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Message-ID: <CAD=FV=VxzEV40g+ieuEN+7o=34+wM8MHO8o7T5zA1Yosx7SVWg@mail.gmail.com>
Date: Tue, 17 Mar 2020 14:38:39 -0700
From: Doug Anderson <dianders@...omium.org>
To: Kalyan Thota <kalyan_t@...eaurora.org>
Cc: dri-devel <dri-devel@...ts.freedesktop.org>,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
freedreno <freedreno@...ts.freedesktop.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
Rob Clark <robdclark@...il.com>,
Sean Paul <seanpaul@...omium.org>,
"Kristian H. Kristensen" <hoegsberg@...omium.org>,
Jeykumar Sankaran <jsanka@...eaurora.org>,
travitej@...eaurora.org, Stephen Boyd <swboyd@...omium.org>
Subject: Re: [PATCH] drm/msm/dpu: ensure device suspend happens during PM sleep
Hi,
On Mon, Mar 16, 2020 at 4:06 AM Kalyan Thota <kalyan_t@...eaurora.org> wrote:
>
> "The PM core always increments the runtime usage counter
> before calling the ->suspend() callback and decrements it
> after calling the ->resume() callback"
>
> DPU and DSI are managed as runtime devices. When
> suspend is triggered, PM core adds a refcount on all the
> devices and calls device suspend, since usage count is
> already incremented, runtime suspend was not getting called
> and it kept the clocks on which resulted in target not
> entering into XO shutdown.
>
> Add changes to manage runtime devices during pm sleep.
>
> Signed-off-by: Kalyan Thota <kalyan_t@...eaurora.org>
> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 41 +++++++++++++++++++++++++++++++++
> drivers/gpu/drm/msm/dsi/dsi.c | 7 ++++++
> drivers/gpu/drm/msm/msm_drv.c | 14 +++++++++++
> drivers/gpu/drm/msm/msm_kms.h | 2 ++
> 4 files changed, 64 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index cb08faf..6e103d5 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -26,6 +26,7 @@
> #include "dpu_encoder.h"
> #include "dpu_plane.h"
> #include "dpu_crtc.h"
> +#include "dsi.h"
>
> #define CREATE_TRACE_POINTS
> #include "dpu_trace.h"
> @@ -250,6 +251,37 @@ static void dpu_kms_disable_commit(struct msm_kms *kms)
> pm_runtime_put_sync(&dpu_kms->pdev->dev);
> }
>
> +static void _dpu_kms_disable_dpu(struct msm_kms *kms)
> +{
> + struct drm_device *dev;
> + struct msm_drm_private *priv;
> + struct dpu_kms *dpu_kms;
> + int i = 0;
> + struct msm_dsi *dsi;
> +
> + dpu_kms = to_dpu_kms(kms);
> + dev = dpu_kms->dev;
> + if (!dev) {
> + DPU_ERROR("invalid device\n");
> + return;
> + }
> +
> + priv = dev->dev_private;
> + if (!priv) {
> + DPU_ERROR("invalid private data\n");
> + return;
> + }
> +
> + dpu_kms_disable_commit(kms);
> +
> + for (i = 0; i < ARRAY_SIZE(priv->dsi); i++) {
> + if (!priv->dsi[i])
> + continue;
> + dsi = priv->dsi[i];
> + pm_runtime_put_sync(&dsi->pdev->dev);
> + }
> +}
> +
> static ktime_t dpu_kms_vsync_time(struct msm_kms *kms, struct drm_crtc *crtc)
> {
> struct drm_encoder *encoder;
> @@ -683,6 +715,7 @@ static void dpu_irq_uninstall(struct msm_kms *kms)
> #ifdef CONFIG_DEBUG_FS
> .debugfs_init = dpu_kms_debugfs_init,
> #endif
> + .disable_dpu = _dpu_kms_disable_dpu,
> };
>
> static void _dpu_kms_mmu_destroy(struct dpu_kms *dpu_kms)
> @@ -1053,7 +1086,15 @@ static int __maybe_unused dpu_runtime_resume(struct device *dev)
> return rc;
> }
>
> +
> +static int __maybe_unused dpu_pm_suspend_late(struct device *dev)
> +{
> + pm_runtime_get_noresume(dev);
> + return 0;
> +}
> +
> static const struct dev_pm_ops dpu_pm_ops = {
> + SET_LATE_SYSTEM_SLEEP_PM_OPS(dpu_pm_suspend_late, NULL)
> SET_RUNTIME_PM_OPS(dpu_runtime_suspend, dpu_runtime_resume, NULL)
> };
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi.c b/drivers/gpu/drm/msm/dsi/dsi.c
> index 55ea4bc2..3d3740e 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi.c
> @@ -154,12 +154,19 @@ static int dsi_dev_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static int __maybe_unused dsi_pm_suspend_late(struct device *dev)
> +{
> + pm_runtime_get_noresume(dev);
> + return 0;
> +}
> +
> static const struct of_device_id dt_match[] = {
> { .compatible = "qcom,mdss-dsi-ctrl" },
> {}
> };
>
> static const struct dev_pm_ops dsi_pm_ops = {
> + SET_LATE_SYSTEM_SLEEP_PM_OPS(dsi_pm_suspend_late, NULL)
> SET_RUNTIME_PM_OPS(msm_dsi_runtime_suspend, msm_dsi_runtime_resume, NULL)
> };
>
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index e4b750b..12ec1c6 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -1038,6 +1038,7 @@ static int msm_pm_suspend(struct device *dev)
> {
> struct drm_device *ddev = dev_get_drvdata(dev);
> struct msm_drm_private *priv = ddev->dev_private;
> + struct msm_kms *kms = priv->kms;
>
> if (WARN_ON(priv->pm_state))
> drm_atomic_state_put(priv->pm_state);
> @@ -1049,6 +1050,11 @@ static int msm_pm_suspend(struct device *dev)
> return ret;
> }
>
> + if (kms->funcs->disable_dpu)
> + kms->funcs->disable_dpu(kms);
> +
> + pm_runtime_put_sync(dev);
> +
> return 0;
> }
>
> @@ -1067,6 +1073,13 @@ static int msm_pm_resume(struct device *dev)
>
> return ret;
> }
> +
> +static int msm_pm_suspend_late(struct device *dev)
> +{
> + pm_runtime_get_noresume(dev);
> + return 0;
> +}
> +
> #endif
>
> #ifdef CONFIG_PM
> @@ -1100,6 +1113,7 @@ static int msm_runtime_resume(struct device *dev)
> #endif
>
> static const struct dev_pm_ops msm_pm_ops = {
> + SET_LATE_SYSTEM_SLEEP_PM_OPS(msm_pm_suspend_late, NULL)
> SET_SYSTEM_SLEEP_PM_OPS(msm_pm_suspend, msm_pm_resume)
> SET_RUNTIME_PM_OPS(msm_runtime_suspend, msm_runtime_resume, NULL)
> };
> diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h
> index 1cbef6b..c73a89b 100644
> --- a/drivers/gpu/drm/msm/msm_kms.h
> +++ b/drivers/gpu/drm/msm/msm_kms.h
> @@ -126,6 +126,8 @@ struct msm_kms_funcs {
> /* debugfs: */
> int (*debugfs_init)(struct msm_kms *kms, struct drm_minor *minor);
> #endif
> + void (*disable_dpu)(struct msm_kms *kms);
> +
I'm by no means an expert on any of this, but it seems awfully
asymmetric to me and that feels like you're going to end up with bugs.
* Is it possible that disable_dpu() will be called more than once
during normal operation, like if the screen goes off? Will your
counts be off then?
* What happens if suspend is aborted partway through (by getting a
wakeup even as you're suspending, for instance)? In such a case some
of the normal suspend calls will be called but "suspend_late" won't be
called. Does that mess up your counting?
>From your description, it sure seems like this part of the
runtime_pm.rst doc is relevant to you:
> Namely, if a system suspend .prepare() callback returns a positive
> number for a device, that indicates to the PM core that the device
> appears to be runtime-suspended and its state is fine, so it may
> be left in runtime suspend provided that all of its descendants
> are also left in runtime suspend.
Did I misunderstand and this isn't what you want? Looking a bit
further, maybe the right thing is to use the "SMART_SUSPEND" flag?
I'll also note that sometimes when people just want to be Runtime PM
managed that I see this pattern:
SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)
-Doug
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