Re: [PATCH] drm/amdgpu: fix modprobe failure of the 2nd GPU when GDDR6 training enabled

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Am 08.01.20 um 15:49 schrieb Alex Deucher:
On Wed, Jan 8, 2020 at 7:52 AM Christian König <christian.koenig@xxxxxxx> wrote:
Am 08.01.20 um 13:36 schrieb Tianci Yin:
From: "Tianci.Yin" <tianci.yin@xxxxxxx>

[why]
In dual GPUs scenario, stolen_size is assigned to zero on the 2nd GPU,
then the bottom region of VRAM was allocated as GTT, unfortunately
a small region of bottom VRAM was encroached by UMC firmware during
GDDR6 BIST training, this cause pagefault.
What I'm missing here is why is the stolen size zero on the 2nd GPU?

Maybe we need to read the stolen size after posting the GPU instead?
There is no stolen memory on secondary GPUs because there is no pre-OS
console using that memory.

Ah! Yeah that makes sense.

But in this case I would say we should change the patch like the following:

adev->gmc.stolen_size = min(adev->gmc.stolen_size, AMDGPU_STOLEN_VGA_DEFAULT_SIZE);

And in amdgpu_ttm_late_init():

/* Can't free the stolen VGA memory when it might be used for memory training again. */
if (!adev->fw_vram_usage.mem_train_support)
    amdgpu_bo_free_kernel(....


Regards,
Christian.



Alex

Regards,
Christian.

[how]
Forcing stolen_size to 3MB, then the bottom region of VRAM was
allocated as stolen memory, GTT corruption avoid.
The stolen memory of the 2nd GPU will be free in late_init phase,
no memory wasted.

Change-Id: Icd0ad7de41333282949bb1e3e676c6c307ddd081
Signed-off-by: Tianci.Yin <tianci.yin@xxxxxxx>
---
   drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h |  6 ++++++
   drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c  | 21 +++++++++++++++++++++
   2 files changed, 27 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
index c91dd602d5f1..440b793316df 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
@@ -60,6 +60,11 @@
    */
   #define AMDGPU_GMC_FAULT_TIMEOUT    5000ULL

+/*
+ * Default stolen memory size, 1024 * 768 * 4
+ */
+#define AMDGPU_STOLEN_VGA_DEFAULT_SIZE       0x300000
+
   struct firmware;

   /*
@@ -192,6 +197,7 @@ struct amdgpu_gmc {
       uint32_t                srbm_soft_reset;
       bool                    prt_warning;
       uint64_t                stolen_size;
+     bool                    stolen_temp_reserved;
       /* apertures */
       u64                     shared_aperture_start;
       u64                     shared_aperture_end;
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
index 7dc8c068c62a..0c96b67d6ca7 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
@@ -566,6 +566,11 @@ static int gmc_v10_0_late_init(void *handle)
       struct amdgpu_device *adev = (struct amdgpu_device *)handle;
       int r;

+     if (adev->gmc.stolen_temp_reserved) {
+             amdgpu_bo_late_init(adev);
+             adev->gmc.stolen_temp_reserved = false;
+     }
+
       r = amdgpu_gmc_allocate_vm_inv_eng(adev);
       if (r)
               return r;
@@ -756,6 +761,22 @@ static int gmc_v10_0_sw_init(void *handle)
               return r;

       adev->gmc.stolen_size = gmc_v10_0_get_vbios_fb_size(adev);
+     /*
+      * In dual GPUs scenario, stolen_size is assigned to zero on the 2nd GPU,
+      * then the bottom region of VRAM was allocated as GTT, unfortunately
+      * a small region of bottom VRAM was encroached by UMC firmware during
+      * GDDR6 BIST training, this cause pagefault.
+      * The page fault can be fixed by forcing stolen_size to 3MB, then the bottom
+      * region of VRAM was allocated as stolen memory, GTT corruption avoid.
+      * The stolen memory of the 2nd GPU will be free in late_init phase,
+      * no memory wasted.
+      */
+     if (adev->fw_vram_usage.mem_train_support &&
+             adev->gmc.stolen_size == 0) {
+             adev->gmc.stolen_size = AMDGPU_STOLEN_VGA_DEFAULT_SIZE;
+             adev->gmc.stolen_temp_reserved = true;
+     } else
+             adev->gmc.stolen_temp_reserved = false;

       /* Memory manager */
       r = amdgpu_bo_init(adev);
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