drm/vmwgfx: Use the dma scatter-gather iterator to get dma addresses

Use struct sg_dma_page_iter in favour struct of sg_page_iter, which fairly
recently was declared useless for obtaining dma addresses.

With a struct sg_dma_page_iter we can't call sg_page_iter_page() so
when the page is needed, use the same page lookup mechanism as for the
non-sg dma modes instead of calling sg_dma_page_iter.

Note, the fixes tag doesn't really point to a commit introducing a
failure / regression, but rather to a commit that implemented a simple
workaround for this problem.

Cc: Jason Gunthorpe <jgg@mellanox.com>
Fixes: d901b2760dc6 ("lib/scatterlist: Provide a DMA page iterator")
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 96983c4..366dcfc 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -296,7 +296,7 @@ struct vmw_sg_table {
 struct vmw_piter {
        struct page **pages;
        const dma_addr_t *addrs;
-       struct sg_page_iter iter;
+       struct sg_dma_page_iter iter;
        unsigned long i;
        unsigned long num_pages;
        bool (*next)(struct vmw_piter *);

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
index a3357ff..a6ea75b 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
@@ -266,7 +266,9 @@ static bool __vmw_piter_non_sg_next(struct vmw_piter *viter)
 
 static bool __vmw_piter_sg_next(struct vmw_piter *viter)
 {
-       return __sg_page_iter_next(&viter->iter);
+       bool ret = __vmw_piter_non_sg_next(viter);
+
+       return __sg_page_iter_dma_next(&viter->iter) && ret;
 }
 
 
@@ -284,12 +286,6 @@ static struct page *__vmw_piter_non_sg_page(struct vmw_piter *viter)
        return viter->pages[viter->i];
 }
 
-static struct page *__vmw_piter_sg_page(struct vmw_piter *viter)
-{
-       return sg_page_iter_page(&viter->iter);
-}
-
-
 /**
  * Helper functions to return the DMA address of the current page.
  *
@@ -311,13 +307,7 @@ static dma_addr_t __vmw_piter_dma_addr(struct vmw_piter *viter)
 
 static dma_addr_t __vmw_piter_sg_addr(struct vmw_piter *viter)
 {
-       /*
-        * FIXME: This driver wrongly mixes DMA and CPU SG list iteration and
-        * needs revision. See
-        * https://lore.kernel.org/lkml/20190104223531.GA1705@ziepe.ca/
-        */
-       return sg_page_iter_dma_address(
-               container_of(&viter->iter, struct sg_dma_page_iter, base));
+       return sg_page_iter_dma_address(&viter->iter);
 }
 
 
@@ -336,26 +326,23 @@ void vmw_piter_start(struct vmw_piter *viter, const struct vmw_sg_table *vsgt,
 {
        viter->i = p_offset - 1;
        viter->num_pages = vsgt->num_pages;
+       viter->page = &__vmw_piter_non_sg_page;
+       viter->pages = vsgt->pages;
        switch (vsgt->mode) {
        case vmw_dma_phys:
                viter->next = &__vmw_piter_non_sg_next;
                viter->dma_address = &__vmw_piter_phys_addr;
-               viter->page = &__vmw_piter_non_sg_page;
-               viter->pages = vsgt->pages;
                break;
        case vmw_dma_alloc_coherent:
                viter->next = &__vmw_piter_non_sg_next;
                viter->dma_address = &__vmw_piter_dma_addr;
-               viter->page = &__vmw_piter_non_sg_page;
                viter->addrs = vsgt->addrs;
-               viter->pages = vsgt->pages;
                break;
        case vmw_dma_map_populate:
        case vmw_dma_map_bind:
                viter->next = &__vmw_piter_sg_next;
                viter->dma_address = &__vmw_piter_sg_addr;
-               viter->page = &__vmw_piter_sg_page;
-               __sg_page_iter_start(&viter->iter, vsgt->sgt->sgl,
+               __sg_page_iter_start(&viter->iter.base, vsgt->sgt->sgl,
                                     vsgt->sgt->orig_nents, p_offset);
                break;
        default: