[PATCH V5] drm: edid: add support for E-DDC

[Shirish S]

Thanks for the comments Daniel and Jean
I will upload patch set 6.
This shall include Jean's review coments.
And i will tag Daniel,Jean and Ville as reviewed.

Regards,
Shirish S

On Wed, Aug 29, 2012 at 9:12 AM, Daniel Vetter <daniel at ffwll.ch> wrote:

> On Wed, Aug 29, 2012 at 4:46 PM, Shirish S <s.shirish at samsung.com> 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>
>
> If you resend patches it'd be nice to keep a changelog of the patch
> itself somewhere, otherwise it's just more work to figure that out for
> reviewers. Also, you can usually attach reviewed-by tags (like mine)
> to a patch resend if you don't change the patch massively ...
> -Daniel
>
> > ---
> >  drivers/gpu/drm/drm_edid.c |   22 +++++++++++++++++++---
> >  1 files changed, 19 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index bcc4725..b9ffc30 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
> > @@ -265,6 +267,11 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter,
> unsigned char *buf,
> >         do {
> >                 struct i2c_msg msgs[] = {
> >                         {
> > +                               .addr   = DDC_SEGMENT_ADDR,
> > +                               .flags  = segment ? 0 : I2C_M_IGNORE_NAK,
> > +                               .len    = 1,
> > +                               .buf    = &segment,
> > +                       }, {
> >                                 .addr   = DDC_ADDR,
> >                                 .flags  = 0,
> >                                 .len    = 1,
> > @@ -276,15 +283,24 @@ 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.
> > +        */
> > +               if (!segment)
> > +                       ret = i2c_transfer(adapter, &msgs[1], xfers);
> > +               else
> > +                       ret = i2c_transfer(adapter, msgs, xfers);
> > +
> >                 if (ret == -ENXIO) {
> >                         DRM_DEBUG_KMS("drm: skipping non-existent
> adapter %s\n",
> >                                         adapter->name);
> >                         break;
> >                 }
> > -       } while (ret != 2 && --retries);
> > +       } while (ret != xfers && --retries);
> >
> > -       return ret == 2 ? 0 : -1;
> > +       return ret == xfers ? 0 : -1;
> >  }
> >
> >  static bool drm_edid_is_zero(u8 *in_edid, int length)
> > --
> > 1.7.0.4
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
>
>
> --
> Daniel Vetter
> daniel.vetter at ffwll.ch - +41 (0) 79 364 57 48 - http://blog.ffwll.ch
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
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