From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Date: Mon, 02 Mar 2015 19:12:13 +0000 Subject: Re: [PATCH] video: ARM CLCD: Added support for FBIOPAN_DISPLAY and virtual y resolution Message-Id: <20150302191212.GT8656@n2100.arm.linux.org.uk> List-Id: References: <1424898082-1522-1-git-send-email-arun.ramamurthy@broadcom.com> <1424898082-1522-2-git-send-email-arun.ramamurthy@broadcom.com> <1425312509.3092.7.camel@arm.com> <20150302161122.GP8656@n2100.arm.linux.org.uk> <54F4B57F.3030306@broadcom.com> In-Reply-To: <54F4B57F.3030306@broadcom.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Arun Ramamurthy Cc: Pawel Moll , Rob Herring , Mark Rutland , Ian Campbell , Kumar Gala , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-fbdev@vger.kernel.org" , Dmitry Torokhov , Anatol Pomazau , Jonathan Richardson , Scott Branden , Ray Jui , "bcm-kernel-feedback-list@broadcom.com" On Mon, Mar 02, 2015 at 11:09:51AM -0800, Arun Ramamurthy wrote: > > > On 15-03-02 08:11 AM, Russell King - ARM Linux wrote: > >On Mon, Mar 02, 2015 at 04:08:29PM +0000, Pawel Moll wrote: > >>I'm not sure about this... The word "virtual" never works well with > >>device tree nodes defined as "hardware description". > >> > >>I understand what you're doing, but adding this property to the display > >>controller's node doesn't sound right. How does this describe hardware? > >>If anywhere, it's more like a job for the panel node? > > > I see what you are saying Pawel, I can follow Russell's recommendation of > adding a RAM size node called max-memory-available or something similar > >A better description (and implementation) would be to describe the size > >of the RAM available for video purposes. The driver can then use the > >requested virtual X resolution to limit (and/or compute) the virtual Y > >resolution to allow Y panning/wrapping of the display. > > > > In this scenario, where would I specify the virtual X resolution? I am > assuming it would be in the panel-timing node as Pawel suggested? virtual X should default to real X if it's not set, otherwise it should come from the selected mode. Drivers which get this right are things like acornfb, where we've used ywrap scolling since it was merged. -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net.