[PATCH 1/6] drm/fbdev-generic: Always use shadow buffering

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann at suse.de> writes:

Hello Thomas,

> Remove all codepaths that implement fbdev output directly on GEM
> buffers. Always allocate a shadow buffer in system memory and set
> up deferred I/O for mmap.
>
> The fbdev code that operated directly on GEM buffers was used by
> drivers based on GEM DMA helpers. Those drivers have been migrated
> to use fbdev-dma, a dedicated fbdev emulation for DMA memory. All
> remaining users of fbdev-generic require shadow buffering.
>
> Memory management of the remaining callers uses TTM, GEM SHMEM
> helpers or a variant of GEM DMA helpers that is incompatible with
> fbdev-dma. Therefore remove the unused codepaths from fbdev-generic
> and simplify the code.
>
> Using a shadow buffer with deferred I/O is probably the best case
> for most remaining callers. Some of the TTM-based drivers might
> benefit from a dedicated fbdev emulation that operates directly on
> the driver's video memory.
>

But it's questionable if that would be useful due the limited ammount of
video memory that most of the devices using TTM-based drivers have, right?

> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> ---

It's much cleaner indeed to have fbdev-dma separated from fbdev-generic.

Reviewed-by: Javier Martinez Canillas <javierm at redhat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat