Re: [PATCH v3 1/2] drm/amdgpu: add debugfs for reset registers list

[Somalapuram, Amaranath]

On 2/14/2022 2:59 PM, Christian König wrote:


Am 14.02.22 um 10:16 schrieb Somalapuram Amaranath:
List of register populated for dump collection during the GPU reset.

Signed-off-by: Somalapuram Amaranath <amaranath.somalapu...@amd.com>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  4 ++
  drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 80 +++++++++++++++++++++
  2 files changed, 84 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index b85b67a88a3d..2e8c2318276d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1097,6 +1097,10 @@ struct amdgpu_device {
        struct amdgpu_reset_control     *reset_cntl;
      uint32_t ip_versions[HW_ID_MAX][HWIP_MAX_INSTANCE];
+
+    /* reset dump register */
+    uint32_t            *reset_dump_reg_list;
+    int                             n_regs;
  };
    static inline struct amdgpu_device *drm_to_adev(struct drm_device 
*ddev)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index 164d6a9e9fbb..6d49bed5b761 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -1609,6 +1609,84 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_ib_preempt, NULL,
  DEFINE_DEBUGFS_ATTRIBUTE(fops_sclk_set, NULL,
              amdgpu_debugfs_sclk_set, "%llu\n");
  +static ssize_t amdgpu_reset_dump_register_list_read(struct file *f,
+                char __user *buf, size_t size, loff_t *pos)
+{
+    struct amdgpu_device *adev = (struct amdgpu_device 
*)file_inode(f)->i_private;
+    char *reg_offset;
+    int i, r, len;
+
+    if (adev->n_regs == 0)
+        return 0;
+
+    reg_offset = kmalloc((adev->n_regs * 11) + 1, GFP_KERNEL);
+    memset(reg_offset,  0, (adev->n_regs * 11) + 1);
+
+    for (i = 0; i < adev->n_regs; i++)
+        sprintf(reg_offset + strlen(reg_offset), "0x%x ", 
adev->reset_dump_reg_list[i]);
+
+    sprintf(reg_offset + strlen(reg_offset), "\n");
+    len = strlen(reg_offset);
+
+    if (*pos >= len)
+        return 0;
+
+    r = copy_to_user(buf, reg_offset, len);

Maybe better copy that to userspace one register at a time. This is 
not performance critical in any way.

Same for the write function.

Regards,
Christian.

I tried to push all list of register in one go, so that the list can be 
overwritten/updated (every write makes new list)
if we add one register at a time from user-space the design will change 
to appending the list and cant be edited or updated, it should be OK ?
and don't see much use of **_read api (as we can see the list in trace) 
i will remove it (debugfs interface will change from string to uint32_t )!?

Regards,
S.Amarnath
+    *pos += len - r;
+    kfree(reg_offset);
+
+    return len - r;
+}
+
+static ssize_t amdgpu_reset_dump_register_list_write(struct file *f,
+            const char __user *buf, size_t size, loff_t *pos)
+{
+    struct amdgpu_device *adev = (struct amdgpu_device 
*)file_inode(f)->i_private;
+    char *reg_offset, *reg;
+    int ret, i = 0;
+
+    reg_offset = kmalloc(size, GFP_KERNEL);
+    memset(reg_offset,  0, size);
+    ret = copy_from_user(reg_offset, buf, size);
+
+    if (ret)
+        return -EFAULT;
+
+    if (adev->n_regs > 0) {
+        adev->n_regs = 0;
+        kfree(adev->reset_dump_reg_list);
+        adev->reset_dump_reg_list = NULL;
+    }
+
+    while ((reg = strsep(&reg_offset, " ")) != NULL) {
+        adev->reset_dump_reg_list =  krealloc_array(
+                        adev->reset_dump_reg_list, 1,
+                        sizeof(uint32_t), GFP_KERNEL);
+        ret  = kstrtouint(reg, 16, &adev->reset_dump_reg_list[i]);
+
+        if (ret) {
+            kfree(adev->reset_dump_reg_list);
+            kfree(reg_offset);
+            adev->reset_dump_reg_list = NULL;
+            return -EINVAL;
+        }
+
+        i++;
+    }
+
+    adev->n_regs = i;
+    kfree(reg_offset);
+
+    return size;
+}
+
+static const struct file_operations amdgpu_reset_dump_register_list = {
+    .owner = THIS_MODULE,
+    .read = amdgpu_reset_dump_register_list_read,
+    .write = amdgpu_reset_dump_register_list_write,
+    .llseek = default_llseek
+};
+
  int amdgpu_debugfs_init(struct amdgpu_device *adev)
  {
      struct dentry *root = adev_to_drm(adev)->primary->debugfs_root;
@@ -1672,6 +1750,8 @@ int amdgpu_debugfs_init(struct amdgpu_device 
*adev)
                  &amdgpu_debugfs_test_ib_fops);
      debugfs_create_file("amdgpu_vm_info", 0444, root, adev,
                  &amdgpu_debugfs_vm_info_fops);
+    debugfs_create_file("amdgpu_reset_dump_register_list", 0644, 
root, adev,
+                &amdgpu_reset_dump_register_list);
        adev->debugfs_vbios_blob.data = adev->bios;
      adev->debugfs_vbios_blob.size = adev->bios_size;