Re: [PATCH] drm/amdgpu/sdma5.2: soft reset sdma blocks before setup and start sdma

[Deucher, Alexander]

[AMD Official Use Only - Internal Distribution Only]

Acked-by: Alex Deucher <alexander.deuc...@amd.com>
________________________________
From: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> on behalf of Xiaomeng Hou 
<xiaomeng....@amd.com>
Sent: Thursday, December 10, 2020 7:59 AM
To: amd-gfx@lists.freedesktop.org <amd-gfx@lists.freedesktop.org>
Cc: Gao, Likun <likun....@amd.com>; Huang, Ray <ray.hu...@amd.com>; Hou, 
Xiaomeng (Matthew) <xiaomeng....@amd.com>
Subject: [PATCH] drm/amdgpu/sdma5.2: soft reset sdma blocks before setup and 
start sdma

Without doing the soft reset, register mmSDMA0_GFX_RB_WPTR's value could not be
reset to 0 when sdma block resumes. That would cause the ring buffer's read and
write pointers not equal and ring test fail. So add the soft reset step.

Signed-off-by: Xiaomeng Hou <xiaomeng....@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c | 39 +++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c 
b/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c
index 39e17aae655f..5acc1e589672 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c
@@ -807,6 +807,37 @@ static int sdma_v5_2_load_microcode(struct amdgpu_device 
*adev)
         return 0;
 }

+static int sdma_v5_2_soft_reset(void *handle)
+{
+       struct amdgpu_device *adev = (struct amdgpu_device *)handle;
+       u32 grbm_soft_reset = 0;
+       u32 tmp;
+       int i;
+
+       for (i = 0; i < adev->sdma.num_instances; i++) {
+               grbm_soft_reset = REG_SET_FIELD(grbm_soft_reset,
+                                               GRBM_SOFT_RESET, 
SOFT_RESET_SDMA0,
+                                               1);
+               grbm_soft_reset <<= i;
+
+               tmp = RREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET);
+               tmp |= grbm_soft_reset;
+               DRM_DEBUG("GRBM_SOFT_RESET=0x%08X\n", tmp);
+               WREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET, tmp);
+               tmp = RREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET);
+
+               udelay(50);
+
+               tmp &= ~grbm_soft_reset;
+               WREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET, tmp);
+               tmp = RREG32_SOC15(GC, 0, mmGRBM_SOFT_RESET);
+
+               udelay(50);
+       }
+
+       return 0;
+}
+
 /**
  * sdma_v5_2_start - setup and start the async dma engines
  *
@@ -838,6 +869,7 @@ static int sdma_v5_2_start(struct amdgpu_device *adev)
                         msleep(1000);
         }

+       sdma_v5_2_soft_reset(adev);
         /* unhalt the MEs */
         sdma_v5_2_enable(adev, true);
         /* enable sdma ring preemption */
@@ -1366,13 +1398,6 @@ static int sdma_v5_2_wait_for_idle(void *handle)
         return -ETIMEDOUT;
 }

-static int sdma_v5_2_soft_reset(void *handle)
-{
-       /* todo */
-
-       return 0;
-}
-
 static int sdma_v5_2_ring_preempt_ib(struct amdgpu_ring *ring)
 {
         int i, r = 0;
--
2.17.1

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