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Date: Mon, 2 Mar 2015 19:12:13 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Arun Ramamurthy <arun.ramamurthy@broadcom.com>
Cc: Pawel Moll <pawel.moll@arm.com>, Rob Herring <robh+dt@kernel.org>,
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Subject: Re: [PATCH] video: ARM CLCD: Added support for FBIOPAN_DISPLAY and
 virtual y resolution
Message-ID: <20150302191212.GT8656@n2100.arm.linux.org.uk>
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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.

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