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Message-ID: <CAAVeFuJFCQdRuuJ=WQAL65MMoWzPj03evGiXmfQh=2K7+i5Gdg@mail.gmail.com> Date: Tue, 22 Jul 2014 13:21:38 +0900 From: Alexandre Courbot <gnurou@...il.com> To: Alexandre Courbot <acourbot@...dia.com> Cc: David Airlie <airlied@...ux.ie>, Ben Skeggs <bskeggs@...hat.com>, David Herrmann <dh.herrmann@...il.com>, "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org> Subject: Re: [PATCH RESEND] drm/ttm: expose CPU address of DMA-allocated pages DRM maintainers, could I have a comment about this patch? A bunch of Nouveau changes depend on it. Thanks, Alex. On Tue, Jul 15, 2014 at 11:10 AM, Alexandre Courbot <acourbot@...dia.com> wrote: > Pages allocated using the DMA API have a coherent memory mapping. Make > this mapping visible to drivers so they can decide to use it instead of > creating their own redundant one. > > This is not a mere optimization: for instance, on ARM it is illegal to > have several memory mappings to the same memory with different protection. > The mapping provided by dma_alloc_coherent() and exposed by this patch is > guaranteed to be safe, but subsequent mappings performed by drivers are > not. Thus drivers using the DMA page allocator should use this mapping > instead of creating their own. > > Signed-off-by: Alexandre Courbot <acourbot@...dia.com> > --- > This patch was previously part of a series but I figured it would make more > sense to send it separately. It is to be used by Nouveau (and hopefully > other drivers) on ARM. > > drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 2 ++ > drivers/gpu/drm/ttm/ttm_tt.c | 6 +++++- > include/drm/ttm/ttm_bo_driver.h | 2 ++ > 3 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c > index fb8259f69839..0301fac5badd 100644 > --- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c > +++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c > @@ -847,6 +847,7 @@ static int ttm_dma_pool_get_pages(struct dma_pool *pool, > if (count) { > d_page = list_first_entry(&pool->free_list, struct dma_page, page_list); > ttm->pages[index] = d_page->p; > + ttm_dma->cpu_address[index] = d_page->vaddr; > ttm_dma->dma_address[index] = d_page->dma; > list_move_tail(&d_page->page_list, &ttm_dma->pages_list); > r = 0; > @@ -978,6 +979,7 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev) > INIT_LIST_HEAD(&ttm_dma->pages_list); > for (i = 0; i < ttm->num_pages; i++) { > ttm->pages[i] = NULL; > + ttm_dma->cpu_address[i] = 0; > ttm_dma->dma_address[i] = 0; > } > > diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c > index 75f319090043..341594ede596 100644 > --- a/drivers/gpu/drm/ttm/ttm_tt.c > +++ b/drivers/gpu/drm/ttm/ttm_tt.c > @@ -58,6 +58,8 @@ static void ttm_dma_tt_alloc_page_directory(struct ttm_dma_tt *ttm) > ttm->ttm.pages = drm_calloc_large(ttm->ttm.num_pages, sizeof(void*)); > ttm->dma_address = drm_calloc_large(ttm->ttm.num_pages, > sizeof(*ttm->dma_address)); > + ttm->cpu_address = drm_calloc_large(ttm->ttm.num_pages, > + sizeof(*ttm->cpu_address)); > } > > #ifdef CONFIG_X86 > @@ -228,7 +230,7 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev, > > INIT_LIST_HEAD(&ttm_dma->pages_list); > ttm_dma_tt_alloc_page_directory(ttm_dma); > - if (!ttm->pages || !ttm_dma->dma_address) { > + if (!ttm->pages || !ttm_dma->dma_address || !ttm_dma->cpu_address) { > ttm_tt_destroy(ttm); > pr_err("Failed allocating page table\n"); > return -ENOMEM; > @@ -243,6 +245,8 @@ void ttm_dma_tt_fini(struct ttm_dma_tt *ttm_dma) > > drm_free_large(ttm->pages); > ttm->pages = NULL; > + drm_free_large(ttm_dma->cpu_address); > + ttm_dma->cpu_address = NULL; > drm_free_large(ttm_dma->dma_address); > ttm_dma->dma_address = NULL; > } > diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h > index 202f0a7171e8..1d9f0f1ff52d 100644 > --- a/include/drm/ttm/ttm_bo_driver.h > +++ b/include/drm/ttm/ttm_bo_driver.h > @@ -133,6 +133,7 @@ struct ttm_tt { > * struct ttm_dma_tt > * > * @ttm: Base ttm_tt struct. > + * @cpu_address: The CPU address of the pages > * @dma_address: The DMA (bus) addresses of the pages > * @pages_list: used by some page allocation backend > * > @@ -142,6 +143,7 @@ struct ttm_tt { > */ > struct ttm_dma_tt { > struct ttm_tt ttm; > + void **cpu_address; > dma_addr_t *dma_address; > struct list_head pages_list; > }; > -- > 2.0.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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