On 19/04/2024 18:36, Laurent Pinchart wrote:
Hi Tomi, Thank you for the patch. 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. + * * @g_pixelaspect: callback to return the pixelaspect ratio. * * @s_dv_timings: Set custom dv timings in the sub device. This is usedAlthough now that I think about it, can we "ever" get rid of s_stream? enable_streams is only usable if the subdev has pads. 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@xxxxxxxxxxxxxxxx> --- 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@xxxxxxxxxxxxxxxx>- v4l2_subdev_unlock_state(state);+ v4l2_subdev_unlock_state(state); + }return ret;}
