[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <e9f0ed24-6e24-4575-8028-b62eac1f37c6@ideasonboard.com>
Date: Thu, 11 Apr 2024 09:19:02 +0300
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Umang Jain <umang.jain@...asonboard.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
Mauro Carvalho Chehab <mchehab@...nel.org>, Hans Verkuil
<hverkuil@...all.nl>, Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Sakari Ailus <sakari.ailus@...ux.intel.com>
Subject: Re: [PATCH v3 4/9] media: subdev: Fix use of sd->enabled_streams in
call_s_stream()
On 11/04/2024 08:16, Umang Jain wrote:
> 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' ?
Yes, I think that's a good idea.
Tomi
> Rest looks good to me,
>
> Reviewed-by: Umang Jain <umang.jain@...asonboard.com>
>
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.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;
>> };
>>
>
Powered by blists - more mailing lists