Re: [PATCH v12 1/2] drm/amdgpu: add debugfs for reset registers list

["Somalapuram, Amaranath" <asomalap@xxxxxxx>]

On 2/22/2022 9:08 PM, Christian König wrote:
> Am 22.02.22 um 16:34 schrieb Somalapuram Amaranath:
> > List of register populated for dump collection during the GPU reset.
> >
> > Signed-off-by: Somalapuram Amaranath <Amaranath.Somalapuram@xxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  4 +
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 83 +++++++++++++++++++++
> >   2 files changed, 87 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > index b85b67a88a3d..6e35f2c4c869 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                             num_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..0cc80aa1b5ec 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> > @@ -1609,6 +1609,87 @@ 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, ret, len = 0;
> > +
> > +    if (*pos)
> > +        return 0;
> > +
> > +    ret = down_read_killable(&adev->reset_sem);
> > +    if (ret)
> > +        return ret;
> > +
> > +    for (i = 0; i < adev->num_regs; i++) {
> > +        sprintf(reg_offset, "0x%x\n", adev->reset_dump_reg_list[i]);
> > +        up_read(&adev->reset_sem);
> > +        ret = copy_to_user(buf + len, reg_offset, strlen(reg_offset));
> > +        if (ret)
> > +            return -EFAULT;
> > +
> > +        len += strlen(reg_offset);
> > +        ret = down_read_killable(&adev->reset_sem);
> > +        if (ret)
> > +            return ret;
> > +    }
> > +
> > +    up_read(&adev->reset_sem);
> > +    if (ret)
> > +        return ret;
>
> That if and return now looks superfluous.
>
> > +
> > +    *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[12];
> > +    uint32_t *tmp;
> > +    int ret, i = 0, len = 0;
> > +
> > +    do {
> > +        memset(reg_offset, 0, 12);
> > +        if (copy_from_user(reg_offset, buf + len,
> > +                    min(11, ((int)size-len)))) {
> > +            ret = -EFAULT;
> > +            goto error_free;
> > +        }
> > +
> > +        tmp = krealloc_array(tmp, i + 1, sizeof(uint32_t), GFP_KERNEL);
> > +        if (sscanf(reg_offset, "%X %n", &tmp[i], &ret) != 1)
>
> Does this also work when we write the registers separated with 
> newlines into the debugfs file?
Yes. tested with with both.
> Regards,
> Christian.
>
> > +            goto error_free;
> > +
> > +        len += ret;
> > +        i++;
> > +    } while (len < size);
> > +
> > +    ret = down_write_killable(&adev->reset_sem);
> > +    if (ret)
> > +        goto error_free;
> > +
> > +    swap(adev->reset_dump_reg_list, tmp);
> > +    adev->num_regs = i;
> > +    up_write(&adev->reset_sem);
> > +    ret = size;
> > +
> > +error_free:
> > +    kfree(tmp);
> > +    return ret;
> > +}
> > +
> > +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 +1753,8 @@ 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;