > > > > > >  		struct enc_open_param open_param;
> > > > > > > > > > > +		int err = 0;
> > > > > > > > > > >
> > > > > > > > > > >  		memset(&open_param, 0, sizeof(struct
> > > > enc_open_param));
> > > > > > > > > > >
> > > > > > > > > > > +		err = pm_runtime_resume_and_get(inst-
> >dev->dev);
> > > > > > > > > > > +		if (err) {
> > > > > > > > > > > +			dev_err(inst->dev->dev, "encoder
> runtime
> > > > resume
> > > > > > > > > > failed %d\n", err);
> > > > > > > > > > > +			ret = -EINVAL;
> > > > > > > > > > > +			goto return_buffers;
> > > > > > > > > > > +		}
> > > > > > > > > > > +
> > > > > > > > > > >  		wave5_set_enc_openparam(&open_param,
> inst);
> > > > > > > > > > >
> > > > > > > > > > >  		ret = wave5_vpu_enc_open(inst,
> &open_param);
> > > > diff --
> > > > > > > > git
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > .c
> > > > > > > > > > > b/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > .c index 0d90b5820bef..f81409740a56 100644
> > > > > > > > > > > ---
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-vpu
> > > > > > > > > > > .c
> > > > > > > > > > > +++ b/drivers/media/platform/chips-media/wave5/wave5
> > > > > > > > > > > +++ -vpu
> > > > > > > > > > > +++ .c
> > > > > > > > > > > @@ -10,6 +10,7 @@
> > > > > > > > > > >  #include <linux/clk.h>
> > > > > > > > > > >  #include <linux/firmware.h>  #include
> > > > > > > > > > > <linux/interrupt.h>
> > > > > > > > > > > +#include <linux/pm_runtime.h>
> > > > > > > > > > >  #include "wave5-vpu.h"
> > > > > > > > > > >  #include "wave5-regdefine.h"
> > > > > > > > > > >  #include "wave5-vpuconfig.h"
> > > > > > > > > > > @@ -117,6 +118,65 @@ static int
> > > > > > > > > > > wave5_vpu_load_firmware(struct device
> > > > > > > > > > *dev, const char *fw_name,
> > > > > > > > > > >  	return 0;
> > > > > > > > > > >  }
> > > > > > > > > > >
> > > > > > > > > > > +static __maybe_unused int wave5_pm_suspend(struct
> > > > > > > > > > > +device
> > > > > > > > > > > +*dev)
> > > > > > {
> > > > > > > > > > > +	struct vpu_device *vpu = dev_get_drvdata(dev);
> > > > > > > > > > > +
> > > > > > > > > > > +	if (pm_runtime_suspended(dev))
> > > > > > > > > > > +		return 0;
> > > > > > > > > > > +
> > > > > > > > > > > +	wave5_vpu_sleep_wake(dev, true, NULL, 0);
> > > > > > > > > > > +	clk_bulk_disable_unprepare(vpu->num_clks,
> > > > > > > > > > > +vpu->clks);
> > > > > > > > > > > +
> > > > > > > > > > > +	return 0;
> > > > > > > > > > > +}
> > > > > > > > > > > +
> > > > > > > > > > > +static __maybe_unused int wave5_pm_resume(struct
> > > > > > > > > > > +device
> > > > *dev) {
> > > > > > > > > > > +	struct vpu_device *vpu = dev_get_drvdata(dev);
> > > > > > > > > > > +	int ret = 0;
> > > > > > > > > > > +
> > > > > > > > > > > +	wave5_vpu_sleep_wake(dev, false, NULL, 0);
> > > > > > > > > > > +	ret = clk_bulk_prepare_enable(vpu->num_clks,
> vpu-
> > > > > clks);
> > > > > > > > > > > +	if (ret) {
> > > > > > > > > > > +		dev_err(dev, "Enabling clocks,
> fail: %d\n",
> > > > ret);
> > > > > > > > > > > +		return ret;
> > > > > > > > > > > +	}
> > > > > > > > > > > +
> > > > > > > > > > > +	return ret;
> > > > > > > > > > > +}
> > > > > > > > > > > +
> > > > > > > > > > > +static __maybe_unused int wave5_suspend(struct
> > > > > > > > > > > +device
> > > > > > > > > > > +*dev)
> > > > {
> > > > > > > > > > > +	struct vpu_device *vpu = dev_get_drvdata(dev);
> > > > > > > > > > > +	struct vpu_instance *inst;
> > > > > > > > > > > +
> > > > > > > > > > > +	list_for_each_entry(inst, &vpu->instances, list)
> > > > > > > > > > > +		v4l2_m2m_suspend(inst->v4l2_m2m_dev);
> > > > > > > > > > > +
> > > > > > > > > > > +	return pm_runtime_force_suspend(dev); }
> > > > > > > > > > > +
> > > > > > > > > > > +static __maybe_unused int wave5_resume(struct
> > > > > > > > > > > +device
> > > > > > > > > > > +*dev)
> > > > {
> > > > > > > > > > > +	struct vpu_device *vpu = dev_get_drvdata(dev);
> > > > > > > > > > > +	struct vpu_instance *inst;
> > > > > > > > > > > +	int ret = 0;
> > > > > > > > > > > +
> > > > > > > > > > > +	ret = pm_runtime_force_resume(dev);
> > > > > > > > > > > +	if (ret < 0)
> > > > > > > > > > > +		return ret;
> > > > > > > > > > > +
> > > > > > > > > > > +	list_for_each_entry(inst, &vpu->instances, list)
> > > > > > > > > > > +		v4l2_m2m_resume(inst->v4l2_m2m_dev);
> > > > > > > > > > > +
> > > > > > > > > > > +	return ret;
> > > > > > > > > > > +}
> > > > > > > > > >
> > > > > > > > > > The functions wave5_suspend() and wave5_resume() are
> > > > > > > > > > not just "maybe_unsued" but actually never used. What
> > > > > > > > > > was the
> > > > intention ?
> > > > > > > > > > Considering the usage of __maybe_unused has been such
> > > > > > > > > > a bad friend for this one, could you instead bracket
> > > > > > > > > > the functions with an
> > > > > > > > explicit ?
> > > > > > > > > >
> > > > > > > > > > #ifdef CONFIG_PM
> > > > > > > > > > #endif
> > > > > > > > > >
> > > > > > > > > > This way the compiler will have a word if you
> > > > > > > > > > implement something that you forgot to actually use.
> > > > > > > > > >
> > > > > > > > > > > +
> > > > > > > > > > > +static const struct dev_pm_ops wave5_pm_ops = {
> > > > > > > > > > > +	SET_RUNTIME_PM_OPS(wave5_pm_suspend,
> > > > > > > > > > > +wave5_pm_resume,
> > > > > > > > NULL) };
> > > > > > > > > > > +
> > > > > > > > > > >  static int wave5_vpu_probe(struct platform_device
> > > > > > > > > > > *pdev)
> > > {
> > > > > > > > > > >  	int ret;
> > > > > > > > > > > @@ -232,6 +292,10 @@ static int
> > > > > > > > > > > wave5_vpu_probe(struct platform_device
> > > > > > > > > > *pdev)
> > > > > > > > > > >  		 (match_data->flags & WAVE5_IS_DEC) ?
> > > > "'DECODE'" : "");
> > > > > > > > > > >  	dev_info(&pdev->dev, "Product Code:      0x%x\n",
> dev-
> > > > > > > > > product_code);
> > > > > > > > > > >  	dev_info(&pdev->dev, "Firmware Revision: %u\n",
> > > > > > > > > > > fw_revision);
> > > > > > > > > > > +
> > > > > > > > > > > +	pm_runtime_enable(&pdev->dev);
> > > > > > > > > > > +	wave5_vpu_sleep_wake(&pdev->dev, true, NULL, 0);
> > > > > > > > > > > +
> > > > > > > > > > >  	return 0;
> > > > > > > > > > >
> > > > > > > > > > >  err_enc_unreg:
> > > > > > > > > > > @@ -254,6 +318,9 @@ static int
> > > > > > > > > > > wave5_vpu_remove(struct platform_device
> > > > > > > > > > > *pdev)  {
> > > > > > > > > > >  	struct vpu_device *dev =
> > > > > > > > > > > dev_get_drvdata(&pdev->dev);
> > > > > > > > > > >
> > > > > > > > > > > +	pm_runtime_put_sync(&pdev->dev);
> > > > > > > > > > > +	pm_runtime_disable(&pdev->dev);
> > > > > > > > > > > +
> > > > > > > > > > >  	mutex_destroy(&dev->dev_lock);
> > > > > > > > > > >  	mutex_destroy(&dev->hw_lock);
> > > > > > > > > > >  	clk_bulk_disable_unprepare(dev->num_clks,
> > > > > > > > > > > dev->clks);
> > > > @@
> > > > > > > > > > > -
> > > > > > > > 281,6
> > > > > > > > > > > +348,7 @@ static struct platform_driver
> > > > > > > > > > > +wave5_vpu_driver = {
> > > > > > > > > > >  	.driver = {
> > > > > > > > > > >  		.name = VPU_PLATFORM_DEVICE_NAME,
> > > > > > > > > > >  		.of_match_table =
> of_match_ptr(wave5_dt_ids),
> > > > > > > > > > > +		.pm = &wave5_pm_ops,
> > > > > > > > > > >  		},
> > > > > > > > > > >  	.probe = wave5_vpu_probe,
> > > > > > > > > > >  	.remove = wave5_vpu_remove, diff --git
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-
> vpuapi.
> > > > > > > > > > > c
> > > > > > > > > > > b/drivers/media/platform/chips-media/wave5/wave5-
> vpuapi.
> > > > > > > > > > > c index 1a3efb638dde..f1f8e4fc8474 100644
> > > > > > > > > > > ---
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5-
> vpuapi.
> > > > > > > > > > > c
> > > > > > > > > > > +++ b/drivers/media/platform/chips-media/wave5/wave5
> > > > > > > > > > > +++ -vpu
> > > > > > > > > > > +++ ap
> > > > > > > > > > > +++ i.c
> > > > > > > > > > > @@ -6,6 +6,7 @@
> > > > > > > > > > >   */
> > > > > > > > > > >
> > > > > > > > > > >  #include <linux/bug.h>
> > > > > > > > > > > +#include <linux/pm_runtime.h>
> > > > > > > > > > >  #include "wave5-vpuapi.h"
> > > > > > > > > > >  #include "wave5-regdefine.h"
> > > > > > > > > > >  #include "wave5.h"
> > > > > > > > > > > @@ -232,6 +233,9 @@ int wave5_vpu_dec_close(struct
> > > > > > > > > > > vpu_instance *inst,
> > > > > > > > > > > u32 *fail_res)
> > > > > > > > > > >
> > > > > > > > > > >  	wave5_vdi_free_dma_memory(vpu_dev,
> > > > > > > > > > > &p_dec_info->vb_task);
> > > > > > > > > > >
> > > > > > > > > > > +	if (!pm_runtime_suspended(inst->dev->dev))
> > > > > > > > > > > +		pm_runtime_put_sync(inst->dev->dev);
> > > > > > > > > > > +
> > > > > > > > > > >  unlock_and_return:
> > > > > > > > > > >  	mutex_unlock(&vpu_dev->hw_lock);
> > > > > > > > > > >
> > > > > > > > > > > @@ -734,6 +738,9 @@ int wave5_vpu_enc_close(struct
> > > > > > > > > > > vpu_instance *inst,
> > > > > > > > > > > u32 *fail_res)
> > > > > > > > > > >
> > > > > > > > > > >  	wave5_vdi_free_dma_memory(vpu_dev,
> > > > > > > > > > > &p_enc_info->vb_task);
> > > > > > > > > > >
> > > > > > > > > > > +	if (!pm_runtime_suspended(inst->dev->dev))
> > > > > > > > > > > +		pm_runtime_put_sync(inst->dev->dev);
> > > > > > > > > >
> > > > > > > > > > This seems very unnatural. We do the get() in
> > > > > > > > > > "start_streaming()", but the
> > > > > > > > > > put() is only done when the device is closed, or when
> > > > > > > > > > the driver is removed. As this is not balanced, you
> > > > > > > > > > seem to have to check the suspended condition all over
> the place.
> > > > > > > > > >
> > > > > > > > > > I think we could aim for
> > > > > > > > > > start_streaming()/stop_streaming()
> > > > > > > > > > for your get/put placement. At least they will be
> > > > > > > > > > bound to an entirely balanced
> > > > > > > > API.
> > > > > > > > > > But then, a media player in paused sate will prevent
> > > > > > > > > > that device from being suspended.
> > > > > > > > > >
> > > > > > > > > > If the HW is capable of preserving enough state, and
> > > > > > > > > > From the short doc I have it gives me the impression
> > > > > > > > > > it can preserve that, I'd suggest to follow what
> > > > > > > > > > hantro driver is doing. What is does is that it will
> > > > > > > > > > do get() in device_run(), and put() whenever the job
> > > > > > > > > > completes. This driver has been designed so when there
> > > > > > > > > > is no job, it means the firmware is currently idle and
> looking for more work.
> > > > > > > > > > So it seems like the perfect moment to
> > > > > > do suspend it.
> > > > > > > > > >
> > > > > > > > > > Nicolas
> > > > > > > > > >
> > > > > > > > > > > +
> > > > > > > > > > >  	mutex_unlock(&vpu_dev->hw_lock);
> > > > > > > > > > >
> > > > > > > > > > >  	return 0;
> > > > > > > > > > > diff --git
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5.h
> > > > > > > > > > > b/drivers/media/platform/chips-media/wave5/wave5.h
> > > > > > > > > > > index 063028eccd3b..6125eff938a8 100644
> > > > > > > > > > > ---
> > > > > > > > > > > a/drivers/media/platform/chips-media/wave5/wave5.h
> > > > > > > > > > > +++ b/drivers/media/platform/chips-media/wave5/wave5
> > > > > > > > > > > +++ .h
> > > > > > > > > > > @@ -56,6 +56,9 @@ int wave5_vpu_get_version(struct
> > > > > > > > > > > vpu_device *vpu_dev, u32 *revision);
> > > > > > > > > > >
> > > > > > > > > > >  int wave5_vpu_init(struct device *dev, u8 *fw,
> > > > > > > > > > > size_t size);
> > > > > > > > > > >
> > > > > > > > > > > +int wave5_vpu_sleep_wake(struct device *dev, bool
> > > > > > > > > > > +i_sleep_wake, const
> > > > > > > > > > uint16_t *code,
> > > > > > > > > > > +			 size_t size);
> > > > > > > > > > > +
> > > > > > > > > > >  int wave5_vpu_reset(struct device *dev, enum
> > > > > > > > > > > sw_reset_mode reset_mode);
> > > > > > > > > > >
> > > > > > > > > > >  int wave5_vpu_build_up_dec_param(struct
> > > > > > > > > > > vpu_instance *inst, struct dec_open_param *param);
> > > > > > > > >
> > > > > > >
> > > > >
> >

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