[PATCH v2 4/4] drm/udl: Remove struct udl_gem_object and functions

[Thomas Zimmermann]

Hi Noralf

Am 06.11.19 um 12:48 schrieb Noralf Trønnes:
> 
> 
> Den 06.11.2019 11.47, skrev Thomas Zimmermann:
>> Simply removes all the obsolete GEM code from udl. No functional
>> changes.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>> ---
>>  drivers/gpu/drm/udl/Makefile     |   2 +-
>>  drivers/gpu/drm/udl/udl_dmabuf.c | 254 -------------------------------
>>  drivers/gpu/drm/udl/udl_drv.h    |  29 ----
>>  drivers/gpu/drm/udl/udl_gem.c    | 206 -------------------------
>>  4 files changed, 1 insertion(+), 490 deletions(-)
>>  delete mode 100644 drivers/gpu/drm/udl/udl_dmabuf.c
>>
> 
> <snip>
> 
>> -int udl_gem_vmap(struct udl_gem_object *obj)
>> -{
>> -	int page_count = obj->base.size / PAGE_SIZE;
>> -	int ret;
>> -
>> -	if (obj->base.import_attach) {
>> -		obj->vmapping = dma_buf_vmap(obj->base.import_attach->dmabuf);
>> -		if (!obj->vmapping)
>> -			return -ENOMEM;
>> -		return 0;
>> -	}
>> -
>> -	ret = udl_gem_get_pages(obj);
>> -	if (ret)
>> -		return ret;
>> -
>> -	obj->vmapping = vmap(obj->pages, page_count, 0, PAGE_KERNEL);
> 
> This differs from the shmem helper vmap:
> 
> 	shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
> 			    VM_MAP, pgprot_writecombine(PAGE_KERNEL));
> 
> Boris added the WC in be7d9f05c53e:
> 
>  drm/gem_shmem: Use a writecombine mapping for ->vaddr
> 
>  Right now, the BO is mapped as a cached region when ->vmap() is called
>  and the underlying object is not a dmabuf.
>  Doing that makes cache management a bit more complicated (you'd need
>  to call dma_map/unmap_sg() on the ->sgt field everytime the BO is about
>  to be passed to the GPU/CPU), so let's map the BO with writecombine
>  attributes instead (as done in most drivers).
> 
> I don't know what the implications of this are, just pointing out a
> difference.

After some testing, I added an udl vmap function that enables caching on
the pages. I think I see a performance improvement for full-screen updates.

Best regards
Thomas

> 
> Noralf.
> 
>> -	if (!obj->vmapping)
>> -		return -ENOMEM;
>> -	return 0;
>> -}
> 
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-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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