Hi
Am 11.06.24 um 10:23 schrieb Peng Fan:
Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
Hi
Am 11.06.24 um 03:00 schrieb Peng Fan:
Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
Hi
Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
From: Peng Fan <peng.fan@xxxxxxx>
If 'info->screen_buffer' locates in vmalloc address space,
virt_to_page will not be able to get correct results. With
CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64,
there is dump below:
Which graphics driver triggers this bug?
It is NXP i.MX95 DPU driver which is still in NXP downstream repo.
Which DRM memory manager does that driver use?
DRM_GEM_DMA_DRIVER_OPS
So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't
you allocate from one of these dma_alloc_() calls at [1] ? How does the
drivers end up with vmalloc'd fbdev memory? Specifically in the light of
the docs at [2].
[1]
https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146
[2]
https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124
Best regards
Thomas
I'm asking because if the driver allocates BOs via vmalloc(), should it really
use fbdev-dma?
We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0,
fbdev emulation could be disabled.
Thanks
Peng
Best regards
Thomas
Thanks,
Peng.
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB
36809 (AG Nuernberg)
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
