[PATCH v4 2/4] drm/shmem-helper: Switch to vmf_insert_pfn
Thomas Zimmermann
tzimmermann at suse.de
Thu Jul 22 18:22:43 UTC 2021
Hi,
I'm not knowledgeable enougth to give this a full review. If you can
just answer my questions, fell free to add an
Acked-by: Thomas Zimmermann <tzimmermann at suse.de>
to the patch. :)
Am 13.07.21 um 22:51 schrieb Daniel Vetter:
> We want to stop gup, which isn't the case if we use vmf_insert_page
What is gup?
> and VM_MIXEDMAP, because that does not set pte_special.
>
> v2: With this shmem gem helpers now definitely need CONFIG_MMU (0day)
>
> v3: add more depends on MMU. For usb drivers this is a bit awkward,
> but really it's correct: To be able to provide a contig mapping of
> buffers to userspace on !MMU platforms we'd need to use the cma
> helpers for these drivers on those platforms. As-is this wont work.
>
> Also not exactly sure why vm_insert_page doesn't go boom, because that
> definitely wont fly in practice since the pages are non-contig to
> begin with.
>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Maxime Ripard <mripard at kernel.org>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: David Airlie <airlied at linux.ie>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> ---
> drivers/gpu/drm/Kconfig | 2 +-
> drivers/gpu/drm/drm_gem_shmem_helper.c | 4 ++--
> drivers/gpu/drm/gud/Kconfig | 2 +-
> drivers/gpu/drm/tiny/Kconfig | 4 ++--
> drivers/gpu/drm/udl/Kconfig | 1 +
> 5 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 0d372354c2d0..314eefa39892 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -211,7 +211,7 @@ config DRM_KMS_CMA_HELPER
>
> config DRM_GEM_SHMEM_HELPER
> bool
> - depends on DRM
> + depends on DRM && MMU
> help
> Choose this if you need the GEM shmem helper functions
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index d5e6d4568f99..296ab1b7c07f 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -542,7 +542,7 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
> } else {
> page = shmem->pages[page_offset];
>
> - ret = vmf_insert_page(vma, vmf->address, page);
> + ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
> }
>
> mutex_unlock(&shmem->pages_lock);
> @@ -612,7 +612,7 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
> return ret;
> }
>
> - vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
> + vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND;
> vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> if (shmem->map_wc)
> vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
> diff --git a/drivers/gpu/drm/gud/Kconfig b/drivers/gpu/drm/gud/Kconfig
> index 1c8601bf4d91..9c1e61f9eec3 100644
> --- a/drivers/gpu/drm/gud/Kconfig
> +++ b/drivers/gpu/drm/gud/Kconfig
> @@ -2,7 +2,7 @@
>
> config DRM_GUD
> tristate "GUD USB Display"
> - depends on DRM && USB
> + depends on DRM && USB && MMU
> select LZ4_COMPRESS
> select DRM_KMS_HELPER
> select DRM_GEM_SHMEM_HELPER
I'm a kconfig noob, so this is rather a question than a review comment:
If DRM_GEM_SHMEM_HELPER already depends on MMU, this select will fail on
non-MMU platforms? Why does the driver also depend on MMU? Simply to
make the item disappear in menuconfig?
Best regards
Thomas
> diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> index 5593128eeff9..c11fb5be7d09 100644
> --- a/drivers/gpu/drm/tiny/Kconfig
> +++ b/drivers/gpu/drm/tiny/Kconfig
> @@ -44,7 +44,7 @@ config DRM_CIRRUS_QEMU
>
> config DRM_GM12U320
> tristate "GM12U320 driver for USB projectors"
> - depends on DRM && USB
> + depends on DRM && USB && MMU
> select DRM_KMS_HELPER
> select DRM_GEM_SHMEM_HELPER
> help
> @@ -53,7 +53,7 @@ config DRM_GM12U320
>
> config DRM_SIMPLEDRM
> tristate "Simple framebuffer driver"
> - depends on DRM
> + depends on DRM && MMU
> select DRM_GEM_SHMEM_HELPER
> select DRM_KMS_HELPER
> help
> diff --git a/drivers/gpu/drm/udl/Kconfig b/drivers/gpu/drm/udl/Kconfig
> index 1f497d8f1ae5..c744175c6992 100644
> --- a/drivers/gpu/drm/udl/Kconfig
> +++ b/drivers/gpu/drm/udl/Kconfig
> @@ -4,6 +4,7 @@ config DRM_UDL
> depends on DRM
> depends on USB
> depends on USB_ARCH_HAS_HCD
> + depends on MMU
> select DRM_GEM_SHMEM_HELPER
> select DRM_KMS_HELPER
> help
>
--
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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