by Tomi Valkeinen

[permalink] [raw]

Subject: Re: [PATCH v5 09/10] media: subdev: Support single-stream case in v4l2_subdev_enable/disable_streams()

On 24/04/2024 16:09, Laurent Pinchart wrote:
> On Wed, Apr 24, 2024 at 04:05:31PM +0300, Tomi Valkeinen wrote:
>> On 19/04/2024 18:36, Laurent Pinchart wrote:
>>> On Tue, Apr 16, 2024 at 04:55:12PM +0300, 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:
>>>>
>>>> - 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.
>>>>
>>>
>>> Now that v4l2_subdev_enable_streams() is usable by (almost) every
>>> driver, should we update documentation to indicate that manual calls to
>>> .s_stream() should be avoided ?
>>
>> How about:
>>
>> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
>> index dabe1b5dfe4a..f52bb790773c 100644
>> --- a/include/media/v4l2-subdev.h
>> +++ b/include/media/v4l2-subdev.h
>> @@ -450,6 +450,11 @@ enum v4l2_subdev_pre_streamon_flags {
>> * already started or stopped subdev. Also see call_s_stream wrapper in
>> * v4l2-subdev.c.
>> *
>> + * New drivers should instead implement &v4l2_subdev_pad_ops.enable_streams
>> + * and &v4l2_subdev_pad_ops.disable_streams operations, and use
>> + * v4l2_subdev_s_stream_helper for the &v4l2_subdev_video_ops.s_stream
>> + * operation to support legacy users.A
>> + *
>
> Add
>
> * Drivers should also not call the .s_stream() subdev operation directly,
> * but use the v4l2_subdev_enable_streams() and
> * v4l2_subdev_disable_streams() helpers.
>
>> * @g_pixelaspect: callback to return the pixelaspect ratio.
>> *
>> * @s_dv_timings: Set custom dv timings in the sub device. This is used
>>
>>
>> Although now that I think about it, can we "ever" get rid of s_stream?
>> enable_streams is only usable if the subdev has pads.
>
> Do we have pad-less subdevs that can stream ?

Probably not, but isn't s_stream used to enable any type of subdev? Or
is there a different op to power on padless subdevs?

Tomi

>
>> If that's the
>> case, the text above should probably clarify when one should continue
>> using s_stream.
>>
>>>> Signed-off-by: Tomi Valkeinen <[email protected]>
>>>> ---
>>>> 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 e45fd42da1e3..10406acfb9d0 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);
>>>> + *enabled_streams =
>>>> + (sd->enabled_pads & BIT_ULL(pad)) ? BIT_ULL(0) : 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 the 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);
>>>
>>> state gets set to a non-null value above if the subdev has an
>>> enable_streams operation, while in v4l2_subdev_set_streams_enabled(),
>>
>> That's not quite true, v4l2_subdev_lock_and_get_active_state() returns
>> NULL if there's no state. If the driver has .enable_streams but no
>> subdev-state, we'll have NULL state. But is that a driver bug? Probably,
>> although I'm not quite sure. Whereas V4L2_SUBDEV_FL_STREAMS without
>> state is a driver bug.
>>
>>> you use it if the V4L2_SUBDEV_FL_STREAMS flag is set. The second
>>> condition is a subset of the first one, so it should be safe now, but I
>>> wonder if we're at risk of crashes in the future when reworking the
>>> code. I'm probably worrying needlessly.
>>
>> I agree that this is a bit messy. We have multiple different scenarios
>> which we handle in the same functions, and it's somewhat unclear what
>> op/state/flag combinations the drivers are allowed to have and what not.
>>
>> I could add a !state check here, and then use sd->enabled_pads. But that
>> doesn't feel correct, and I think it's just better to crash and then fix
>> it if we end up there.
>>
>>>>
>>>> - if (!already_streaming)
>>>> + if (!use_s_stream && !already_streaming)
>>>> v4l2_subdev_enable_privacy_led(sd);
>>>
>>> Once everybody switches to v4l2_subdev_enable_streams() (am I dreaming?)
>>> we should move LED handling from the .s_stream() wrapper to here for the
>>> fallback case too. How about a TODO comment ?
>>
>> Let's get back to this after we figure out if s_stream can ever be removed.
>>
>>>>
>>>> done:
>>>> - v4l2_subdev_unlock_state(state);
>>>> + if (!use_s_stream)
>>>
>>> if (state)
>>>
>>> would be better I think.
>>
>> We get the state and state lock if (!use_s_stream), so I think it makes
>> sense to use the same condition when unlocking to be symmetric. I'm sure
>> I can be convinced to use if (state) too, though =).
>>
>> Tomi
>>
>>>> + 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 the 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);
>>>
>>> Do we want to disable the privacy LED on failure in all cases, in
>>> particular when the .s_stream() or .disable_streams() operations are not
>>> even called ?
>>>
>>> And now that I wrote that, I realize the !v4l2_subdev_is_streaming()
>>> condition will not be true if the operations failed, so it should be
>>> fine.
>>>
>>> Reviewed-by: Laurent Pinchart <[email protected]>
>>>
>>>>
>>>> - v4l2_subdev_unlock_state(state);
>>>> + v4l2_subdev_unlock_state(state);
>>>> + }
>>>>
>>>> return ret;
>>>> }
>>>>
>>>
>>
>

2024-04-24 14:11:08

by Tomi Valkeinen

[permalink] [raw]

Subject: Re: [PATCH v5 09/10] media: subdev: Support single-stream case in v4l2_subdev_enable/disable_streams()

On 24/04/2024 16:17, Laurent Pinchart wrote:
> On Wed, Apr 24, 2024 at 04:11:36PM +0300, Tomi Valkeinen wrote:
>> On 24/04/2024 16:09, Laurent Pinchart wrote:
>>> On Wed, Apr 24, 2024 at 04:05:31PM +0300, Tomi Valkeinen wrote:
>>>> On 19/04/2024 18:36, Laurent Pinchart wrote:
>>>>> On Tue, Apr 16, 2024 at 04:55:12PM +0300, 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:
>>>>>>
>>>>>> - 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.
>>>>>>
>>>>>
>>>>> Now that v4l2_subdev_enable_streams() is usable by (almost) every
>>>>> driver, should we update documentation to indicate that manual calls to
>>>>> .s_stream() should be avoided ?
>>>>
>>>> How about:
>>>>
>>>> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
>>>> index dabe1b5dfe4a..f52bb790773c 100644
>>>> --- a/include/media/v4l2-subdev.h
>>>> +++ b/include/media/v4l2-subdev.h
>>>> @@ -450,6 +450,11 @@ enum v4l2_subdev_pre_streamon_flags {
>>>> * already started or stopped subdev. Also see call_s_stream wrapper in
>>>> * v4l2-subdev.c.
>>>> *
>>>> + * New drivers should instead implement &v4l2_subdev_pad_ops.enable_streams
>>>> + * and &v4l2_subdev_pad_ops.disable_streams operations, and use
>>>> + * v4l2_subdev_s_stream_helper for the &v4l2_subdev_video_ops.s_stream
>>>> + * operation to support legacy users.A
>>>> + *
>>>
>>> Add
>>>
>>> * Drivers should also not call the .s_stream() subdev operation directly,
>>> * but use the v4l2_subdev_enable_streams() and
>>> * v4l2_subdev_disable_streams() helpers.
>>>
>>>> * @g_pixelaspect: callback to return the pixelaspect ratio.
>>>> *
>>>> * @s_dv_timings: Set custom dv timings in the sub device. This is used
>>>>
>>>>
>>>> Although now that I think about it, can we "ever" get rid of s_stream?
>>>> enable_streams is only usable if the subdev has pads.
>>>
>>> Do we have pad-less subdevs that can stream ?
>>
>> Probably not, but isn't s_stream used to enable any type of subdev? Or
>> is there a different op to power on padless subdevs?
>
> .s_stream() is supposed to start/stop streaming, and you can't really
> have streams without pads, as they have to come from/go somewhere.

Ok. I was under the impression that .s_stream() is also used to enable
non-streaming subdevs when the pipeline's streaming is started. If
that's not the case, I'll update the doc.

Tomi

>>>> If that's the
>>>> case, the text above should probably clarify when one should continue
>>>> using s_stream.
>>>>
>>>>>> Signed-off-by: Tomi Valkeinen <[email protected]>
>>>>>> ---
>>>>>> 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 e45fd42da1e3..10406acfb9d0 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);
>>>>>> + *enabled_streams =
>>>>>> + (sd->enabled_pads & BIT_ULL(pad)) ? BIT_ULL(0) : 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 the 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);
>>>>>
>>>>> state gets set to a non-null value above if the subdev has an
>>>>> enable_streams operation, while in v4l2_subdev_set_streams_enabled(),
>>>>
>>>> That's not quite true, v4l2_subdev_lock_and_get_active_state() returns
>>>> NULL if there's no state. If the driver has .enable_streams but no
>>>> subdev-state, we'll have NULL state. But is that a driver bug? Probably,
>>>> although I'm not quite sure. Whereas V4L2_SUBDEV_FL_STREAMS without
>>>> state is a driver bug.
>>>>
>>>>> you use it if the V4L2_SUBDEV_FL_STREAMS flag is set. The second
>>>>> condition is a subset of the first one, so it should be safe now, but I
>>>>> wonder if we're at risk of crashes in the future when reworking the
>>>>> code. I'm probably worrying needlessly.
>>>>
>>>> I agree that this is a bit messy. We have multiple different scenarios
>>>> which we handle in the same functions, and it's somewhat unclear what
>>>> op/state/flag combinations the drivers are allowed to have and what not.
>>>>
>>>> I could add a !state check here, and then use sd->enabled_pads. But that
>>>> doesn't feel correct, and I think it's just better to crash and then fix
>>>> it if we end up there.
>>>>
>>>>>>
>>>>>> - if (!already_streaming)
>>>>>> + if (!use_s_stream && !already_streaming)
>>>>>> v4l2_subdev_enable_privacy_led(sd);
>>>>>
>>>>> Once everybody switches to v4l2_subdev_enable_streams() (am I dreaming?)
>>>>> we should move LED handling from the .s_stream() wrapper to here for the
>>>>> fallback case too. How about a TODO comment ?
>>>>
>>>> Let's get back to this after we figure out if s_stream can ever be removed.
>>>>
>>>>>>
>>>>>> done:
>>>>>> - v4l2_subdev_unlock_state(state);
>>>>>> + if (!use_s_stream)
>>>>>
>>>>> if (state)
>>>>>
>>>>> would be better I think.
>>>>
>>>> We get the state and state lock if (!use_s_stream), so I think it makes
>>>> sense to use the same condition when unlocking to be symmetric. I'm sure
>>>> I can be convinced to use if (state) too, though =).
>>>>
>>>>>> + 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 the 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);
>>>>>
>>>>> Do we want to disable the privacy LED on failure in all cases, in
>>>>> particular when the .s_stream() or .disable_streams() operations are not
>>>>> even called ?
>>>>>
>>>>> And now that I wrote that, I realize the !v4l2_subdev_is_streaming()
>>>>> condition will not be true if the operations failed, so it should be
>>>>> fine.
>>>>>
>>>>> Reviewed-by: Laurent Pinchart <[email protected]>
>>>>>
>>>>>>
>>>>>> - v4l2_subdev_unlock_state(state);
>>>>>> + v4l2_subdev_unlock_state(state);
>>>>>> + }
>>>>>>
>>>>>> return ret;
>>>>>> }
>>>>>>
>