Re: [PATCH v4 4/6] media: max9286: Use routes to configure link order

Jacopo Mondi
2021-12-17T13:37:28Z

Hi Laurent,

On Fri, Dec 17, 2021 at 04:35:19AM +0200, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Thu, Dec 16, 2021 at 06:47:44PM +0100, 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
> > 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.
>
> I wonder if we could drop some of the configuration from
> max9286_setup().

Do you mean move it to a later time ?

>
> > 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 1395eb783dc0..5d728fa23f01 100644
> > --- a/drivers/media/i2c/max9286.c
> > +++ b/drivers/media/i2c/max9286.c
> > @@ -499,6 +499,61 @@ 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];
> > +
> > + if (!(priv->route_mask & BIT(i)))
> > + continue;
>
> Is this check needed ?
>

It is, I need to first assign a VC to the enabled routes.
I could replace it with for_each_active_route() probably!

> > +
> > + /* 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;
>
> You can use __ffs(), which counts from 0 (but has an undefined behaviour
> when no bit is set).

That's why I didn't want to use it :)

>
> > + 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
> > */
> > @@ -700,6 +755,8 @@ 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
> > @@ -1108,32 +1165,6 @@ 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.
> > *
> > @@ -1143,13 +1174,7 @@ 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);
> >
> > /*
> > * Video format setup:
> > @@ -1321,12 +1346,6 @@ 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.
> > @@ -1337,6 +1356,12 @@ 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;
> > + }
> > +
> > ret = max9286_i2c_mux_init(priv);
> > if (ret) {
> > dev_err(dev, "Unable to initialize I2C multiplexer\n");
>
> --
> Regards,
>
> Laurent Pinchart