[Intel-gfx] [PATCH] drm/i915: Delete the strict EDID check for SDVO DVI-D monitor

[ykzhao]

On Thu, 2009-10-22 at 15:15 +0800, Keith Packard wrote:
> Excerpts from yakui.zhao's message of Thu Oct 22 14:25:33 +0900 2009:
> > From: Zhao Yakui <yakui.zhao at intel.com>
> > 
> > In theory we can use EDID obtained from the DVI-D monitor to detect whether
> > the device is connected or not.
> 
> The DVI spec *requires* EDID on DVI-D monitors. Do we have any
> information on why this is failing? Perhaps our EDID code is broken
> for some monitors?
This issue happens on one SDVO card with multiple inputs and multiple
outputs.

At first IMO maybe this is related with the incorrect DDC bus behind
SDVO card. I write a debug patch which tries to read 128byte by using
different DDC bus.(PROM, DDC1, DDC2, DDC3).
Unfortunately it can read nothing even when the different DDC bus is
used. It always reports that there doesn't exist the 0xA0 slave address.

But one bug reporter can read the EDID by using the
read-edid-tool(1.4.2), which is realized by using BIOS call. 

It is very interesting. Maybe our I2C bus code is different with that
used in Video-BIOS.

Thanks.
    Yakui.

>