Hi Kieran,
On Wed, Mar 18, 2020 at 09:50:22AM +0000, Kieran Bingham wrote:
> Hi Jacopo,
>
> On 16/03/2020 20:27, Jacopo Mondi wrote:
> > Parse the 'maxim,overlap-window' property value and cache its
> > content to later program registers 0x63 and 0x64.
> >
> > As specified by the bindings documentation, the property is mandatory as
> > long as a default value cannot be established to guarantee DTB backward
> > compatibility.
>
> Well, we don't yet have the DTB bindings 'in' I don't believe so I don't
> think we need to worry about backwards compatibility yet...
>
> Oh, or do you mean in the future it wouldn't have to be mandatory
> perhaps ...
I meant in future. As we don't know now what an opportune default is
for this un-documented setting, I think having all DTBs using this
first version fully specified will make any decision we take in future
easier to implement in a back-ward compatible way.
>
> >
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> > ---
> > drivers/media/i2c/max9286.c | 26 ++++++++++++++++++++++++++
> > 1 file changed, 26 insertions(+)
> >
> > diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> > index 06edd8bd3e82..0357515860b2 100644
> > --- a/drivers/media/i2c/max9286.c
> > +++ b/drivers/media/i2c/max9286.c
> > @@ -117,6 +117,9 @@
> > #define MAX9286_REV_FLEN(n) ((n) - 20)
> > /* Register 0x49 */
> > #define MAX9286_VIDEO_DETECT_MASK 0x0f
> > +/* Register 0x64 */
> > +#define MAX9286_OVLP_WINDOWH_MASK GENMASK(4, 0)
> > +
> > /* Register 0x69 */
> > #define MAX9286_LFLTBMONMASKED BIT(7)
> > #define MAX9286_LOCKMONMASKED BIT(6)
> > @@ -164,6 +167,8 @@ struct max9286_priv {
> > unsigned int csi2_data_lanes;
> > struct max9286_source sources[MAX9286_NUM_GMSL];
> > struct v4l2_async_notifier notifier;
> > +
> > + u32 overlap_window;
> > };
> >
> > static struct max9286_source *next_source(struct max9286_priv *priv,
> > @@ -895,6 +900,11 @@ static int max9286_setup(struct max9286_priv *priv)
> > max9286_write(priv, 0x01, MAX9286_FSYNCMODE_INT_HIZ |
> > MAX9286_FSYNCMETH_AUTO);
> >
> > + /* Configure overlap window. */
> > + max9286_write(priv, 0x63, priv->overlap_window);
> > + max9286_write(priv, 0x64, (priv->overlap_window >> 8) &
> > + MAX9286_OVLP_WINDOWH_MASK);
> > +
> > /* Enable HS/VS encoding, use D14/15 for HS/VS, invert VS. */
> > max9286_write(priv, 0x0c, MAX9286_HVEN | MAX9286_INVVS |
> > MAX9286_HVSRC_D14);
> > @@ -1041,8 +1051,24 @@ static int max9286_parse_dt(struct max9286_priv *priv)
> > struct device_node *i2c_mux;
> > struct device_node *node = NULL;
> > unsigned int i2c_mux_mask = 0;
> > + int ret;
> >
> > of_node_get(dev->of_node);
> > +
> > + /*
> > + * FIXM: Require overlap window value to be specified by DTS as long as
>
> /FIXM/FIXME/
>
> > + * the control function is not clarified. As soon as a default
> > + * behaviour can be established drop this requirement, while older
>
> /established/established,/
> /requirement,/requirement/
>
>
> > + * DTBs are guaranteed to be fully specified.
> > + */
> > + ret = of_property_read_u32(dev->of_node, "maxim,overlap-window",
> > + &priv->overlap_window);
> > + if (ret) {
> > + dev_err(dev, "Missing property \"maxim,overlap-window\"\n");
> > + of_node_put(dev->of_node);
> > + return -EINVAL;
> > + }
> > +
>
> Other wise, this looks fine except for my concerns and wondering if this
> could be approached by defining a property of the requirements in the
> serializer and parsing that in some form.
As per my previous reply, I had the same concern but mostly for the
reverse channel setting. This is a configuration that applies solely
to the deserializer (at least, that's my understanding not knowing
exactly what this property controls)
>
>
> --
> Kieran
>
> > i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
> > if (!i2c_mux) {
> > dev_err(dev, "Failed to find i2c-mux node\n");
> >
>
