dma_map_sg() expects a DMA domain. However, the drm devices
have been traditionally using unmanaged iommu domain which
is non-dma type. Using dma mapping APIs with that domain is bad.
Replace dma_map_sg() calls with dma_sync_sg_for_device{|cpu}()
to do the cache maintenance.
Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
Suggested-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
---
Tested on an MTP sdm845:
https://github.com/vivekgautam1/linux/tree/v4.19/sdm845-mtp-display-working
drivers/gpu/drm/msm/msm_gem.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 00c795ced02c..d7a7af610803 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -81,6 +81,8 @@ static struct page **get_pages(struct drm_gem_object *obj)
struct drm_device *dev = obj->dev;
struct page **p;
int npages = obj->size >> PAGE_SHIFT;
+ struct scatterlist *s;
+ int i;
if (use_pages(obj))
p = drm_gem_get_pages(obj);
@@ -107,9 +109,19 @@ static struct page **get_pages(struct drm_gem_object *obj)
/* For non-cached buffers, ensure the new pages are clean
* because display controller, GPU, etc. are not coherent:
*/
- if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
- dma_map_sg(dev->dev, msm_obj->sgt->sgl,
- msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
+ if (msm_obj->flags & (MSM_BO_WC | MSM_BO_UNCACHED)) {
+ /*
+ * Fake up the SG table so that dma_sync_sg_*()
+ * can be used to flush the pages associated with it.
+ */
+ for_each_sg(msm_obj->sgt->sgl, s,
+ msm_obj->sgt->nents, i)
+ sg_dma_address(s) = sg_phys(s);
+
+ dma_sync_sg_for_device(dev->dev, msm_obj->sgt->sgl,
+ msm_obj->sgt->nents,
+ DMA_TO_DEVICE);
+ }
}
return msm_obj->pages;
@@ -137,10 +149,11 @@ static void put_pages(struct drm_gem_object *obj)
* pages are clean because display controller,
* GPU, etc. are not coherent:
*/
- if (msm_obj->flags & (MSM_BO_WC|MSM_BO_UNCACHED))
- dma_unmap_sg(obj->dev->dev, msm_obj->sgt->sgl,
- msm_obj->sgt->nents,
- DMA_BIDIRECTIONAL);
+ if (msm_obj->flags & (MSM_BO_WC | MSM_BO_UNCACHED))
+ dma_sync_sg_for_cpu(obj->dev->dev,
+ msm_obj->sgt->sgl,
+ msm_obj->sgt->nents,
+ DMA_FROM_DEVICE);
sg_free_table(msm_obj->sgt);
kfree(msm_obj->sgt);
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation
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