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

[Thomas Zimmermann]

Hi

Am 04.09.24 um 08:43 schrieb Alexander Stein:
> 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 at 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 at 18000000, compatible id shared-dma-pool
>> OF: reserved mem: 0x18000000..0x187fffff (8192 KiB) nomap non-reusable
>> vram at 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]

IIRC vram needs to be located in HighMem for the code to work. What is 
the difference between these zones?

Best regards
Thomas

>
> 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

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
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