From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sam Ravnborg Subject: Re: [RFC PATCH 0/7] add at91sam9 LCDC DRM driver Date: Fri, 24 Aug 2018 17:52:46 +0200 Message-ID: <20180824155246.GB26678@ravnborg.org> References: <20180812184152.GA22343@ravnborg.org> <20180824102233.73852596@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <20180824102233.73852596@bbrezillon> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Boris Brezillon Cc: Mark Rutland , devicetree@vger.kernel.org, Alexandre Belloni , linux-pwm@vger.kernel.org, Nicolas Ferre , dri-devel@lists.freedesktop.org, Rob Herring , Lee Jones , linux-arm-kernel@lists.infradead.org List-Id: linux-pwm@vger.kernel.org SGkgQm9yaXMuCgo+ID4gCj4gPiBCb3RoIGRldmljZXMgYXJlIHN1cHBvcnRlZCB0b2RheSBieSB0 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aW5nIGxpc3QKZHJpLWRldmVsQGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpodHRwczovL2xpc3RzLmZy ZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2RyaS1kZXZlbAo= From mboxrd@z Thu Jan 1 00:00:00 1970 From: sam@ravnborg.org (Sam Ravnborg) Date: Fri, 24 Aug 2018 17:52:46 +0200 Subject: [RFC PATCH 0/7] add at91sam9 LCDC DRM driver In-Reply-To: <20180824102233.73852596@bbrezillon> References: <20180812184152.GA22343@ravnborg.org> <20180824102233.73852596@bbrezillon> Message-ID: <20180824155246.GB26678@ravnborg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Boris. > > > > Both devices are supported today by the atmel_lcdfb driver. > > For this new set of drivers the compatible strings was > > selected to avoid clash with the existing compatible > > strings used for the atmel_lcdfb driver to allow them > > to co-exist. > > Hm, I think Rob commented on that already, but we usually try to stay > compatible with the exisiting/old bindings when introducing a new one. > Don't know how feasible this is in this particular case though. I v2 I am working with a backward compatible approach. This is better that what I cam up with initially. > > The DRM implementation has a few shortcomings compared to the > > existing fbdev based driver: > > - STN displays are not supported > > Binding support is missing but most of the > > STN specific functionality is otherwise ported > > from the fbdev driver. > > I assume the info should come from the panel > > but as I lack HW I have not looked too much > > into what is required. > > - gamma support is missing > > The driver utilises drm_simple_kms_helper and > > this helper lacks support for setting up gamma. > > If this is useful please let me know and I > > will extend drm_simple_kms_helper to support this > > and update the driver. > > I guess you can skip that for now. Also based on feedback from Nicholas the STN parts will be dropped in v2. For the gamma stuff this looks feasible with a small extension to drm_simple_kms_helper - but I dunno if this is something that userspace will actually use. So that will wait until there is some good reason to implement it, and I know how to test it too. > > > - modesetting is not checked (see TODO in file) > > Is this required for such a simple setup? > > Well, that's always better if you can check that the requested display > mode is supported before trying to apply it. I will try to cook up something, have learned a little since posting v1. > > > - support for extra modes as applicable (and lcd-wiring-mode) > > Peter already suggested something I think. Yep, plenty of links to read. Sam