From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH] tegra: ventana: display and backlight DT entries Date: Wed, 14 Nov 2012 07:55:25 +0100 Message-ID: <20121114065525.GA12629@avionic-0098.mockup.avionic-design.de> References: <1352802204-1740-1-git-send-email-acourbot@nvidia.com> <20121113123410.GA11202@avionic-0098.mockup.avionic-design.de> <50A2797C.9030807@wwwdotorg.org> <1393946.fMW2YXfOao@percival> <50A3329D.8000708@nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="qMm9M+Fa2AknHoGS" Return-path: Content-Disposition: inline In-Reply-To: <50A3329D.8000708-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Zhang Cc: Alex Courbot , Stephen Warren , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org --qMm9M+Fa2AknHoGS Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Nov 14, 2012 at 01:56:45PM +0800, Mark Zhang wrote: > On 11/14/2012 01:36 PM, Alex Courbot wrote: > > On Wednesday 14 November 2012 00:46:52 Stephen Warren wrote: > >> I do tend to think that we should use EDID where there is one. > >> > >> 1) If there is an EDID in the panel HW, and the panel's I2C is hooked > >> up to Tegra, we should read it out at runtime. > >=20 > > According to Ventana' platform design guide the LCD panel is hooked on = I2C2.=20 > > The panel's data sheet lists CLK_EDID and DATA_EDID pins, which I assum= e are=20 > > for I2C, but there is no mention of an I2C address in both guides. > >=20 >=20 > Normally the address is 0x50. Take a look at function > "drm_do_probe_ddc_edid" as a reference. >=20 > >> 2) Otherwise, if the panel's documentation provides an EDID, we should > >> use that, since it's the most canonical/common/standard representation > >> of the panel's properties. > >=20 > > Panel's documentation indeed provides full EDID specification in append= ix. Mark=20 > > sent me an EDID blob which works but I don't know where it comes from -= Mark,=20 > > could you tell us? > >=20 >=20 > Actually I use a tool named "i2cget" to get this 128 bytes EDID. For > Ventana, I use a script like this: >=20 > for i in $(seq 0 127) > do > #echo " Reading byte no : $i " > i2cget -y 0 0x50 $i | xxd -r -p >> tegra20-ventana.edid > done There is also i2cdump but I suppose for writing the data into a binary file it isn't as well suited as the above loop. I seem to remember a tool that could be used to dump EDID directly, but I can't get a fix on the name. Anyway, if you can get the EDID data that way it should also be possible to get it directly within tegra-drm. Thierry --qMm9M+Fa2AknHoGS Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIcBAEBAgAGBQJQo0BdAAoJEN0jrNd/PrOhOCIQAKg4eu/wQjDRQ8MeTPEyKOiU 2RcNifZpFzXEFzvNBa1K3CQJUV1Xi8prr1fzMLps3YxJiWNCpgJJymqVhtyu/YcP f1Z0Z/J3bZ9wZitqHgwSHK5OyZ9a2Gza0B/xumfyFvRecUyztCzeDdf9m71hcUDd el2CpbRk4Stdrkc70CtzO62EnNyD+gfp32+YHnBnLZsqYAfNGNxyhWfCtf1+3n50 9J5h1Da+XCvWK5OPX/FWnjwKn6wv0/thBFde9z/8lT2qd0i5CMdAEJ2TJgz/S8DF aI8h9Te0s5BA8RsMktfq/E81gmGaEgqsBtZS1ycXCtw0mqv4D+YBk7unMZPDDafs 20Dm5/FGfh+A+qrd9s1blhvBLQ/dv+OJHoQZF0M2NutJ/DH7mm1zXKmDSE/GzXmg Fs78MrmufNlEYP215nRcSPAhSOTnofi4iU08+jnzWQgNqS0bam6+RAgOQ9gQpqQK 9lXcgj2OZRLdxpQ52Oj2Nzpb8IXh99biyUxsvtXqWVRJv9G0F7fR46d55CNT86mK UtZRHI2aGHtW2/UQJWIS3Sr3gKPYOwswcoVHNEpIbtvuDGkHj50xN7Y5oyowEIjp bWMH0lAAVdKjDcwJIvdj35Mq5TcpN/eubI6PQgUA24/wIitJdnQTIqprm7BSOeaD X5d9D3QNDvSyUiaDKtpM =afK0 -----END PGP SIGNATURE----- --qMm9M+Fa2AknHoGS--