linux-kernel - [PATCH] drm/msm: stop abusing dma

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Message-Id: <20190630124735.27786-1-robdclark@gmail.com>
Date:   Sun, 30 Jun 2019 05:47:22 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Rob Clark <robdclark@...omium.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/msm: stop abusing dma_map/unmap for cache

From: Rob Clark <robdclark@...omium.org>

Recently splats like this started showing up:

   WARNING: CPU: 4 PID: 251 at drivers/iommu/dma-iommu.c:451 __iommu_dma_unmap+0xb8/0xc0
   Modules linked in: ath10k_snoc ath10k_core fuse msm ath mac80211 uvcvideo cfg80211 videobuf2_vmalloc videobuf2_memops vide
   CPU: 4 PID: 251 Comm: kworker/u16:4 Tainted: G        W         5.2.0-rc5-next-20190619+ #2317
   Hardware name: LENOVO 81JL/LNVNB161216, BIOS 9UCN23WW(V1.06) 10/25/2018
   Workqueue: msm msm_gem_free_work [msm]
   pstate: 80c00005 (Nzcv daif +PAN +UAO)
   pc : __iommu_dma_unmap+0xb8/0xc0
   lr : __iommu_dma_unmap+0x54/0xc0
   sp : ffff0000119abce0
   x29: ffff0000119abce0 x28: 0000000000000000
   x27: ffff8001f9946648 x26: ffff8001ec271068
   x25: 0000000000000000 x24: ffff8001ea3580a8
   x23: ffff8001f95ba010 x22: ffff80018e83ba88
   x21: ffff8001e548f000 x20: fffffffffffff000
   x19: 0000000000001000 x18: 00000000c00001fe
   x17: 0000000000000000 x16: 0000000000000000
   x15: ffff000015b70068 x14: 0000000000000005
   x13: 0003142cc1be1768 x12: 0000000000000001
   x11: ffff8001f6de9100 x10: 0000000000000009
   x9 : ffff000015b78000 x8 : 0000000000000000
   x7 : 0000000000000001 x6 : fffffffffffff000
   x5 : 0000000000000fff x4 : ffff00001065dbc8
   x3 : 000000000000000d x2 : 0000000000001000
   x1 : fffffffffffff000 x0 : 0000000000000000
   Call trace:
    __iommu_dma_unmap+0xb8/0xc0
    iommu_dma_unmap_sg+0x98/0xb8
    put_pages+0x5c/0xf0 [msm]
    msm_gem_free_work+0x10c/0x150 [msm]
    process_one_work+0x1e0/0x330
    worker_thread+0x40/0x438
    kthread+0x12c/0x130
    ret_from_fork+0x10/0x18
   ---[ end trace afc0dc5ab81a06bf ]---

Not quite sure what triggered that, but we really shouldn't be abusing
dma_{map,unmap}_sg() for cache maint.

Signed-off-by: Rob Clark <robdclark@...omium.org>
Cc: Stephen Boyd <sboyd@...nel.org>
---
 drivers/gpu/drm/msm/msm_gem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index d31d9f927887..3b84cbdcafa3 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -108,7 +108,7 @@ static struct page **get_pages(struct drm_gem_object *obj)
 		 * 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,
+			dma_sync_sg_for_device(dev->dev, msm_obj->sgt->sgl,
 					msm_obj->sgt->nents, DMA_BIDIRECTIONAL);
 	}
 
@@ -138,7 +138,7 @@ static void put_pages(struct drm_gem_object *obj)
 			 * 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,
+				dma_sync_sg_for_cpu(obj->dev->dev, msm_obj->sgt->sgl,
 					     msm_obj->sgt->nents,
 					     DMA_BIDIRECTIONAL);
 
-- 
2.20.1