On Mon, Jun 23, 2014 at 02:52:15PM +0100, Pawel Moll wrote:

On Fri, 2014-06-20 at 23:27 +0100, Peter Maydell wrote:

quoted

How does this work for boards like the versatilepb which have a
mux between a PL110 and the TFT, allowing it to efffectively
rewire the pads at runtime under control of the SYS_CLCD
sysreg (to give a wider range of colour modes than the
PL110 supports natively)?

The particular case you're referring has been already discussed several
times, and the bottom line here is that it's not PL111 compatible (there
are more changes than just the mux) and will need separate "compatible"
value and some tweaks in the driver (in the places currently doing
CONFIG_ARCH_VERSATILE).

Now, if it was PL111 with an external, independent muxer, the pads
description would still hold its value (PL111's R would still be wired
up at a particular pad etc.) and the display pipeline drivers would have
to handle the case.

Err.  Somehow, I don't think you understand the hardware you're messing
with there.  Remember, I wrote support all the support code for the
PL11x and supporting this.

Yes, the Versatile PL110 has one difference: it has the IENB and CNTL
registers swapped compared to the conventional PL110 devices.  This can
be handled via an appropriate compatible property.  The hardware cursor
registers are also omitted, but that's irrelevant as we don't use that.

Other than that, it's a standard PL110.  Connected to its outputs is a
PLD.  Inside the PLD is a mux controlled via the SYS_CLCD register.

As far as the CLD outputs are concerned, they are standard.  The PLD on
their outputs routes the CLD bits to the 8-bit red, green and blue
channels according to the configuration of SYS_CLCD to achieve the
various colour formats which the CLCD does not natively provide for.

So, it /is/ a PL110 with an independent external muxer.

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