[Intel-gfx] [PATCH] detect hdmi monitor by reading edid

Ma, Ling ling.ma at intel.com
Tue Jun 30 07:44:22 CEST 2009

>-----Original Message-----
>From: intel-gfx-bounces at lists.freedesktop.org
>[mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of Keith Packard
>Sent: 2009年6月29日 23:07
>To: Ma, Ling
>Cc: intel-gfx at lists.freedesktop.org
>Subject: Re: [Intel-gfx] [PATCH] detect hdmi monitor by reading edid
>On Mon, 2009-06-29 at 14:41 +0800, ling.ma at intel.com wrote:
>> We detect HDMI output status by setting interrupt enable bit,
>> then read interrupt status, which is effective for most cases.
>> However G4x platform will indicate incorrect detection result
>> even if current output is HDMI monitor. The patch intends
>> to read edid, then determin connect status by EDID type.
>Can you describe the precise errors in detection you're seeing here?
>From my experience, as the hotplug bits are shared among multiple
>outputs, they will never provide a false-positive reading.
We run into two related bugs #21322 and #21084
For #21322, The G43 can not find dvi monitor by hot plug approach.
For #21084   There are 2 root causes, one is in KMS Q45( DQ45EK in our lab)  connected by VGA through DVI-I can't fetch EDID info, another is the it will mistake VGA as HDMI monitor.
Our original approach is to set Hot Plug Interrupt Detect Enable, then read corresponding live state bit. However According to the HW team, live status detection need special board design, and won't work on all boards.
Meanwhile I ever have seen bios code for G4X always read first 4 bytes of EDID to detect HDMI monitor and not use hot plug approach. 

Ma Ling
>keith.packard at intel.com

More information about the Intel-gfx mailing list