Re: [linux-sunxi] [PATCH v2 2/2] media: cedrus: Implement runtime PM

From: Samuel Holland
Date: Sat May 09 2020 - 16:12:24 EST

On 5/5/20 7:53 AM, Ezequiel Garcia wrote:
> On Wed, 22 Apr 2020 at 01:00, Samuel Holland <samuel@xxxxxxxxxxxx> 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 Åkrabec <jernej.skrabec@xxxxxxxxx>
>
> Originally-by is not documented, perhaps just go with Signed-off-by,
> as Jernej suggested.
>
>> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx>
>> ---
>>
>> 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.

Since this change is already tested, I'd prefer to do that as a separate patch.

>> + 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@xxxxxxxxxxx>
>> */
>>
>> +#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.

Agreed. Either you have a short autosuspend delay, and get per-frame latency; or
a longer delay, and the hardware is on for the entire stream anyway. So I don't
think it's worth the overhead.

> With the Originally-by changed:
>
> Reviewed-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
>
> Thanks,
> Ezequiel
>

Thanks,
Samuel