[PATCH 1/2 v2] drm/pl111: Support the Versatile Express

[Liviu Dudau]

On Wed, Apr 18, 2018 at 12:50:10PM +0100, Robin Murphy wrote:
> On 17/04/18 20:31, Linus Walleij wrote:
> > On Tue, Apr 17, 2018 at 3:12 PM, Robin Murphy <robin.murphy at arm.com> wrote:
> > > On 17/04/18 13:32, Linus Walleij wrote:
> > > [...]
> > > > 
> > > > Unfortunately there is just one single vexpress core tile in the
> > > > upstream kernel that define a CLCD controller, the CA9 (4xA9)
> > > > that I am using. All the others just use the MB CLCD.
> > > > 
> > > > I am thinking there is some never finished DTS upstreaming
> > > > here that ought to happen so we use the core tile CLCD on some
> > > > other boards as well.
> > > 
> > > 
> > > Barring custom FPGA images, I think V2P-CA9 *is* the only VExpress tile
> > > implementing PL11x; all the more recent test chips had HDLCD instead.
> > 
> > Yup it looks like that.
> > 
> > I am restructuring the code to look for any graphics on the
> > core tile and only turn on the motherboard CLCD if there is
> > no CLCD or HDLCD on the core tile, e.g. if that device node has
> > been set to "disabled" or the HDLCD driver is not compiled in
> > but the CLCD driver is.
> > 
> > I found some vague mentions of a LCD display that can be
> > connected to the motherboard, so that would then be sitting
> > on the CLCD, is this something you ARM guys have seen
> > around? In that case I guess the VExpress (etc) would actually
> > be able to have two screens, one LCD panel on the motherboard
> > CLCD and a DVI from the core tile.
> 
> I don't see anything in the V2M motherboard manual to suggest the IOFPGA
> CLCD output is routed anywhere other than the DVI mux, and there are
> certainly no unaccounted-for connectors on the VExpress version currently in
> front of me (HBI-0190D). The only things I'm immediately aware of having a
> panel connector directly on the board are Integrator/CP and RealView EB.

Yes, I think the last platform that could have had an LCD display
attached directly was the Versatile platform, not the VExpress one.

Regarding the mux and trying to figure out a clever way of deciding
which one should have priority: I would not bother adding that to the
CLCD driver, instead I would expect the bootloader to set the MUX
correctly. Long time ago, before Juno was a thing and the only platform
HDLCD was running on was VExpress, I did have a patch to use
vexpress_config_write() (API before vexpress-config got converted to
regmap) to set the MUX. Then Juno happened and I've realised it was not
worth baking into the driver the existence of the MUX, as it was a quirk
of the board.

Best regards,
Liviu

> 
> Robin.

-- 
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