Re: [PATCH v6 1/2] drm/amdgpu: add debugfs for reset registers list

["Lazar, Lijo" <lijo.lazar@amd.com>]

On 2/16/2022 4:04 PM, Somalapuram, Amaranath wrote:
> 
> On 2/16/2022 3:45 PM, Lazar, Lijo wrote:
>>
>>
>> On 2/16/2022 3:19 PM, Somalapuram Amaranath wrote:
>>> List of register populated for dump collection during the GPU reset.
>>>
>>> Signed-off-by: Somalapuram Amaranath <Amaranath.Somalapuram@amd.com>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  5 ++
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 95 +++++++++++++++++++++
>>>   2 files changed, 100 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index b85b67a88a3d..57965316873b 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -1097,6 +1097,11 @@ 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;
>>> +    struct mutex            reset_dump_mutex;
>>>   };
>>>     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..faf985c7cb93 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> @@ -1609,6 +1609,98 @@ 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[11];
>>> +    int i, r, len = 0;
>>> +
>>> +    if (*pos)
>>> +        return 0;
>>> +
>>> +    if (adev->n_regs == 0)
>>> +        return 0;
>>> +
>>> +    for (i = 0; i < adev->n_regs; i++) {
>>> +        sprintf(reg_offset, "0x%x ", adev->reset_dump_reg_list[i]);
>>> +        r = copy_to_user(buf + len, reg_offset, strlen(reg_offset));
>>> +
>>> +        if (r)
>>> +            return -EFAULT;
>>> +
>>> +        len += strlen(reg_offset);
>>> +    }
>>> +
>>> +    r = copy_to_user(buf + len, "\n", 1);
>>> +
>>> +    if (r)
>>> +        return -EFAULT;
>>> +
>>> +    len++;
>>> +    *pos += len;
>>> +
>>> +    return len;
>>> +}
>>> +
>>> +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, reg_temp[11];
>>> +    static int alloc_count;
>>
>> This being static what happens when it is called on a second device?
>>
>> Thanks,
>> Lijo
>>
> I tried to avoid adding to adev. It wont work for multiple devices.

Hmm.This is not friendly for single device also. Some one could just 
parse a text file of reg offsets and do
	sudo echo offset > file

This will overwrite whatever is there. Instead you may define a syntax like	
	sudo echo 0x000 > file =>  Clears all
	sudo echo offset > file => Append to the existing set.

Taking all offsets in one go may not be needed.

Thanks,
Lijo

>>> +    int ret, i = 0, len = 0;
>>> +
>>> +    do {
>>> +        reg_offset = reg_temp;
>>> +        memset(reg_offset,  0, 11);
>>> +        ret = copy_from_user(reg_offset, buf + len, min(11, 
>>> ((int)size-len)));
>>> +
>>> +        if (ret)
>>> +            goto failed;
>>> +
>>> +        reg = strsep(&reg_offset, " ");
>>> +
>>> +        if (alloc_count <= i) {
>>> +            adev->reset_dump_reg_list =  krealloc_array(
>>> +                            adev->reset_dump_reg_list, 1,
>>> +                            sizeof(uint32_t), GFP_KERNEL);
>>> +            alloc_count++;
>>> +        }
>>> +
>>> +        ret = kstrtouint(reg, 16, &adev->reset_dump_reg_list[i]);
>>> +
>>> +        if (ret)
>>> +            goto failed;
>>> +
>>> +        len += strlen(reg) + 1;
>>> +        i++;
>>> +
>>> +    } while (len < size);
>>> +
>>> +    adev->n_regs = i;
>>> +
>>> +    return size;
>>> +
>>> +failed:
>>> +    mutex_lock(&adev->reset_dump_mutex);
>>> +    kfree(adev->reset_dump_reg_list);
>>> +    adev->reset_dump_reg_list = NULL;
>>> +    alloc_count = 0;
>>> +    adev->n_regs = 0;
>>> +    mutex_unlock(&adev->reset_dump_mutex);
>>> +    return -EFAULT;
>>> +}
>>> +
>>> +
>>> +
>>> +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;
>>> @@ -1618,6 +1710,7 @@ int amdgpu_debugfs_init(struct amdgpu_device 
>>> *adev)
>>>       if (!debugfs_initialized())
>>>           return 0;
>>>   +    mutex_init(&adev->reset_dump_mutex);
>>>       ent = debugfs_create_file("amdgpu_preempt_ib", 0600, root, adev,
>>>                     &fops_ib_preempt);
>>>       if (IS_ERR(ent)) {
>>> @@ -1672,6 +1765,8 @@ 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;
>>>