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

["Somalapuram, Amaranath" <asomalap@amd.com>]

On 2/16/2022 6:47 PM, Lazar, Lijo wrote:
>
>
> On 2/16/2022 4:39 PM, Somalapuram, Amaranath wrote:
>>
>> On 2/16/2022 4:13 PM, Lazar, Lijo wrote:
>>>
>>>
>>> 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
>>>
>>
>> 0x000 can be offset for some registers !
>
> It's indeed a valid register called MM_INDEX register. The register 
> doesn't have any meaning in standalone.
>
>> This is application responsibly; any wrong data should clear the list.
>> Application can read back the list for confomation.
>>
>
> It needs to be done by user app anyway. This is more about how 
> convenient the interface is. Probably you could switch to a user 
> standpoint and try to add some 20-30 registers to the list. Then steps 
> needed to add a revised list.
>

For clear we can send text “clear”
On next write should we replace or append ? (I think with "clear" append 
is better option)

Christian which is better ?

Regards,
S.Amarnath
> Thanks,
> Lijo
>
>> Regards,
>> S.Amarnath
>>>>>> +    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;
>>>>>>