Re: [PATCH 3/4] media: subdev: Improve v4l2_subdev_enable/disable_streams_fallback
From: Tomi Valkeinen
Date: Thu Apr 04 2024 - 08:41:09 EST
On 04/04/2024 15:18, Sakari Ailus wrote:
Moi,
Thanks for the patch.
On Thu, Apr 04, 2024 at 01:50:02PM +0300, Tomi Valkeinen wrote:
v4l2_subdev_enable/disable_streams_fallback() supports falling back to
.s_stream() for subdevs with a single source pad. It also tracks the
enabled streams for that one pad in the sd->enabled_streams field.
Tracking the enabled streams with sd->enabled_streams does not make
sense, as with .s_stream() there can only be a single stream per pad.
Thus, as the v4l2_subdev_enable/disable_streams_fallback() only supports
a single source pad, all we really need is a boolean which tells whether
streaming has been enabled on this pad or not.
However, as we only need a true/false state for a pad (instead of
tracking which streams have been enabled for a pad), we can easily
extend the fallback mechanism to support multiple source pads as we only
need to keep track of which pads have been enabled.
Change the sd->enabled_streams field to sd->enabled_pads, which is a
64-bit bitmask tracking the enabled source pads. With this change we can
remove the restriction that
v4l2_subdev_enable/disable_streams_fallback() only supports a single
soruce pad.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-subdev.c | 68 ++++++++++++++++++++---------------
include/media/v4l2-subdev.h | 9 +++--
2 files changed, 44 insertions(+), 33 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 3b3310bce5d4..91298bb84e6b 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -2090,37 +2090,43 @@ 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;
- unsigned int i;
int ret;
/*
* The subdev doesn't implement pad-based stream enable, fall back
- * on the .s_stream() operation. This can only be done for subdevs that
- * have a single source pad, as sd->enabled_streams is global to the
- * subdev.
+ * on the .s_stream() operation.
*/
if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
return -EOPNOTSUPP;
- for (i = 0; i < sd->entity.num_pads; ++i) {
- if (i != pad && sd->entity.pads[i].flags & MEDIA_PAD_FL_SOURCE)
- return -EOPNOTSUPP;
- }
+ /*
+ * .s_stream() means there is no streams support, so only allowed stream
+ * is the imlicit 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) * 8)
s/8/BITS_PER_BYTE/
+ return -EOPNOTSUPP;
- if (sd->enabled_streams & streams_mask) {
- dev_dbg(dev, "set of streams %#llx already enabled on %s:%u\n",
- streams_mask, sd->entity.name, pad);
+ 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 streams are enabled. */
- if (!sd->enabled_streams) {
+ /* 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_streams |= streams_mask;
+ sd->enabled_pads |= BIT_ULL(pad);
return 0;
}
@@ -2207,37 +2213,43 @@ static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
u64 streams_mask)
{
struct device *dev = sd->entity.graph_obj.mdev->dev;
- unsigned int i;
int ret;
/*
- * If the subdev doesn't implement pad-based stream enable, fall back
- * on the .s_stream() operation. This can only be done for subdevs that
- * have a single source pad, as sd->enabled_streams is global to the
- * subdev.
+ * If the subdev doesn't implement pad-based stream enable, fall back
+ * on the .s_stream() operation.
*/
if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
return -EOPNOTSUPP;
- for (i = 0; i < sd->entity.num_pads; ++i) {
- if (i != pad && sd->entity.pads[i].flags & MEDIA_PAD_FL_SOURCE)
- return -EOPNOTSUPP;
- }
+ /*
+ * .s_stream() means there is no streams support, so only allowed stream
+ * is the imlicit 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) * 8)
Ditto.
How much of the code of the two functions is the same? Could some of this
be put to a common function both would call? They look (almost) exactly the
same.
v4l2_subdev_enable_streams_fallback and v4l2_subdev_enable_streams? They
have similar parts, but I don't right away see how combining them or
making some common functions would help.
Tomi
+ return -EOPNOTSUPP;
- if ((sd->enabled_streams & streams_mask) != streams_mask) {
- dev_dbg(dev, "set of streams %#llx already disabled on %s:%u\n",
- streams_mask, sd->entity.name, pad);
+ if ((sd->enabled_pads & BIT_ULL(pad)) != 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_streams & ~streams_mask)) {
+ if (!(sd->enabled_pads & ~BIT_ULL(pad))) {
ret = v4l2_subdev_call(sd, video, s_stream, 0);
if (ret)
return ret;
}
- sd->enabled_streams &= ~streams_mask;
+ sd->enabled_pads &= ~BIT_ULL(pad);
return 0;
}
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 8bd1e3c96d2b..7077aec3176c 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -1039,10 +1039,9 @@ struct v4l2_subdev_platform_data {
* @active_state: Active state for the subdev (NULL for subdevs tracking the
* state internally). Initialized by calling
* v4l2_subdev_init_finalize().
- * @enabled_streams: Bitmask of enabled streams used by
- * v4l2_subdev_enable_streams() and
- * v4l2_subdev_disable_streams() helper functions for fallback
- * cases.
+ * @enabled_pads: Bitmask of enabled pads used by 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.
*
* Each instance of a subdev driver should create this struct, either
@@ -1091,7 +1090,7 @@ struct v4l2_subdev {
* doesn't support it.
*/
struct v4l2_subdev_state *active_state;
- u64 enabled_streams;
+ u64 enabled_pads;
bool streaming_enabled;
};