Re: [PATCH v2 04/13] media: max9286: Use routes to configure link order

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

On Sat, Jan 22, 2022 at 03:14:33AM +0200, Laurent Pinchart wrote:
> On Sun, Oct 17, 2021 at 08:24:40PM +0200, Jacopo Mondi wrote:
> > Use the routing table to configure the link output order and link
> > masking.
> > 
> > The link output order defines the CSI-2 virtual channel a GSML stream
> 
> s/GSML/GMSL/
> 
> > is output on. Configure ordering at stream start time and at chip
> > setup time. This last step requires to move the chip initialization
> > function after the V4L2 setup phase as it requires the subdev state from
> > where the routing table is retrieved from to be initialized.
> > 
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > ---
> >  drivers/media/i2c/max9286.c | 103 ++++++++++++++++++++++--------------
> >  1 file changed, 64 insertions(+), 39 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> > index 2e635179aec0..3485478f08a5 100644
> > --- a/drivers/media/i2c/max9286.c
> > +++ b/drivers/media/i2c/max9286.c
> > @@ -500,6 +500,61 @@ static int max9286_check_config_link(struct max9286_priv *priv,
> >  	return 0;
> >  }
> >  
> > +/*
> > + * Configure the links output order (which defines on which CSI-2 VC a
> > + * link is output on) and configure link masking.
> > + */
> > +static void max9286_config_links(struct max9286_priv *priv)
> > +{
> > +	const struct v4l2_subdev_krouting *routing;
> > +	struct v4l2_subdev_state *state;
> > +	u8 link_order = 0;
> > +	u8 vc_mask = 0xf;
> > +	unsigned int i;
> > +
> > +	state = v4l2_subdev_lock_active_state(&priv->sd);
> > +	routing = &state->routing;
> > +
> > +	for (i = 0; i < routing->num_routes; ++i) {
> > +		struct v4l2_subdev_route *route = &routing->routes[i];

And I think we should also ignore disabled routes, so using

	for_each_active_route(&state->routing, route) {

is likely better too.

> > +
> > +		if (!(priv->route_mask & BIT(i)))
> 
> Shouldn't this be BIT(route->sink_pad), has route_mask stores a bitmask
> of sink pads (see max9286_set_routing()) ?
> 
> > +			continue;
> > +
> > +		/* Assign the CSI-2 VC using the source stream number. */
> > +		link_order |= route->source_stream << (2 * route->sink_pad);
> > +		vc_mask &= ~BIT(route->source_stream);
> > +	}
> > +
> > +	/*
> > +	 * This might look rather silly, but now that we have assigned a
> > +	 * VC to the enabled routes, we have to assign one to the disabled
> > +	 * routes as well, as there cannot be two sources with the same VC.
> > +	 */
> > +	for (i = 0; i < MAX9286_NUM_GMSL; ++i) {
> > +		unsigned int vc;
> > +
> > +		if (priv->route_mask & BIT(i))
> > +			continue;
> > +
> > +		/* ffs() counts from 1. */
> > +		vc = ffs(vc_mask) - 1;
> > +		link_order |= vc << (2 * i);
> > +		vc_mask &= ~BIT(vc);
> > +	}
> > +
> > +	/*
> > +	 * Use the enabled routes to enable GMSL links, configure the CSI-2
> > +	 * output order, mask unused links and autodetect link used as CSI
> > +	 * clock source.
> > +	 */
> > +	max9286_write(priv, 0x00, MAX9286_MSTLINKSEL_AUTO | priv->route_mask);
> > +	max9286_write(priv, 0x0b, link_order);
> > +	max9286_write(priv, 0x69, 0xf & ~priv->route_mask);
> > +
> > +	v4l2_subdev_unlock_state(state);
> > +}
> > +
> >  /* -----------------------------------------------------------------------------
> >   * V4L2 Subdev
> >   */
> > @@ -701,6 +756,8 @@ static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
> >  	int ret;
> >  
> >  	if (enable) {
> > +		max9286_config_links(priv);
> > +
> >  		/*
> >  		 * The frame sync between cameras is transmitted across the
> >  		 * reverse channel as GPIO. We must open all channels while
> > @@ -1109,32 +1166,6 @@ static void max9286_v4l2_unregister(struct max9286_priv *priv)
> >  
> >  static int max9286_setup(struct max9286_priv *priv)
> >  {
> > -	/*
> > -	 * Link ordering values for all enabled links combinations. Orders must
> > -	 * be assigned sequentially from 0 to the number of enabled links
> > -	 * without leaving any hole for disabled links. We thus assign orders to
> > -	 * enabled links first, and use the remaining order values for disabled
> > -	 * links are all links must have a different order value;
> > -	 */
> > -	static const u8 link_order[] = {
> > -		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxxx */
> > -		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxx0 */
> > -		(3 << 6) | (2 << 4) | (0 << 2) | (1 << 0), /* xx0x */
> > -		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xx10 */
> > -		(3 << 6) | (0 << 4) | (2 << 2) | (1 << 0), /* x0xx */
> > -		(3 << 6) | (1 << 4) | (2 << 2) | (0 << 0), /* x1x0 */
> > -		(3 << 6) | (1 << 4) | (0 << 2) | (2 << 0), /* x10x */
> > -		(3 << 6) | (1 << 4) | (1 << 2) | (0 << 0), /* x210 */
> > -		(0 << 6) | (3 << 4) | (2 << 2) | (1 << 0), /* 0xxx */
> > -		(1 << 6) | (3 << 4) | (2 << 2) | (0 << 0), /* 1xx0 */
> > -		(1 << 6) | (3 << 4) | (0 << 2) | (2 << 0), /* 1x0x */
> > -		(2 << 6) | (3 << 4) | (1 << 2) | (0 << 0), /* 2x10 */
> > -		(1 << 6) | (0 << 4) | (3 << 2) | (2 << 0), /* 10xx */
> > -		(2 << 6) | (1 << 4) | (3 << 2) | (0 << 0), /* 21x0 */
> > -		(2 << 6) | (1 << 4) | (0 << 2) | (3 << 0), /* 210x */
> > -		(3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* 3210 */
> > -	};
> > -
> >  	/*
> >  	 * Set the I2C bus speed.
> >  	 *
> > @@ -1144,13 +1175,7 @@ static int max9286_setup(struct max9286_priv *priv)
> >  	max9286_configure_i2c(priv, true);
> >  	max9286_reverse_channel_setup(priv, priv->init_rev_chan_mv);
> >  
> > -	/*
> > -	 * Enable GMSL links, mask unused ones and autodetect link
> > -	 * used as CSI clock source.
> > -	 */
> > -	max9286_write(priv, 0x00, MAX9286_MSTLINKSEL_AUTO | priv->route_mask);
> > -	max9286_write(priv, 0x0b, link_order[priv->route_mask]);
> > -	max9286_write(priv, 0x69, (0xf & ~priv->route_mask));
> > +	max9286_config_links(priv);
> 
> We could actually skip this, and only call
> 
> 	max9286_write(priv, 0x00, MAX9286_MSTLINKSEL_AUTO | priv->route_mask);
> 
> to enable the links. The link order and link masking is only needed when
> starting the streams, which is done by calling max9286_config_links() in
> max9286_s_stream().
> 
> >  
> >  	/*
> >  	 * Video format setup:
> > @@ -1324,12 +1349,6 @@ static int max9286_init(struct device *dev)
> >  	if (ret)
> >  		return ret;
> >  
> > -	ret = max9286_setup(priv);
> > -	if (ret) {
> > -		dev_err(dev, "Unable to setup max9286\n");
> > -		goto err_poc_disable;
> > -	}
> > -
> >  	/*
> >  	 * Register all V4L2 interactions for the MAX9286 and notifiers for
> >  	 * any subdevices connected.
> > @@ -1340,6 +1359,12 @@ static int max9286_init(struct device *dev)
> >  		goto err_poc_disable;
> >  	}
> >  
> > +	ret = max9286_setup(priv);
> > +	if (ret) {
> > +		dev_err(dev, "Unable to setup max9286\n");
> > +		goto err_poc_disable;
> > +	}
> > +
> 
> And with the above change, I think you can keep the max9286_setup() call
> where it was.
> 
> >  	ret = max9286_i2c_mux_init(priv);
> >  	if (ret) {
> >  		dev_err(dev, "Unable to initialize I2C multiplexer\n");

-- 
Regards,

Laurent Pinchart