[PATCH] nouveau: use ttm populate mapping functions. (v2)

[Ruhl, Michael J]

>-----Original Message-----
>From: Ben Skeggs <skeggsb at gmail.com>
>Sent: Tuesday, July 28, 2020 4:16 PM
>To: Ruhl, Michael J <michael.j.ruhl at intel.com>
>Cc: Dave Airlie <airlied at gmail.com>; dri-devel at lists.freedesktop.org;
>bskeggs at redhat.com
>Subject: Re: [PATCH] nouveau: use ttm populate mapping functions. (v2)
>
>On Wed, 29 Jul 2020 at 02:08, Ruhl, Michael J <michael.j.ruhl at intel.com>
>wrote:
>>
>> >-----Original Message-----
>> >From: dri-devel <dri-devel-bounces at lists.freedesktop.org> On Behalf Of
>> >Dave Airlie
>> >Sent: Monday, July 27, 2020 11:26 PM
>> >To: dri-devel at lists.freedesktop.org
>> >Cc: bskeggs at redhat.com
>> >Subject: [PATCH] nouveau: use ttm populate mapping functions. (v2)
>> >
>> >From: Dave Airlie <airlied at redhat.com>
>> >
>> >Instead of rolling driver copies of them.
>> >
>> >v2: cleanup return handling (Ben)
>> >Signed-off-by: Dave Airlie <airlied at redhat.com>
>> >---
>> > drivers/gpu/drm/nouveau/nouveau_bo.c | 38 ++--------------------------
>> > 1 file changed, 2 insertions(+), 36 deletions(-)
>> >
>> >diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c
>> >b/drivers/gpu/drm/nouveau/nouveau_bo.c
>> >index 7806278dce57..6ef5085c9a91 100644
>> >--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
>> >+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
>> >@@ -1231,8 +1231,6 @@ nouveau_ttm_tt_populate(struct ttm_tt *ttm,
>> >struct ttm_operation_ctx *ctx)
>> >       struct ttm_dma_tt *ttm_dma = (void *)ttm;
>> >       struct nouveau_drm *drm;
>> >       struct device *dev;
>> >-      unsigned i;
>> >-      int r;
>> >       bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG);
>> >
>> >       if (ttm->state != tt_unpopulated)
>> >@@ -1260,31 +1258,7 @@ nouveau_ttm_tt_populate(struct ttm_tt *ttm,
>> >struct ttm_operation_ctx *ctx)
>> >               return ttm_dma_populate((void *)ttm, dev, ctx);
>> >       }
>> > #endif
>> >-
>> >-      r = ttm_pool_populate(ttm, ctx);
>> >-      if (r) {
>> >-              return r;
>> >-      }
>> >-
>> >-      for (i = 0; i < ttm->num_pages; i++) {
>> >-              dma_addr_t addr;
>> >-
>> >-              addr = dma_map_page(dev, ttm->pages[i], 0, PAGE_SIZE,
>> >-                                  DMA_BIDIRECTIONAL);
>> >-
>> >-              if (dma_mapping_error(dev, addr)) {
>> >-                      while (i--) {
>> >-                              dma_unmap_page(dev, ttm_dma-
>> >>dma_address[i],
>> >-                                             PAGE_SIZE,
>> >DMA_BIDIRECTIONAL);
>> >-                              ttm_dma->dma_address[i] = 0;
>> >-                      }
>> >-                      ttm_pool_unpopulate(ttm);
>> >-                      return -EFAULT;
>> >-              }
>> >-
>> >-              ttm_dma->dma_address[i] = addr;
>> >-      }
>> >-      return 0;
>> >+      return ttm_populate_and_map_pages(dev, ttm_dma, ctx);
>>
>> This is not a completely straight code replacement.
>>
>> ttm_populate_and_map_pages() also has code to deal with pages that are
>> contiguous (consolidates them).
>>
>> Is it possible that the nouveau HW can't handle a contiguous buffer larger
>> than PAG_SIZE?
>I think it's fine.  The function appears to consolidate the pages for
>the dma_map_page() call, but otherwise leave dma_address[] in
>PAGE_SIZE chunks, I don't believe anything else in the driver will
>care.

Ahh..  I misread it.   This is limiting the calls to dma_map_page().  Instead
of calling it for each page, just do it for the first one...

Thanks for setting me straight. 😊

Reviewed-by: Michael J. Ruhl <michael.j.ruhl at intel.com>

Mike


>Ben.
>
>>
>> Thanks,
>>
>> Mike
>>
>> > }
>> >
>> > static void
>> >@@ -1293,7 +1267,6 @@ nouveau_ttm_tt_unpopulate(struct ttm_tt *ttm)
>> >       struct ttm_dma_tt *ttm_dma = (void *)ttm;
>> >       struct nouveau_drm *drm;
>> >       struct device *dev;
>> >-      unsigned i;
>> >       bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG);
>> >
>> >       if (slave)
>> >@@ -1316,14 +1289,7 @@ nouveau_ttm_tt_unpopulate(struct ttm_tt
>*ttm)
>> >       }
>> > #endif
>> >
>> >-      for (i = 0; i < ttm->num_pages; i++) {
>> >-              if (ttm_dma->dma_address[i]) {
>> >-                      dma_unmap_page(dev, ttm_dma->dma_address[i],
>> >PAGE_SIZE,
>> >-                                     DMA_BIDIRECTIONAL);
>> >-              }
>> >-      }
>> >-
>> >-      ttm_pool_unpopulate(ttm);
>> >+      ttm_unmap_and_unpopulate_pages(dev, ttm_dma);
>> > }
>> >
>> > void
>> >--
>> >2.26.2
>> >
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