Messages in this thread | | | Subject | Re: [RFC PATCH v1 3/5] media: tegra-video: Move PM runtime handle to streaming | From | Sowjanya Komatineni <> | Date | Tue, 28 Apr 2020 08:22:02 -0700 |
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On 4/28/20 8:15 AM, Dmitry Osipenko wrote: > External email: Use caution opening links or attachments > > > 28.04.2020 18:08, Sowjanya Komatineni пишет: >> On 4/28/20 7:59 AM, Dmitry Osipenko wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> 28.04.2020 17:51, Sowjanya Komatineni пишет: >>>> On 4/28/20 6:59 AM, Dmitry Osipenko wrote: >>>>> External email: Use caution opening links or attachments >>>>> >>>>> >>>>> 28.04.2020 07:20, Sowjanya Komatineni пишет: >>>>>> diff --git a/drivers/staging/media/tegra-video/csi.c >>>>>> b/drivers/staging/media/tegra-video/csi.c >>>>>> index b3dd0c3..29ccdae 100644 >>>>>> --- a/drivers/staging/media/tegra-video/csi.c >>>>>> +++ b/drivers/staging/media/tegra-video/csi.c >>>>>> @@ -272,8 +272,25 @@ static int tegra_csi_s_stream(struct v4l2_subdev >>>>>> *subdev, int enable) >>>>>> struct tegra_vi_channel *chan = >>>>>> v4l2_get_subdev_hostdata(subdev); >>>>>> struct tegra_csi_channel *csi_chan = to_csi_chan(subdev); >>>>>> struct tegra_csi *csi = csi_chan->csi; >>>>>> + int ret; >>>>>> + >>>>>> + if (enable && atomic_add_return(1, &csi->clk_refcnt) == 1) { >>>>>> + ret = pm_runtime_get_sync(csi->dev); >>>>>> + if (ret < 0) { >>>>>> + dev_err(csi->dev, >>>>>> + "failed to get runtime PM: %d\n", ret); >>>>>> + pm_runtime_put_noidle(csi->dev); > Why this pm_runtime_put_noidle() is needed? This should be wrong, please > remove it.
pm_runtime_get_sync() increments power.usage_count prior to rpm_resume
if rpm_resume fails it does not decrement usage_count.
So to balance count on failure, calling pm_runtime_put_noidle()
> >>>>>> + atomic_dec(&csi->clk_refcnt); >>>>>> + return ret; >>>>>> + } >>>>>> + } >>>>>> + >>>>>> + ret = csi->ops->csi_streaming(csi_chan, chan->pg_mode, enable); >>>>>> >>>>>> - return csi->ops->csi_streaming(csi_chan, chan->pg_mode, enable); >>>>>> + if ((ret < 0 || !enable) && >>>>>> atomic_dec_and_test(&csi->clk_refcnt)) >>>>>> + pm_runtime_put_sync(csi->dev); >>>>> Runtime PM maintains its own refcount, why these >>>>> clk_refcnt/power_on_refcnt are needed? >>>> Streaming is per channel and we can't turn power/clocks off while other >>>> channels may still be running. >>>> >>> All channels use the same CSI device. You should remove the custom >>> refcounting. >>> >>> BTW, next time you'll really need to do refcounting, use the generic >>> kref. >> Before channel stream we enable power/clocks and after streaming we stop. >> >> So without refcount, on stream stop of any of the channel RPM put turns >> power/clock but other channels will still be streaming. >> > Runtime PM uses its own refcounting. Please consult the RPM code and > documentation. > > https://elixir.bootlin.com/linux/v5.7-rc3/source/include/linux/pm_runtime.h#L78 > https://elixir.bootlin.com/linux/v5.7-rc3/source/drivers/base/power/runtime.c#L1079 Got it. Will remove refcount for RPM put/get
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