From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guennadi Liakhovetski Date: Thu, 24 Mar 2011 19:13:27 +0000 Subject: Re: [RFC PATCH] HDMI:Support for EDID parsing in kernel. Message-Id: List-Id: References: <1300815176-21206-1-git-send-email-mythripk@ti.com> <20110323081820.5b37d169@jbarnes-desktop> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: "K, Mythri P" Cc: Jesse Barnes , Dave Airlie , linux-fbdev@vger.kernel.org, linux-omap@vger.kernel.org, dri-devel , linux-media@vger.kernel.org On Thu, 24 Mar 2011, K, Mythri P wrote: > Hi Jesse, >=20 > On Wed, Mar 23, 2011 at 8:48 PM, Jesse Barnes = wrote: > > On Wed, 23 Mar 2011 18:58:27 +0530 > > "K, Mythri P" wrote: > > > >> Hi Dave, > >> > >> On Wed, Mar 23, 2011 at 6:16 AM, Dave Airlie wrote: > >> > On Wed, Mar 23, 2011 at 3:32 AM, Mythri P K wrote: > >> >> Adding support for common EDID parsing in kernel. > >> >> > >> >> EDID - Extended display identification data is a data structure pro= vided by > >> >> a digital display to describe its capabilities to a video source, T= his a > >> >> standard supported by CEA and VESA. > >> >> > >> >> There are several custom implementations for parsing EDID in kernel= , some > >> >> of them are present in fbmon.c, drm_edid.c, sh_mobile_hdmi.c, Ideal= ly > >> >> parsing of EDID should be done in a library, which is agnostic of t= he > >> >> framework (V4l2, DRM, FB) =A0which is using the functionality, just= based on > >> >> the raw EDID pointer with size/segment information. > >> >> > >> >> With other RFC's such as the one below, which tries to standardize = HDMI API's > >> >> It would be better to have a common EDID code in one place.It also = helps to > >> >> provide better interoperability with variety of TV/Monitor may be e= ven by > >> >> listing out quirks which might get missed with several custom imple= mentation > >> >> of EDID. > >> >> http://permalink.gmane.org/gmane.linux.drivers.video-input-infrastr= ucture/30401 > >> >> > >> >> This patch tries to add functions to parse some portion EDID (detai= led timing, > >> >> monitor limits, AV delay information, deep color mode support, Audi= o and VSDB) > >> >> If we can align on this library approach i can enhance this library= to parse > >> >> other blocks and probably we could also add quirks from other imple= mentation > >> >> as well. > >> >> > >> > > >> > If you want to take this approach, you need to start from the DRM ED= ID parser, > >> > its the most well tested and I can guarantee its been plugged into m= ore monitors > >> > than any of the others. There is just no way we would move the DRM p= arser to a > >> > library one that isn't derived from it + enhancements, as we'd throw= away the > >> > years of testing and the regression count would be way too high. > >> > > >> I had a look at the DRM EDID code, but for quirks it looks pretty much= the same. > >> yes i could take quirks and other DRM tested code and enhance, but > >> still the code has to do away with struct drm_display_mode > >> which is very much custom to DRM. > > > > If that's the only issue you have, we could easily rename that > > structure or add conversion funcs to a smaller structure if that's what > > you need. > > > > Dave's point is that we can't ditch the existing code without > > introducing a lot of risk; it would be better to start a library-ized > > EDID codebase from the most complete one we have already, i.e. the DRM > > EDID code. Does the DRM EDID-parser also process blocks beyond the first one and=20 also parses SVD entries similar to what I've recently added to fbdev? Yes, = we definitely need a common EDID parses, and maybe we'll have to collect=20 various pieces from different implementations. Thanks Guennadi > > > This sounds good. If we can remove the DRM dependent portion to have a > library-ized EDID code, > That would be perfect. The main Intention to have a library is, > Instead of having several different Implementation in kernel, all > doing the same EDID parsing , if we could have one single > implementation , it would help in better testing and interoperability. >=20 > > Do you really think the differences between your code and the existing > > DRM code are irreconcilable? > > > On the contrary if there is a library-ized EDID parsing using the > drm_edid, and there is any delta / fields( Parsing the video block in > CEA extension for Short Video Descriptor, Vendor block for AV delay > /Deep color information etc) that are parsed with the RFC i posted i > would be happy to add. >=20 > Thanks and regards, > Mythri. > > -- > > Jesse Barnes, Intel Open Source Technology Center > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >=20 --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/