RE: [PATCH] drm/fbdev-dma: fix getting smem_start

[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

> 
> 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)