Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 24 Apr 2024 16:11:36 +0300 | Subject | Re: [PATCH v5 09/10] media: subdev: Support single-stream case in v4l2_subdev_enable/disable_streams() | From | Tomi Valkeinen <> |
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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 <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 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 <laurent.pinchart@ideasonboard.com> >>> >>>> >>>> - v4l2_subdev_unlock_state(state); >>>> + v4l2_subdev_unlock_state(state); >>>> + } >>>> >>>> return ret; >>>> } >>>> >>> >> >
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