From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751432AbdBALfo (ORCPT ); Wed, 1 Feb 2017 06:35:44 -0500 Received: from mail-wm0-f68.google.com ([74.125.82.68]:35205 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751259AbdBALfl (ORCPT ); Wed, 1 Feb 2017 06:35:41 -0500 Date: Wed, 1 Feb 2017 12:35:36 +0100 From: Daniel Vetter To: Peter Senna Tschudin Cc: Archit Taneja , ijc+devicetree@hellion.org.uk, Fabio Estevam , treding@nvidia.com, linux-kernel@vger.kernel.org, davem@davemloft.net, mark.rutland@arm.com, ykk@rock-chips.com, martin.donnelly@ge.com, mchehab@osg.samsung.com, robh+dt@kernel.org, galak@codeaurora.org, peter.senna@gmail.com, pawel.moll@arm.com, javier@dowhile0.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org, shawnguo@kernel.org, Peter Senna Tschudin , tiwai@suse.com, linux@roeck-us.net, martyn.welch@collabora.co.uk, rmk+kernel@armlinux.org.uk, kernel@pengutronix.de, daniel.vetter@ffwll.ch, jslaby@suse.cz, devicetree@vger.kernel.org, linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org, enric.balletbo@collabora.com, dri-devel@lists.freedesktop.org, Jani Nikula Subject: Re: [PATCH V7 3/4] drm/bridge: Add driver for GE B850v3 LVDS/DP++ Bridge Message-ID: <20170201113536.dig22kidlw6mjoz5@phenom.ffwll.local> Mail-Followup-To: Peter Senna Tschudin , Archit Taneja , ijc+devicetree@hellion.org.uk, Fabio Estevam , treding@nvidia.com, linux-kernel@vger.kernel.org, davem@davemloft.net, mark.rutland@arm.com, ykk@rock-chips.com, martin.donnelly@ge.com, mchehab@osg.samsung.com, robh+dt@kernel.org, galak@codeaurora.org, peter.senna@gmail.com, pawel.moll@arm.com, javier@dowhile0.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org, shawnguo@kernel.org, Peter Senna Tschudin , tiwai@suse.com, linux@roeck-us.net, martyn.welch@collabora.co.uk, rmk+kernel@armlinux.org.uk, kernel@pengutronix.de, jslaby@suse.cz, devicetree@vger.kernel.org, linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org, enric.balletbo@collabora.com, dri-devel@lists.freedesktop.org, Jani Nikula References: <64ff-5891bf80-f-117f65c0@159002012> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <64ff-5891bf80-f-117f65c0@159002012> X-Operating-System: Linux phenom 4.8.0-1-amd64 User-Agent: NeoMutt/20161126 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 01, 2017 at 10:58:43AM +0000, Peter Senna Tschudin wrote: > Hi Archit, > > On 01 February, 2017 10:44 CET, Archit Taneja wrote: > > > > > > > On 01/30/2017 10:35 PM, Jani Nikula wrote: > > > On Sat, 28 Jan 2017, Peter Senna Tschudin wrote: > > >> On Thu, Jan 05, 2017 at 01:18:47PM +0530, Archit Taneja wrote: > > >> Hi Archit, > > >> > > >> Thank you for the comments! > > >> > > >> [...] > > >>>> + total_size = (block[EDID_EXT_BLOCK_CNT] + 1) * EDID_LENGTH; > > >>>> + if (total_size > EDID_LENGTH) { > > >>>> + kfree(block); > > >>>> + block = kmalloc(total_size, GFP_KERNEL); > > >>>> + if (!block) > > >>>> + return NULL; > > >>>> + > > >>>> + /* Yes, read the entire buffer, and do not skip the first > > >>>> + * EDID_LENGTH bytes. > > >>>> + */ > > >>> > > >>> Is this the reason why you aren't using drm_do_get_edid()? > > > >> > > >> Yes, for some hw specific reason, it is necessary to read the entire > > >> EDID buffer starting from 0, not block by block. > > > > > > Hrmh, I'm planning on moving the edid override and firmware edid > > > mechanisms at the drm_do_get_edid() level to be able to truly and > > > transparently use a different edid. Currently, they're only used for > > > modes, really, and lead to some info retrieved from overrides, some from > > > the real edid. This kind of hacks will bypass the override/firmware edid > > > mechanisms then too. :( > > > > It seems like there is a HW issue which prevents them from reading EDID > > from an offset. So, I'm not sure if it is a hack or a HW limitation. > > > > > One way around this would be to hide the HW requirement in the > > get_edid_block func pointer passed to drm_do_get_edid(). This > > would, however, result in more i2c reads (equal to # of extension > > blocks) than what the patch currently does. > > > > Peter, if you think doing extra EDID reads isn't too costly on your > > platform, you could consider using drm_do_get_edid(). If not, I guess > > you'll miss out on the additional functionality Jani is going to add > > > in the future. > > My concern is that for almost one year now, every time I fix something > one or two new requests are made. I'm happy to fix the driver, but I > want a list of the changes that are required to get it upstream, before > I make more changes. Can we agree on exactly what is preventing this > driver to get upstream? Then I'll fix it. I think addressing this edid reading question post-merge is perfectly fine. Aside, want to keep maintaing your stuff as part of the drm-misc group, with the drivers-in-misc experiment? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch