Received-SPF: pass (google.com: domain of linux-kernel+bounces-140379-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) client-ip=2604:1380:40f1:3f00::1;
Message-ID: <155bb2c2-21b9-48d5-9615-7a44d4b6a590@ideasonboard.com>
Date: Thu, 11 Apr 2024 17:18:14 +0530
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v3 9/9] media: subdev: Support single-stream case in
 v4l2_subdev_enable/disable_streams()
Content-Language: en-US
To: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
 Mauro Carvalho Chehab <mchehab@kernel.org>, Hans Verkuil
 <hverkuil@xs4all.nl>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
 Sakari Ailus <sakari.ailus@linux.intel.com>
References: <20240410-enable-streams-impro-v3-0-e5e7a5da7420@ideasonboard.com>
 <20240410-enable-streams-impro-v3-9-e5e7a5da7420@ideasonboard.com>
 <f8e293b7-6a06-4477-9c7e-d1b83163f8e1@ideasonboard.com>
 <72940e89-0384-4fd3-8a10-42d6db44fdf0@ideasonboard.com>
From: Umang Jain <umang.jain@ideasonboard.com>
In-Reply-To: <72940e89-0384-4fd3-8a10-42d6db44fdf0@ideasonboard.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

Hi Tomi,

On 11/04/24 4:37 pm, Tomi Valkeinen wrote:
> On 11/04/2024 14:02, Umang Jain wrote:
>> Hi Tomi,
>>
>> On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
>>> At the moment the v4l2_subdev_enable/disable_streams() functions call
>>> fallback helpers to handle the case where the subdev only implements
>>> .s_stream(), and the main function handles the case where the subdev
>>> implements streams (V4L2_SUBDEV_FL_STREAMS, which implies
>>> .enable/disable_streams()).
>>>
>>> What is missing is support for subdevs which do not implement streams
>>> support, but do implement .enable/disable_streams(). Example cases of
>>> these subdevices are single-stream cameras, where using
>>> .enable/disable_streams() is not required but helps us remove the users
>>> of the legacy .s_stream(), and subdevices with multiple source pads 
>>> (but
>>> single stream per pad), where .enable/disable_streams() allows the
>>> subdevice to control the enable/disable state per pad.
>>>
>>> The two single-streams cases (.s_stream() and 
>>> .enable/disable_streams())
>>> are very similar, and with small changes we can change the
>>> v4l2_subdev_enable/disable_streams() functions to support all three
>>> cases, without needing separate fallback functions.
>>>
>>> A few potentially problematic details, though:
>>
>> Does this mean the patch needs to be worked upon more ?
>
> I don't see the two issues below as blockers.
>
>> I quickly tested the series by applying it locally with my use case 
>> of IMX283 .enable/disable streams and s_stream as the helper function 
>> and it seems I am still seeing the same behaviour as before (i.e. not 
>> being streamed) and have to carry the workaround as mentioned in [1] 
>> **NOTE**
>
> Ok... Then something bugs here, as it is supposed to fix the problem. 
> Can you trace the code a bit to see where it goes wrong?
>
> The execution should go to the "if (!(sd->flags & 
> V4L2_SUBDEV_FL_STREAMS))" blocks in v4l2_subdev_collect_streams() and 
> v4l2_subdev_set_streams_enabled(),

The execution is not reaching in v4l2_subdev_collect streams() even, it 
returns at

     if (!streams_mask)
                 return 0;

in v4l2_subdev_enable_streams()

Refer to : https://paste.debian.net/1313760/

My tree is based on v6.8 currently, but the series applies cleanly, so I 
have not introduced any  rebase artifacts. If you think, v6.8 might be 
causing issues, I'll then try to test on RPi 5 with the latest media 
tree perhaps.

>
>  Tomi
>
>>
>> [1] 
>> https://lore.kernel.org/linux-media/20240313070705.91140-1-umang.jain@ideasonboard.com/
>>
>>>
>>> - For the single-streams cases we use sd->enabled_pads field, which
>>>    limits the number of pads for the subdevice to 64. For simplicity I
>>>    added the check for this limitation to the beginning of the 
>>> function,
>>>    and it also applies to the streams case.
>>>
>>> - The fallback functions only allowed the target pad to be a source 
>>> pad.
>>>    It is not very clear to me why this check was needed, but it was not
>>>    needed in the streams case. However, I doubt the
>>>    v4l2_subdev_enable/disable_streams() code has ever been tested with
>>>    sink pads, so to be on the safe side, I added the same check
>>>    to the v4l2_subdev_enable/disable_streams() functions.
>>>
>>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>>> ---
>>>   drivers/media/v4l2-core/v4l2-subdev.c | 187 
>>> ++++++++++++++--------------------
>>>   1 file changed, 79 insertions(+), 108 deletions(-)
>>>
>>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c 
>>> b/drivers/media/v4l2-core/v4l2-subdev.c
>>> index 0d376d72ecc7..4a73886741f9 100644
>>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
>>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
>>> @@ -2106,6 +2106,13 @@ static void 
>>> v4l2_subdev_collect_streams(struct v4l2_subdev *sd,
>>>                       u64 *found_streams,
>>>                       u64 *enabled_streams)
>>>   {
>>> +    if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
>>> +        *found_streams = BIT_ULL(0);
>>> +        if (sd->enabled_pads & BIT_ULL(pad))
>>> +            *enabled_streams = BIT_ULL(0);
>>> +        return;
>>> +    }
>>> +
>>>       *found_streams = 0;
>>>       *enabled_streams = 0;
>>> @@ -2127,6 +2134,14 @@ static void 
>>> v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>>>                           u32 pad, u64 streams_mask,
>>>                           bool enabled)
>>>   {
>>> +    if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
>>> +        if (enabled)
>>> +            sd->enabled_pads |= BIT_ULL(pad);
>>> +        else
>>> +            sd->enabled_pads &= ~BIT_ULL(pad);
>>> +        return;
>>> +    }
>>> +
>>>       for (unsigned int i = 0; i < 
>>> state->stream_configs.num_configs; ++i) {
>>>           struct v4l2_subdev_stream_config *cfg =
>>>               &state->stream_configs.configs[i];
>>> @@ -2136,51 +2151,6 @@ static void 
>>> v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>>>       }
>>>   }
>>> -static int v4l2_subdev_enable_streams_fallback(struct v4l2_subdev 
>>> *sd, u32 pad,
>>> -                           u64 streams_mask)
>>> -{
>>> -    struct device *dev = sd->entity.graph_obj.mdev->dev;
>>> -    int ret;
>>> -
>>> -    /*
>>> -     * The subdev doesn't implement pad-based stream enable, fall back
>>> -     * to the .s_stream() operation.
>>> -     */
>>> -    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>> -        return -EOPNOTSUPP;
>>> -
>>> -    /*
>>> -     * .s_stream() means there is no streams support, so only 
>>> allowed stream
>>> -     * is the implicit stream 0.
>>> -     */
>>> -    if (streams_mask != BIT_ULL(0))
>>> -        return -EOPNOTSUPP;
>>> -
>>> -    /*
>>> -     * We use a 64-bit bitmask for tracking enabled pads, so only 
>>> subdevices
>>> -     * with 64 pads or less can be supported.
>>> -     */
>>> -    if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>>> -        return -EOPNOTSUPP;
>>> -
>>> -    if (sd->enabled_pads & BIT_ULL(pad)) {
>>> -        dev_dbg(dev, "pad %u already enabled on %s\n",
>>> -            pad, sd->entity.name);
>>> -        return -EALREADY;
>>> -    }
>>> -
>>> -    /* Start streaming when the first pad is enabled. */
>>> -    if (!sd->enabled_pads) {
>>> -        ret = v4l2_subdev_call(sd, video, s_stream, 1);
>>> -        if (ret)
>>> -            return ret;
>>> -    }
>>> -
>>> -    sd->enabled_pads |= BIT_ULL(pad);
>>> -
>>> -    return 0;
>>> -}
>>> -
>>>   int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
>>>                      u64 streams_mask)
>>>   {
>>> @@ -2189,21 +2159,33 @@ int v4l2_subdev_enable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       bool already_streaming;
>>>       u64 enabled_streams;
>>>       u64 found_streams;
>>> +    bool use_s_stream;
>>>       int ret;
>>>       /* A few basic sanity checks first. */
>>>       if (pad >= sd->entity.num_pads)
>>>           return -EINVAL;
>>> +    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>> +        return -EOPNOTSUPP;
>>> +
>>> +    /*
>>> +     * We use a 64-bit bitmask for tracking enabled pads, so only 
>>> subdevices
>>> +     * with 64 pads or less can be supported.
>>> +     */
>>> +    if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>>> +        return -EOPNOTSUPP;
>>> +
>>>       if (!streams_mask)
>>>           return 0;
>>>       /* Fallback on .s_stream() if .enable_streams() isn't 
>>> available. */
>>> -    if (!v4l2_subdev_has_op(sd, pad, enable_streams))
>>> -        return v4l2_subdev_enable_streams_fallback(sd, pad,
>>> -                               streams_mask);
>>> +    use_s_stream = !v4l2_subdev_has_op(sd, pad, enable_streams);
>>> -    state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    if (!use_s_stream)
>>> +        state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    else
>>> +        state = NULL;
>>>       /*
>>>        * Verify that the requested streams exist and that they are not
>>> @@ -2231,9 +2213,18 @@ int v4l2_subdev_enable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       already_streaming = v4l2_subdev_is_streaming(sd);
>>> -    /* Call the .enable_streams() operation. */
>>> -    ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
>>> -                   streams_mask);
>>> +    if (!use_s_stream) {
>>> +        /* Call the .enable_streams() operation. */
>>> +        ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
>>> +                       streams_mask);
>>> +    } else {
>>> +        /* Start streaming when the first pad is enabled. */
>>> +        if (!already_streaming)
>>> +            ret = v4l2_subdev_call(sd, video, s_stream, 1);
>>> +        else
>>> +            ret = 0;
>>> +    }
>>> +
>>>       if (ret) {
>>>           dev_dbg(dev, "enable streams %u:%#llx failed: %d\n", pad,
>>>               streams_mask, ret);
>>> @@ -2243,34 +2234,32 @@ int v4l2_subdev_enable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       /* Mark the streams as enabled. */
>>>       v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, 
>>> true);
>>> -    if (!already_streaming)
>>> +    if (!use_s_stream && !already_streaming)
>>>           v4l2_subdev_enable_privacy_led(sd);
>>>   done:
>>> -    v4l2_subdev_unlock_state(state);
>>> +    if (!use_s_stream)
>>> +        v4l2_subdev_unlock_state(state);
>>>       return ret;
>>>   }
>>>   EXPORT_SYMBOL_GPL(v4l2_subdev_enable_streams);
>>> -static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev 
>>> *sd, u32 pad,
>>> -                        u64 streams_mask)
>>> +int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>>> +                u64 streams_mask)
>>>   {
>>>       struct device *dev = sd->entity.graph_obj.mdev->dev;
>>> +    struct v4l2_subdev_state *state;
>>> +    u64 enabled_streams;
>>> +    u64 found_streams;
>>> +    bool use_s_stream;
>>>       int ret;
>>> -    /*
>>> -     * If the subdev doesn't implement pad-based stream enable, 
>>> fall back
>>> -     * to the .s_stream() operation.
>>> -     */
>>> -    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>> -        return -EOPNOTSUPP;
>>> +    /* A few basic sanity checks first. */
>>> +    if (pad >= sd->entity.num_pads)
>>> +        return -EINVAL;
>>> -    /*
>>> -     * .s_stream() means there is no streams support, so only 
>>> allowed stream
>>> -     * is the implicit stream 0.
>>> -     */
>>> -    if (streams_mask != BIT_ULL(0))
>>> +    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>>           return -EOPNOTSUPP;
>>>       /*
>>> @@ -2280,46 +2269,16 @@ static int 
>>> v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
>>>       if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>>>           return -EOPNOTSUPP;
>>> -    if (!(sd->enabled_pads & BIT_ULL(pad))) {
>>> -        dev_dbg(dev, "pad %u already disabled on %s\n",
>>> -            pad, sd->entity.name);
>>> -        return -EALREADY;
>>> -    }
>>> -
>>> -    /* Stop streaming when the last streams are disabled. */
>>> -    if (!(sd->enabled_pads & ~BIT_ULL(pad))) {
>>> -        ret = v4l2_subdev_call(sd, video, s_stream, 0);
>>> -        if (ret)
>>> -            return ret;
>>> -    }
>>> -
>>> -    sd->enabled_pads &= ~BIT_ULL(pad);
>>> -
>>> -    return 0;
>>> -}
>>> -
>>> -int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>>> -                u64 streams_mask)
>>> -{
>>> -    struct device *dev = sd->entity.graph_obj.mdev->dev;
>>> -    struct v4l2_subdev_state *state;
>>> -    u64 enabled_streams;
>>> -    u64 found_streams;
>>> -    int ret;
>>> -
>>> -    /* A few basic sanity checks first. */
>>> -    if (pad >= sd->entity.num_pads)
>>> -        return -EINVAL;
>>> -
>>>       if (!streams_mask)
>>>           return 0;
>>>       /* Fallback on .s_stream() if .disable_streams() isn't 
>>> available. */
>>> -    if (!v4l2_subdev_has_op(sd, pad, disable_streams))
>>> -        return v4l2_subdev_disable_streams_fallback(sd, pad,
>>> -                                streams_mask);
>>> +    use_s_stream = !v4l2_subdev_has_op(sd, pad, disable_streams);
>>> -    state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    if (!use_s_stream)
>>> +        state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    else
>>> +        state = NULL;
>>>       /*
>>>        * Verify that the requested streams exist and that they are not
>>> @@ -2345,9 +2304,19 @@ int v4l2_subdev_disable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask);
>>> -    /* Call the .disable_streams() operation. */
>>> -    ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
>>> -                   streams_mask);
>>> +    if (!use_s_stream) {
>>> +        /* Call the .disable_streams() operation. */
>>> +        ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
>>> +                       streams_mask);
>>> +    } else {
>>> +        /* Stop streaming when the last streams are disabled. */
>>> +
>>> +        if (!(sd->enabled_pads & ~BIT_ULL(pad)))
>>> +            ret = v4l2_subdev_call(sd, video, s_stream, 0);
>>> +        else
>>> +            ret = 0;
>>> +    }
>>> +
>>>       if (ret) {
>>>           dev_dbg(dev, "disable streams %u:%#llx failed: %d\n", pad,
>>>               streams_mask, ret);
>>> @@ -2357,10 +2326,12 @@ int v4l2_subdev_disable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, 
>>> false);
>>>   done:
>>> -    if (!v4l2_subdev_is_streaming(sd))
>>> -        v4l2_subdev_disable_privacy_led(sd);
>>> +    if (!use_s_stream) {
>>> +        if (!v4l2_subdev_is_streaming(sd))
>>> +            v4l2_subdev_disable_privacy_led(sd);
>>> -    v4l2_subdev_unlock_state(state);
>>> +        v4l2_subdev_unlock_state(state);
>>> +    }
>>>       return ret;
>>>   }
>>>
>>
>