Re: [PATCH v3 21/43] drm/fbdev-dma: Implement damage handling and deferred I/O

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi Linus,

Am Mittwoch, 4. September 2024, 08:36:46 CEST schrieb Linus Walleij:
> On Wed, Sep 4, 2024 at 8:09 AM Alexander Stein
> <alexander.stein@ew.tq-group.com> wrote:
> 
> > Can you please check in which memory zone this VRAM is located. In my case
> > it's important CMA is located in Normal zone to trigger this problem.
> 
> dmesg says this:
> 
> Reserved memory: created DMA memory pool at 0x18000000, size 8 MiB
> OF: reserved mem: initialized node vram@18000000, compatible id shared-dma-pool
> OF: reserved mem: 0x18000000..0x187fffff (8192 KiB) nomap non-reusable
> vram@18000000
> cma: Reserved 16 MiB at 0xef000000 on node -1
> Zone ranges:
>   Normal   [mem 0x0000000080000000-0x00000000efffffff]
> Movable zone start for each node
> Early memory node ranges
>   node   0: [mem 0x0000000080000000-0x00000000efffffff]
> Initmem setup node 0 [mem 0x0000000080000000-0x00000000efffffff]
> percpu: Embedded 15 pages/cpu s39052 r0 d22388 u61440
> 
> So at the top of the normal zone at 0xef000000 as I read it.

Okay, so it is the same as for me. It seems you don't have any HighMem.
On a different model having more memory there is also HighMem available:

[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000010000000-0x000000003fffffff]
[    0.000000]   HighMem  [mem 0x0000000040000000-0x000000004fffffff]

If I explicitly configure CMA in HighMem I don't have any issues.
But the 512MiB models don't have enough memory for fixed allocation in HighMem.

I was about to send a revert myself as I didn't get any feedback yet.

Best regards,
Alexander
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