[PATCH v2] drm/amdgpu/gfx11: need acquire mutex before access CP_VMID_RESET v2

[Zhang, Hawking]

[AMD Official Use Only - General]

Better to use dev_err or DRM_ERROR. Apart from that, the patch is

Reviewed-by: Hawking Zhang <Hawking.Zhang at amd.com>

Regards,
Hawking

-----Original Message-----
From: Xiao, Jack <Jack.Xiao at amd.com>
Sent: Thursday, December 21, 2023 18:29
To: amd-gfx at lists.freedesktop.org; Deucher, Alexander <Alexander.Deucher at amd.com>; Zhang, Hawking <Hawking.Zhang at amd.com>
Cc: Xiao, Jack <Jack.Xiao at amd.com>
Subject: [PATCH v2] drm/amdgpu/gfx11: need acquire mutex before access CP_VMID_RESET v2

It's required to take the gfx mutex before access to CP_VMID_RESET, for there is a race condition with CP firmware to write the register.

v2: add extra code to ensure the mutex releasing is successful.

Signed-off-by: Jack Xiao <Jack.Xiao at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c | 48 +++++++++++++++++++++++++-
 1 file changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
index bdcf96df69e6..44f5b3135931 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
@@ -4474,11 +4474,43 @@ static int gfx_v11_0_wait_for_idle(void *handle)
        return -ETIMEDOUT;
 }

+static int gfx_v11_0_request_gfx_index_mutex(struct amdgpu_device *adev,
+                                            int req)
+{
+       u32 i, tmp, val;
+
+       for (i = 0; i < adev->usec_timeout; i++) {
+               /* Request with MeId=2, PipeId=0 */
+               tmp = REG_SET_FIELD(0, CP_GFX_INDEX_MUTEX, REQUEST, req);
+               tmp = REG_SET_FIELD(tmp, CP_GFX_INDEX_MUTEX, CLIENTID, 4);
+               WREG32_SOC15(GC, 0, regCP_GFX_INDEX_MUTEX, tmp);
+
+               val = RREG32_SOC15(GC, 0, regCP_GFX_INDEX_MUTEX);
+               if (req) {
+                       if (val == tmp)
+                               break;
+               } else {
+                       tmp = REG_SET_FIELD(tmp, CP_GFX_INDEX_MUTEX,
+                                           REQUEST, 1);
+
+                       /* unlocked or locked by firmware */
+                       if (val != tmp)
+                               break;
+               }
+               udelay(1);
+       }
+
+       if (i >= adev->usec_timeout)
+               return -EINVAL;
+
+       return 0;
+}
+
 static int gfx_v11_0_soft_reset(void *handle)  {
        u32 grbm_soft_reset = 0;
        u32 tmp;
-       int i, j, k;
+       int r, i, j, k;
        struct amdgpu_device *adev = (struct amdgpu_device *)handle;

        tmp = RREG32_SOC15(GC, 0, regCP_INT_CNTL); @@ -4518,6 +4550,13 @@ static int gfx_v11_0_soft_reset(void *handle)
                }
        }

+       /* Try to acquire the gfx mutex before access to CP_VMID_RESET */
+       r = gfx_v11_0_request_gfx_index_mutex(adev, 1);
+       if (r) {
+               printk("Failed to acquire the gfx mutex during soft reset\n");
+               return r;
+       }
+
        WREG32_SOC15(GC, 0, regCP_VMID_RESET, 0xfffffffe);

        // Read CP_VMID_RESET register three times.
@@ -4526,6 +4565,13 @@ static int gfx_v11_0_soft_reset(void *handle)
        RREG32_SOC15(GC, 0, regCP_VMID_RESET);
        RREG32_SOC15(GC, 0, regCP_VMID_RESET);

+       /* release the gfx mutex */
+       r = gfx_v11_0_request_gfx_index_mutex(adev, 0);
+       if (r) {
+               printk("Failed to release the gfx mutex during soft reset\n");
+               return r;
+       }
+
        for (i = 0; i < adev->usec_timeout; i++) {
                if (!RREG32_SOC15(GC, 0, regCP_HQD_ACTIVE) &&
                    !RREG32_SOC15(GC, 0, regCP_GFX_HQD_ACTIVE))
--
2.41.0