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Re: [RFC PATCH v2] hw/display/tcx: Allow 64-bit accesses to framebuffer
From: |
Mark Cave-Ayland |
Subject: |
Re: [RFC PATCH v2] hw/display/tcx: Allow 64-bit accesses to framebuffer stippler and blitter |
Date: |
Sun, 30 Aug 2020 08:32:12 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 |
On 29/08/2020 17:45, Philippe Mathieu-Daudé wrote:
> Le sam. 29 août 2020 18:14, Michael <macallan1888@gmail.com
> <mailto:macallan1888@gmail.com>> a écrit :
>
> Hello,
>
> since I wrote the NetBSD code in question, here are my 2 cent:
>
> On Sat, 29 Aug 2020 08:41:43 -0700
> Richard Henderson <richard.henderson@linaro.org
> <mailto:richard.henderson@linaro.org>> wrote:
>
> > On 8/22/20 7:21 AM, Philippe Mathieu-Daudé wrote:
> > > The S24/TCX datasheet is listed as "Unable to locate" on [1].
>
> I don't have it either, but someone did a lot of reverse engineering
> and gave me his notes. The hardware isn't that complicated, but quite
> weird.
>
> > > However the NetBSD revision 1.32 of the driver introduced
> > > 64-bit accesses to the stippler and blitter [2]. It is safe
> > > to assume these memory regions are 64-bit accessible.
> > > QEMU implementation is 32-bit, so fill the 'impl' fields.
>
> IIRC the real hardware *requires* 64bit accesses for stipple and
> blitter operations to work. For stipples you write a 64bit word into
> STIP space, the address defines where in the framebuffer you want to
> draw, the data contain a 32bit bitmask, foreground colour and a ROP.
> BLIT space works similarly, the 64bit word contains an offset were to
> read pixels from, and how many you want to copy.
>
>
> Thanks Michael for this information!
> If you don't mind I'll amend it to the commit description so there is a
> reference for
> posterity.
>
> I'm waiting for /Andreas Gustafsson to test it then will repost.
Hi Philippe,
Thanks for coming up with this patch! Looks fine to me, just wondering if it
should
have a "Fixes: 5d971f9e67 ("memory: Revert "memory: accept mismatching sizes in
memory_region_access_valid"") tag rather than the original commit since that's
how
other bugs exposed by that commit have been tagged?
ATB,
Mark.