Re: [PATCH v4 3/6] media: max9286: Use enabled routes to calculate pixelrate

Laurent Pinchart
2021-12-17T02:29:56Z

Hi Jacopo,

Thank you for the patch.

On Thu, Dec 16, 2021 at 06:47:43PM +0100, Jacopo Mondi wrote:
> Now that the device supports routing, use the enabled routes instead
> of the connected sources to compute the output pixel rate.
>
> To do so, update the route_mask after a set_routing() call with the
> ACTIVE format, and re-calculate the pixel rate just after.
>
> At the same time, start and stop only the enabled routes at s_stream()
> time.
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
> drivers/media/i2c/max9286.c | 63 ++++++++++++++++++++++++++++++-------
> 1 file changed, 51 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> index eb76acdb2cd9..1395eb783dc0 100644
> --- a/drivers/media/i2c/max9286.c
> +++ b/drivers/media/i2c/max9286.c
> @@ -188,8 +188,11 @@ struct max9286_priv {
> struct v4l2_async_notifier notifier;
> };
>
> +#define to_index(priv, source) ((source) - &(priv)->sources[0])
> +
> static struct max9286_source *next_source(struct max9286_priv *priv,
> - struct max9286_source *source)
> + struct max9286_source *source,
> + bool routed)
> {
> if (!source)
> source = &priv->sources[0];
> @@ -197,17 +200,27 @@ static struct max9286_source *next_source(struct max9286_priv *priv,
> source++;
>
> for (; source < &priv->sources[MAX9286_NUM_GMSL]; source++) {
> - if (source->fwnode)
> + unsigned int index = to_index(priv, source);
> +
> + if (!source->fwnode)
> + continue;
> +
> + /*
> + * Careful here! A very unfortunate call to set_routing() can
> + * change priv->route_mask behind our back!
> + */

This seems error-prone. I wonder if we could instead remove route_mask
completely, and compute it as .s_stream(1) time by walking the routes
from the state. That would avoid storing state information in
max9286_priv.

The downside is that we'll have to pass the route mask down to functions
called by max9286_s_stream(). At some point in the future, I'd like to
see support for subclassing the subdev state in subdev drivers, at which
point we will be able to cache the route_mask in the subclassed state
when configuring routing, and reusing the cached value when starting the
streams.

> + if (!routed || priv->route_mask & BIT(index))
> return source;
> }
>
> return NULL;
> }
>
> -#define for_each_source(priv, source) \
> - for ((source) = NULL; ((source) = next_source((priv), (source))); )
> +#define for_each_route(priv, source) \
> + for ((source) = NULL; ((source) = next_source((priv), (source), true)); )
>
> -#define to_index(priv, source) ((source) - &(priv)->sources[0])
> +#define for_each_source(priv, source) \
> + for ((source) = NULL; ((source) = next_source((priv), (source), false)); )
>
> static inline struct max9286_priv *sd_to_max9286(struct v4l2_subdev *sd)
> {
> @@ -409,7 +422,7 @@ static int max9286_check_video_links(struct max9286_priv *priv)
> if (ret < 0)
> return -EIO;
>
> - if ((ret & MAX9286_VIDEO_DETECT_MASK) == priv->source_mask)
> + if ((ret & MAX9286_VIDEO_DETECT_MASK) == priv->route_mask)
> break;
>
> usleep_range(350, 500);
> @@ -493,9 +506,10 @@ static int max9286_check_config_link(struct max9286_priv *priv,
> static int max9286_set_pixelrate(struct max9286_priv *priv)
> {
> struct max9286_source *source = NULL;
> + unsigned int num_routes = 0;
> u64 pixelrate = 0;
>
> - for_each_source(priv, source) {
> + for_each_route(priv, source) {
> struct v4l2_ctrl *ctrl;
> u64 source_rate = 0;
>
> @@ -516,6 +530,8 @@ static int max9286_set_pixelrate(struct max9286_priv *priv)
> "Unable to calculate pixel rate\n");
> return -EINVAL;
> }
> +
> + num_routes++;
> }
>
> if (!pixelrate) {
> @@ -529,7 +545,7 @@ static int max9286_set_pixelrate(struct max9286_priv *priv)
> * by the number of available sources.
> */
> return v4l2_ctrl_s_ctrl_int64(priv->pixelrate,
> - pixelrate * priv->nsources);
> + pixelrate * num_routes);
> }
>
> static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
> @@ -691,8 +707,8 @@ static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
> */
> max9286_i2c_mux_open(priv);
>
> - /* Start all cameras. */
> - for_each_source(priv, source) {
> + /* Start cameras. */
> + for_each_route(priv, source) {
> ret = v4l2_subdev_call(source->sd, video, s_stream, 1);
> if (ret)
> return ret;
> @@ -733,8 +749,8 @@ static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
> } else {
> max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
>
> - /* Stop all cameras. */
> - for_each_source(priv, source)
> + /* Stop cameras. */
> + for_each_route(priv, source)
> v4l2_subdev_call(source->sd, video, s_stream, 0);
>
> max9286_i2c_mux_close(priv);
> @@ -912,6 +928,29 @@ static int max9286_set_routing(struct v4l2_subdev *sd,
> v4l2_subdev_lock_state(state);
>
> ret = _max9286_set_routing(sd, state, routing);
> + if (ret)
> + goto out;
> +
> + if (which == V4L2_SUBDEV_FORMAT_TRY)
> + goto out;
> +
> + /*
> + * Update the active routes mask and the pixel rate according to the
> + * routed sources.
> + */
> + priv->route_mask = 0;
> + for (i = 0; i < routing->num_routes; ++i) {
> + struct v4l2_subdev_route *route = &routing->routes[i];
> +
> + if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
> + continue;
> +
> + priv->route_mask |= BIT(route->sink_pad);
> + }
> +
> + max9286_set_pixelrate(priv);
> +
> +out:
> v4l2_subdev_unlock_state(state);
>
> return ret;

--
Regards,

Laurent Pinchart