Re: [PATCH/RFC v2 10/15] adv748x: csi2: add translation from pixelcode to CSI-2 datatype

[jacopo mondi <jacopo@jmondi.org>]

Hi Kieran,

On Thu, Dec 14, 2017 at 10:25:36PM +0000, Kieran Bingham wrote:
> Hi Niklas,
>
> On 14/12/17 19:08, Niklas Söderlund wrote:
> > This will be needed to fill out the frame descriptor information
> > correctly.
> >
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> > ---
> >  drivers/media/i2c/adv748x/adv748x-csi2.c | 22 ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> >
> > diff --git a/drivers/media/i2c/adv748x/adv748x-csi2.c b/drivers/media/i2c/adv748x/adv748x-csi2.c
> > index 2a5dff8c571013bf..a2a6d93077204731 100644
> > --- a/drivers/media/i2c/adv748x/adv748x-csi2.c
> > +++ b/drivers/media/i2c/adv748x/adv748x-csi2.c
> > @@ -18,6 +18,28 @@
> >
> >  #include "adv748x.h"
> >
> > +struct adv748x_csi2_format {
> > +	unsigned int code;
> > +	unsigned int datatype;
> > +};
> > +
> > +static const struct adv748x_csi2_format adv748x_csi2_formats[] = {
> > +	{ .code = MEDIA_BUS_FMT_RGB888_1X24,    .datatype = 0x24, },
> > +	{ .code = MEDIA_BUS_FMT_UYVY8_1X16,     .datatype = 0x1e, },
> > +	{ .code = MEDIA_BUS_FMT_UYVY8_2X8,      .datatype = 0x1e, },
> > +	{ .code = MEDIA_BUS_FMT_YUYV10_2X10,    .datatype = 0x1e, },

YUV 422 10 bit is associated to data type 0x1d in CSI-2 specifications

> > +};
>
> Is the datatype mapping specific to the ADV748x here?
> or are these generic/common CSI2 mappings?
>
> What do those datatype magic numbers represent?

They are fixed mappings defined by CSI-2 specifications and they
should probably be generic to all drivers imho

>
> --
> Kieran
>
> > +
> > +static unsigned int adv748x_csi2_code_to_datatype(unsigned int code)
> > +{
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(adv748x_csi2_formats); i++)
> > +		if (adv748x_csi2_formats[i].code == code)
> > +			return adv748x_csi2_formats[i].datatype;
> > +	return 0;
> > +}
> > +
> >  static bool is_txa(struct adv748x_csi2 *tx)
> >  {
> >  	return tx == &tx->state->txa;
> >