From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Antonino A. Daplas" Subject: Re: VESA, EDID & flat panels Date: Tue, 04 Oct 2005 15:59:34 +0800 Message-ID: <43423666.8090001@gmail.com> References: <1128380013.8267.125.camel@gaston> <8a0c36780510031618m48c55f45u648d867bcf0130d2@mail.gmail.com> <1128397436.31063.0.camel@gaston> <434220D0.3020101@gmail.com> <1128407961.31063.50.camel@gaston> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1EMhjO-00079Z-Qo for linux-fbdev-devel@lists.sourceforge.net; Tue, 04 Oct 2005 01:00:58 -0700 Received: from xproxy.gmail.com ([66.249.82.201]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1EMhjM-000888-N1 for linux-fbdev-devel@lists.sourceforge.net; Tue, 04 Oct 2005 01:00:59 -0700 Received: by xproxy.gmail.com with SMTP id i28so330507wxd for ; Tue, 04 Oct 2005 01:00:44 -0700 (PDT) In-Reply-To: <1128407961.31063.50.camel@gaston> Sender: linux-fbdev-devel-admin@lists.sourceforge.net Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: Benjamin Herrenschmidt Cc: linux-fbdev-devel@lists.sourceforge.net Benjamin Herrenschmidt wrote: >> It think it's because the (basic) EDID is retrieved with (basic) DDC >> (address 0x50). If I'm not mistaken, E-EDID is retrieved with E-DDC >> (address 0xa0). I don't exactly know the protocol (E-DDDC specs are not >> freely available), but try probing your i2c busses with: >> >> i2cdump 0,1,2,etc 0xa0 >> >> and see if you get anything. > > Are you sure we aren't talking about the same address here ? Address > 0xa0 _is_ 0x50 shifted one bit left ... (The low bit of an i2c address > is the RW bit). i2cdump takes shifted addresses, thus you can't pass it > anything above 0x7f, thus passing it 0x50 is what gives you address > 0xa0 :) > > Ben. > > > Here's a snippet from the HDMI specs. Not sure how helpful this is "8.4.3 Segment pointer Enhanced DDC allows access of up to 32 Kbytes of data. This is accomplished using a combination of the 0xA0/0xA1 address pair and a segment pointer. For each value of the segment pointer, 256 bytes of data are available at the 0xA0/0xA1 address pair. An unspecified segment pointer references the same data as when the segment pointer is zero. Each successive value of the segment pointer allows access to the next two blocks of E-EDID (128 bytes each). The value of the segment pointer register cannot be read since it is reset at the completion of each command." Tony ------------------------------------------------------- This SF.Net email is sponsored by: Power Architecture Resource Center: Free content, downloads, discussions, and more. http://solutions.newsforge.com/ibmarch.tmpl