[PATCH V4] drm: edid: add support for E-DDC

[Shirish S]

On Wed, Aug 29, 2012 at 4:08 AM, Ville Syrjälä <
ville.syrjala at linux.intel.com> wrote:

> On Sat, Aug 25, 2012 at 03:13:56PM +0530, Shirish S wrote:
> > The current logic for probing ddc is limited to
> > 2 blocks (256 bytes), this patch adds support
> > for the 4 block (512) data.
> >
> > To do this, a single 8-bit segment index is
> > passed to the display via the I2C address 30h.
> > Data from the selected segment is then immediately
> > read via the regular DDC2 address using a repeated
> > I2C 'START' signal.
> >
> > Signed-off-by: Shirish S <s.shirish at samsung.com>
> > ---
> >  drivers/gpu/drm/drm_edid.c |   22 ++++++++++++++++++----
> >  1 files changed, 18 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index a8743c3..cde7af0 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -254,6 +254,8 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
> unsigned char *buf,
> >                     int block, int len)
> >  {
> >       unsigned char start = block * EDID_LENGTH;
> > +     unsigned char segment = block >> 1;
> > +     unsigned char xfers = segment ? 3 : 2;
> >       int ret, retries = 5;
> >
> >       /* The core i2c driver will automatically retry the transfer if the
> > @@ -264,7 +266,12 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
> unsigned char *buf,
> >        */
> >       do {
> >               struct i2c_msg msgs[] = {
> > -                     {
> > +                     { /*set segment pointer */
>
> Missing whitespace after '/*'. Perhaps just drop the comment. I don't
> see much value in it.
>
> Done.

> > +                             .addr   = DDC_SEGMENT_ADDR,
> > +                             .flags  = segment ? 0 : I2C_M_IGNORE_NAK,
> > +                             .len    = 1,
> > +                             .buf    = &segment,
> > +                     }, {
> >                               .addr   = DDC_ADDR,
> >                               .flags  = 0,
> >                               .len    = 1,
> > @@ -276,15 +283,22 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
> unsigned char *buf,
> >                               .buf    = buf,
> >                       }
> >               };
> > -             ret = i2c_transfer(adapter, msgs, 2);
> > +     /* Avoid sending the segment addr to not upset non-compliant ddc
> > +      * monitors.
> > +      */
>
> Wrong indentation and comment style is wrong. I'm guessing this didn't go
> through checkpatch.pl.
>
> I never got tha above as either an error or warning in the checkpatch,
anyways have uploaded patch set 5 incorporating your comments.

> Otherwise looks OK to me.
>
> --
> Ville Syrjälä
> Intel OTC
>

- Shirish

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