Hi
Am 14.05.20 um 14:40 schrieb Daniel Vetter:
> On Wed, May 13, 2020 at 05:03:11PM +0200, Thomas Zimmermann wrote:
>> SHMEM-buffer backing storage is allocated from system memory; which is
>> typically cachable. Currently, only virtio uses cachable mappings; udl
>> uses its own vmap/mmap implementation for cachable mappings. Other
>> drivers default to writecombine mappings.
>
> I'm pretty sure this breaks all these drivers. quick grep on a few
> functions says this is used by lima, panfrost, v3d. And they definitely
> need uncached/wc stuff afaiui. Or I'm completely missing something?
OK, I better get some testing for this code. :D
> -Daniel
>
>>
>> Use cached mappings by default. The exception is pages imported via
>> dma-buf. DMA memory is usually not cached.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>> ---
>> drivers/gpu/drm/drm_gem_shmem_helper.c | 6 ++++--
>> drivers/gpu/drm/virtio/virtgpu_object.c | 1 -
>> include/drm/drm_gem_shmem_helper.h | 4 ++--
>> 3 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
>> index df31e5782eed1..1ce90325dfa31 100644
>> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
>> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
>> @@ -259,7 +259,7 @@ static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
>> } else {
>> pgprot_t prot = PAGE_KERNEL;
>>
>> - if (!shmem->map_cached)
>> + if (shmem->map_wc)
>> prot = pgprot_writecombine(prot);
>> shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
>> VM_MAP, prot);
>> @@ -546,7 +546,7 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>>
>> vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
>> vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
>> - if (!shmem->map_cached)
>> + if (shmem->map_wc)
>> vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
>> vma->vm_ops = &drm_gem_shmem_vm_ops;
>>
>> @@ -664,6 +664,8 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
>> if (IS_ERR(shmem))
>> return ERR_CAST(shmem);
>>
>> + shmem->map_wc = false; /* dma-buf mappings use writecombine */
>> +
>> shmem->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
>> if (!shmem->pages) {
>> ret = -ENOMEM;
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
>> index 6ccbd01cd888c..80ba6b2b61668 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_object.c
>> +++ b/drivers/gpu/drm/virtio/virtgpu_object.c
>> @@ -132,7 +132,6 @@ struct drm_gem_object *virtio_gpu_create_object(struct drm_device *dev,
>>
>> dshmem = &shmem->base.base;
>> dshmem->base.funcs = &virtio_gpu_shmem_funcs;
>> - dshmem->map_cached = true;
>> return &dshmem->base;
>> }
>>
>> diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
>> index 294b2931c4cc0..a5bc082a77c48 100644
>> --- a/include/drm/drm_gem_shmem_helper.h
>> +++ b/include/drm/drm_gem_shmem_helper.h
>> @@ -98,9 +98,9 @@ struct drm_gem_shmem_object {
>> unsigned int vmap_use_count;
>>
>> /**
>> - * @map_cached: map object cached (instead of using writecombine).
>> + * @map_wc: map object using writecombine (instead of cached).
>> */
>> - bool map_cached;
>> + bool map_wc;
>> };
>>
>> #define to_drm_gem_shmem_obj(obj) \
>> --
>> 2.26.2
>>
>
--
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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