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    SubjectRe: [PATCH v3 4/9] media: subdev: Fix use of sd->enabled_streams in call_s_stream()
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    Hi Tomi,

    Thank you for the patch

    On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
    > call_s_stream() uses sd->enabled_streams to track whether streaming has
    > already been enabled. However,
    > v4l2_subdev_enable/disable_streams_fallback(), which was the original
    > user of this field, already uses it, and
    > v4l2_subdev_enable/disable_streams_fallback() will call call_s_stream().
    >
    > This leads to a conflict as both functions set the field. Afaics, both
    > functions set the field to the same value, so it won't cause a runtime
    > bug, but it's still wrong and if we, e.g., change how
    > v4l2_subdev_enable/disable_streams_fallback() operates we might easily
    > cause bugs.
    >
    > Fix this by adding a new field, 'streaming_enabled', for
    > call_s_stream().

    Just a suggestion, as this is only used in call_s_stream(), maybe naming
    this field 's_stream_enabled' ?

    Rest looks good to me,

    Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

    >
    > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
    > ---
    > drivers/media/v4l2-core/v4l2-subdev.c | 8 ++------
    > include/media/v4l2-subdev.h | 3 +++
    > 2 files changed, 5 insertions(+), 6 deletions(-)
    >
    > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
    > index 606a909cd778..6cd353d83dfc 100644
    > --- a/drivers/media/v4l2-core/v4l2-subdev.c
    > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
    > @@ -421,12 +421,8 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable)
    > * The .s_stream() operation must never be called to start or stop an
    > * already started or stopped subdev. Catch offenders but don't return
    > * an error yet to avoid regressions.
    > - *
    > - * As .s_stream() is mutually exclusive with the .enable_streams() and
    > - * .disable_streams() operation, we can use the enabled_streams field
    > - * to store the subdev streaming state.
    > */
    > - if (WARN_ON(!!sd->enabled_streams == !!enable))
    > + if (WARN_ON(sd->streaming_enabled == !!enable))
    > return 0;
    >
    > ret = sd->ops->video->s_stream(sd, enable);
    > @@ -437,7 +433,7 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable)
    > }
    >
    > if (!ret) {
    > - sd->enabled_streams = enable ? BIT(0) : 0;
    > + sd->streaming_enabled = enable;
    >
    > if (enable)
    > v4l2_subdev_enable_privacy_led(sd);
    > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
    > index a9e6b8146279..f55d03e0acc1 100644
    > --- a/include/media/v4l2-subdev.h
    > +++ b/include/media/v4l2-subdev.h
    > @@ -1043,6 +1043,8 @@ struct v4l2_subdev_platform_data {
    > * v4l2_subdev_enable_streams() and
    > * v4l2_subdev_disable_streams() helper functions for fallback
    > * cases.
    > + * @streaming_enabled: Tracks whether streaming has been enabled with s_stream.
    > + * This is only for call_s_stream() internal use.
    > *
    > * Each instance of a subdev driver should create this struct, either
    > * stand-alone or embedded in a larger struct.
    > @@ -1091,6 +1093,7 @@ struct v4l2_subdev {
    > */
    > struct v4l2_subdev_state *active_state;
    > u64 enabled_streams;
    > + bool streaming_enabled;
    > };
    >
    >
    >


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