[libcamera-devel] [PATCH 1/3] vimc: Add usage count to subdevices
Dafna Hirschfeld
dafna3 at gmail.com
Mon Dec 2 17:16:50 CET 2019
Hi,
On Sat, May 18, 2019 at 4:16 AM Niklas Söderlund <
niklas.soderlund+renesas at ragnatech.se> wrote:
> Prepare for multiple video streams from the same sensor by adding a use
> counter to each subdevice. The counter is increase for every s_stream(1)
> and decremented for every s_stream(0) call.
>
> The subdevice stream is not started or stopped unless the usage count go
> from 0 to 1 (started) or from 1 to 0 (stopped). This allow for multiple
> s_stream() calls to try to either start or stop the device while only
> the first/last call will actually effect the state of the device.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
> drivers/media/platform/vimc/vimc-debayer.c | 8 ++++++++
> drivers/media/platform/vimc/vimc-scaler.c | 8 ++++++++
> drivers/media/platform/vimc/vimc-sensor.c | 7 +++++++
> 3 files changed, 23 insertions(+)
>
> diff --git a/drivers/media/platform/vimc/vimc-debayer.c
> b/drivers/media/platform/vimc/vimc-debayer.c
> index 281f9c1a7249ad1d..624fc23ce3077d40 100644
> --- a/drivers/media/platform/vimc/vimc-debayer.c
> +++ b/drivers/media/platform/vimc/vimc-debayer.c
> @@ -56,6 +56,7 @@ struct vimc_deb_device {
> struct vimc_ent_device ved;
> struct v4l2_subdev sd;
> struct device *dev;
> + atomic_t use_count;
> /* The active format */
> struct v4l2_mbus_framefmt sink_fmt;
> u32 src_code;
> @@ -337,6 +338,9 @@ static int vimc_deb_s_stream(struct v4l2_subdev *sd,
> int enable)
> const struct v4l2_format_info *pix_info;
> unsigned int frame_size;
>
> + if (atomic_inc_return(&vdeb->use_count) != 1)
> + return 0;
> +
>
I guess the use_count should decrease in case this function fails to
allocate the frame,this also applies to the other s_stream callbacks in
this patch.
>
> if (vdeb->src_frame)
> return 0;
>
> @@ -374,6 +378,9 @@ static int vimc_deb_s_stream(struct v4l2_subdev *sd,
> int enable)
> return -ENOMEM;
>
> } else {
> + if (atomic_dec_return(&vdeb->use_count) != 0)
> + return 0;
> +
> if (!vdeb->src_frame)
> return 0;
>
> @@ -562,6 +569,7 @@ static int vimc_deb_comp_bind(struct device *comp,
> struct device *master,
> vdeb->ved.process_frame = vimc_deb_process_frame;
> dev_set_drvdata(comp, &vdeb->ved);
> vdeb->dev = comp;
> + atomic_set(&vdeb->use_count, 0);
>
> /* Initialize the frame format */
> vdeb->sink_fmt = sink_fmt_default;
> diff --git a/drivers/media/platform/vimc/vimc-scaler.c
> b/drivers/media/platform/vimc/vimc-scaler.c
> index 8aecf8e920310608..37d2020d987a7d80 100644
> --- a/drivers/media/platform/vimc/vimc-scaler.c
> +++ b/drivers/media/platform/vimc/vimc-scaler.c
> @@ -45,6 +45,7 @@ struct vimc_sca_device {
> struct vimc_ent_device ved;
> struct v4l2_subdev sd;
> struct device *dev;
> + atomic_t use_count;
> /* NOTE: the source fmt is the same as the sink
> * with the width and hight multiplied by mult
> */
> @@ -213,6 +214,9 @@ static int vimc_sca_s_stream(struct v4l2_subdev *sd,
> int enable)
> const struct v4l2_format_info *pix_info;
> unsigned int frame_size;
>
> + if (atomic_inc_return(&vsca->use_count) != 1)
> + return 0;
> +
> if (vsca->src_frame)
> return 0;
>
> @@ -242,6 +246,9 @@ static int vimc_sca_s_stream(struct v4l2_subdev *sd,
> int enable)
> return -ENOMEM;
>
> } else {
> + if (atomic_dec_return(&vsca->use_count) != 0)
> + return 0;
> +
> if (!vsca->src_frame)
> return 0;
>
> @@ -396,6 +403,7 @@ static int vimc_sca_comp_bind(struct device *comp,
> struct device *master,
> vsca->ved.process_frame = vimc_sca_process_frame;
> dev_set_drvdata(comp, &vsca->ved);
> vsca->dev = comp;
> + atomic_set(&vsca->use_count, 0);
>
> /* Initialize the frame format */
> vsca->sink_fmt = sink_fmt_default;
> diff --git a/drivers/media/platform/vimc/vimc-sensor.c
> b/drivers/media/platform/vimc/vimc-sensor.c
> index baca9ca67ce0af0b..36c3cea85a185f4b 100644
> --- a/drivers/media/platform/vimc/vimc-sensor.c
> +++ b/drivers/media/platform/vimc/vimc-sensor.c
> @@ -34,6 +34,7 @@ struct vimc_sen_device {
> struct vimc_ent_device ved;
> struct v4l2_subdev sd;
> struct device *dev;
> + atomic_t use_count;
> struct tpg_data tpg;
> struct task_struct *kthread_sen;
> u8 *frame;
> @@ -197,6 +198,9 @@ static int vimc_sen_s_stream(struct v4l2_subdev *sd,
> int enable)
> const struct v4l2_format_info *pix_info;
> unsigned int frame_size;
>
> + if (atomic_inc_return(&vsen->use_count) != 1)
> + return 0;
> +
> if (vsen->kthread_sen)
> /* tpg is already executing */
> return 0;
> @@ -218,6 +222,8 @@ static int vimc_sen_s_stream(struct v4l2_subdev *sd,
> int enable)
> vimc_sen_tpg_s_format(vsen);
>
> } else {
> + if (atomic_dec_return(&vsen->use_count) != 0)
> + return 0;
>
> vfree(vsen->frame);
> vsen->frame = NULL;
> @@ -367,6 +373,7 @@ static int vimc_sen_comp_bind(struct device *comp,
> struct device *master,
> vsen->ved.process_frame = vimc_sen_process_frame;
> dev_set_drvdata(comp, &vsen->ved);
> vsen->dev = comp;
> + atomic_set(&vsen->use_count, 0);
>
> /* Initialize the frame format */
> vsen->mbus_format = fmt_default;
> --
>
maybe it is enough to check if the entity.pipe pointer of each vimc
subdevice is NULL, since the media-contoller
follows the streaming count with stream_count field and set the pipe
pointer to null if it is 0.Then there is no need
to add use_count field to each vimc entity.
Thanks,
Dafna
> 2.21.0
>
>
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