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

["Christian König" <christian.koenig@amd.com>]

Am 16.02.22 um 14:55 schrieb Somalapuram, Amaranath:
>
> 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 ?

I think your original idea to just always set the full list sounds 
better to me.

As I said before I think the best approach is to parse the application 
input into a full list inside the kernel first and then replace 
everything in just one go.

Clearing the list of registers to dump can then easily be done with just 
echo > file

Regards,
Christian.

>
> 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;
>>>>>>>