Re: [PATCH] video: ARM CLCD: Added support for FBIOPAN_DISPLAY and virtual y resolution

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:

quoted

On Mon, Mar 02, 2015 at 04:08:29PM +0000, Pawel Moll wrote:

quoted

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

quoted

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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