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Date:   Tue, 5 May 2020 09:53:08 -0300
From:   Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Maxime Ripard <mripard@...nel.org>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-media <linux-media@...r.kernel.org>,
        linux-sunxi@...glegroups.com,
        Jernej Škrabec <jernej.skrabec@...il.com>
Subject: Re: [linux-sunxi] [PATCH v2 2/2] media: cedrus: Implement runtime PM

On Wed, 22 Apr 2020 at 01:00, Samuel Holland <samuel@...lland.org> wrote:
>
> This allows the VE clocks and PLL_VE to be disabled most of the time.
> A runtime PM reference is held while streaming.
>
> Originally-by: Jernej Škrabec <jernej.skrabec@...il.com>

Originally-by is not documented, perhaps just go with Signed-off-by,
as Jernej suggested.

> Signed-off-by: Samuel Holland <samuel@...lland.org>
> ---
>
> v2: moved PM reference to cedrus_{start,stop}_streaming, based on an
>     earlier patch by Jernej Skrabec. Removes the need for autosuspend.
>     I tested this with running 2x v4l2-request-test in parallel.
>
> ---
>  drivers/staging/media/sunxi/cedrus/cedrus.c   |   7 ++
>  .../staging/media/sunxi/cedrus/cedrus_hw.c    | 106 ++++++++++++------
>  .../staging/media/sunxi/cedrus/cedrus_hw.h    |   3 +
>  .../staging/media/sunxi/cedrus/cedrus_video.c |  33 ++++--
>  4 files changed, 104 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.c b/drivers/staging/media/sunxi/cedrus/cedrus.c
> index 05a85517ff60..bc27f9430eeb 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus.c
> @@ -16,6 +16,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/pm.h>
>
>  #include <media/v4l2-device.h>
>  #include <media/v4l2-ioctl.h>
> @@ -551,12 +552,18 @@ static const struct of_device_id cedrus_dt_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, cedrus_dt_match);
>
> +static const struct dev_pm_ops cedrus_dev_pm_ops = {
> +       SET_RUNTIME_PM_OPS(cedrus_hw_suspend,
> +                          cedrus_hw_resume, NULL)
> +};
> +
>  static struct platform_driver cedrus_driver = {
>         .probe          = cedrus_probe,
>         .remove         = cedrus_remove,
>         .driver         = {
>                 .name           = CEDRUS_NAME,
>                 .of_match_table = of_match_ptr(cedrus_dt_match),
> +               .pm             = &cedrus_dev_pm_ops,
>         },
>  };
>  module_platform_driver(cedrus_driver);
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
> index daf5f244f93b..1744e6fcc999 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
> @@ -19,6 +19,7 @@
>  #include <linux/dma-mapping.h>
>  #include <linux/interrupt.h>
>  #include <linux/clk.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/regmap.h>
>  #include <linux/reset.h>
>  #include <linux/soc/sunxi/sunxi_sram.h>
> @@ -140,6 +141,64 @@ static irqreturn_t cedrus_irq(int irq, void *data)
>         return IRQ_HANDLED;
>  }
>
> +int cedrus_hw_suspend(struct device *device)
> +{
> +       struct cedrus_dev *dev = dev_get_drvdata(device);
> +
> +       reset_control_assert(dev->rstc);
> +
> +       clk_disable_unprepare(dev->ram_clk);
> +       clk_disable_unprepare(dev->mod_clk);
> +       clk_disable_unprepare(dev->ahb_clk);
> +

You can use clk_bulk API here.

> +       return 0;
> +}
> +
> +int cedrus_hw_resume(struct device *device)
> +{
> +       struct cedrus_dev *dev = dev_get_drvdata(device);
> +       int ret;
> +
> +       ret = clk_prepare_enable(dev->ahb_clk);
> +       if (ret) {
> +               dev_err(dev->dev, "Failed to enable AHB clock\n");
> +
> +               return ret;
> +       }
> +
> +       ret = clk_prepare_enable(dev->mod_clk);
> +       if (ret) {
> +               dev_err(dev->dev, "Failed to enable MOD clock\n");
> +
> +               goto err_ahb_clk;
> +       }
> +
> +       ret = clk_prepare_enable(dev->ram_clk);
> +       if (ret) {
> +               dev_err(dev->dev, "Failed to enable RAM clock\n");
> +
> +               goto err_mod_clk;
> +       }
> +
> +       ret = reset_control_reset(dev->rstc);
> +       if (ret) {
> +               dev_err(dev->dev, "Failed to apply reset\n");
> +
> +               goto err_ram_clk;
> +       }
> +
> +       return 0;
> +
> +err_ram_clk:
> +       clk_disable_unprepare(dev->ram_clk);
> +err_mod_clk:
> +       clk_disable_unprepare(dev->mod_clk);
> +err_ahb_clk:
> +       clk_disable_unprepare(dev->ahb_clk);
> +
> +       return ret;
> +}
> +
>  int cedrus_hw_probe(struct cedrus_dev *dev)
>  {
>         const struct cedrus_variant *variant;
> @@ -236,42 +295,17 @@ int cedrus_hw_probe(struct cedrus_dev *dev)
>                 goto err_sram;
>         }
>
> -       ret = clk_prepare_enable(dev->ahb_clk);
> -       if (ret) {
> -               dev_err(dev->dev, "Failed to enable AHB clock\n");
> -
> -               goto err_sram;
> -       }
> -
> -       ret = clk_prepare_enable(dev->mod_clk);
> -       if (ret) {
> -               dev_err(dev->dev, "Failed to enable MOD clock\n");
> -
> -               goto err_ahb_clk;
> -       }
> -
> -       ret = clk_prepare_enable(dev->ram_clk);
> -       if (ret) {
> -               dev_err(dev->dev, "Failed to enable RAM clock\n");
> -
> -               goto err_mod_clk;
> -       }
> -
> -       ret = reset_control_reset(dev->rstc);
> -       if (ret) {
> -               dev_err(dev->dev, "Failed to apply reset\n");
> -
> -               goto err_ram_clk;
> +       pm_runtime_enable(dev->dev);
> +       if (!pm_runtime_enabled(dev->dev)) {
> +               ret = cedrus_hw_resume(dev->dev);
> +               if (ret)
> +                       goto err_pm;
>         }
>
>         return 0;
>
> -err_ram_clk:
> -       clk_disable_unprepare(dev->ram_clk);
> -err_mod_clk:
> -       clk_disable_unprepare(dev->mod_clk);
> -err_ahb_clk:
> -       clk_disable_unprepare(dev->ahb_clk);
> +err_pm:
> +       pm_runtime_disable(dev->dev);
>  err_sram:
>         sunxi_sram_release(dev->dev);
>  err_mem:
> @@ -282,11 +316,9 @@ int cedrus_hw_probe(struct cedrus_dev *dev)
>
>  void cedrus_hw_remove(struct cedrus_dev *dev)
>  {
> -       reset_control_assert(dev->rstc);
> -
> -       clk_disable_unprepare(dev->ram_clk);
> -       clk_disable_unprepare(dev->mod_clk);
> -       clk_disable_unprepare(dev->ahb_clk);
> +       pm_runtime_disable(dev->dev);
> +       if (!pm_runtime_status_suspended(dev->dev))
> +               cedrus_hw_suspend(dev->dev);
>
>         sunxi_sram_release(dev->dev);
>
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_hw.h b/drivers/staging/media/sunxi/cedrus/cedrus_hw.h
> index 604ff932fbf5..45f641f0bfa2 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_hw.h
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_hw.h
> @@ -22,6 +22,9 @@ void cedrus_engine_disable(struct cedrus_dev *dev);
>  void cedrus_dst_format_set(struct cedrus_dev *dev,
>                            struct v4l2_pix_format *fmt);
>
> +int cedrus_hw_suspend(struct device *device);
> +int cedrus_hw_resume(struct device *device);
> +
>  int cedrus_hw_probe(struct cedrus_dev *dev);
>  void cedrus_hw_remove(struct cedrus_dev *dev);
>
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_video.c b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> index ed3f511f066f..16d82309e7b6 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_video.c
> @@ -13,6 +13,8 @@
>   * Marek Szyprowski, <m.szyprowski@...sung.com>
>   */
>
> +#include <linux/pm_runtime.h>
> +
>  #include <media/videobuf2-dma-contig.h>
>  #include <media/v4l2-device.h>
>  #include <media/v4l2-ioctl.h>
> @@ -450,12 +452,24 @@ static int cedrus_start_streaming(struct vb2_queue *vq, unsigned int count)
>                 return -EINVAL;
>         }
>
> -       if (V4L2_TYPE_IS_OUTPUT(vq->type) &&
> -           dev->dec_ops[ctx->current_codec]->start)
> -               ret = dev->dec_ops[ctx->current_codec]->start(ctx);
> +       if (V4L2_TYPE_IS_OUTPUT(vq->type)) {
> +               ret = pm_runtime_get_sync(dev->dev);

It's entirely up to you, but you could do get_sync/put
between .device_run, as everything should happen
in the context of v4l2_m2m_ops.device_run.
(In that case, I believe you'd want to enable autosuspend.)

Not sure there's much to gain from an power consumption
pov, though.

With the Originally-by changed:

Reviewed-by: Ezequiel Garcia <ezequiel@...labora.com>

Thanks,
Ezequiel

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