Hello Daniel, <div class="gmail_quote">On Tue, Aug 21, 2012 at 4:18 AM, Daniel Vetter <<a href="mailto:daniel@ffwll.ch" target="_blank">daniel@ffwll.ch</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> On Tue, Aug 21, 2012 at 9:10 AM, Shirish S <<a href="mailto:s.shirish@samsung.com">s.shirish@samsung.com</a>> 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 <<a href="mailto:s.shirish@samsung.com">s.shirish@samsung.com</a>> > --- > drivers/gpu/drm/drm_edid.c | 17 ++++++++++++----- > 1 files changed, 12 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index a8743c3..2c2996e 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 short segFlags = segment ? 0 : I2C_M_IGNORE_NAK; Have you tested this on i915 with gmbus enabled? I'm asking since we don't implement the IGNORE_NAK flag and hence I'd expect spurious failures on displays that don't support E-DDC ... </blockquote>I have verified this on samsung exynos5 platform, and it passed the HDMI compliance test for the same. I also verified this on HDMI analyser- Agilent N5988A , this analyser does not support 4 block EDID data(EDDC), it passed in this analyser as well. Is there any specific reason why you dont implement IGNORE_NAK? Infact if i think for EDDC, if one does not pass IGNORE_NAK flag it might give errors. <div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Cheers, Daniel > int ret, retries = 5; > > /* The core i2c driver will automatically retry the transfer if the > @@ -264,27 +266,32 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf, > */ > do { > struct i2c_msg msgs[] = { > - { > + { /*set segment pointer */ > + .addr = DDC_SEGMENT_ADDR, > + .flags = segFlags, > + .len = 1, > + .buf = &start, > + }, { /*set offset */ > .addr = DDC_ADDR, > .flags = 0, > .len = 1, > .buf = &start, > - }, { > + }, { /*set data */ > .addr = DDC_ADDR, > .flags = I2C_M_RD, > .len = len, > .buf = buf, > } > }; > - ret = i2c_transfer(adapter, msgs, 2); > + ret = i2c_transfer(adapter, msgs, 3); > if (ret == -ENXIO) { > DRM_DEBUG_KMS("drm: skipping non-existent adapter %s\n", > adapter->name); > break; > } > - } while (ret != 2 && --retries); > + } while (ret != 3 && --retries); > > - return ret == 2 ? 0 : -1; > + return ret == 3 ? 0 : -1; > } > > static bool drm_edid_is_zero(u8 *in_edid, int length) > -- > 1.7.0.4 > > _______________________________________________ > dri-devel mailing list > <a href="mailto:dri-devel@lists.freedesktop.org">dri-devel@lists.freedesktop.org</a> > <a href="http://lists.freedesktop.org/mailman/listinfo/dri-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/dri-devel</a> -- Daniel Vetter <a href="mailto:daniel.vetter@ffwll.ch">daniel.vetter@ffwll.ch</a> - +41 (0) 79 364 57 48 - <a href="http://blog.ffwll.ch" target="_blank">http://blog.ffwll.ch</a> _______________________________________________ dri-devel mailing list <a href="mailto:dri-devel@lists.freedesktop.org">dri-devel@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/dri-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/dri-devel</a> </blockquote></div>Regards,<div>Shirish S</div>