Re: [PATCH v2 1/2] drm/amdgpu: add debugfs for reset registers list

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Am 11.02.22 um 14:15 schrieb Somalapuram, Amaranath:
> On 2/11/2022 5:22 PM, Christian König wrote:
> > Am 11.02.22 um 12:47 schrieb Somalapuram Amaranath:
> > > List of register to be populated for dump collection during the GPU 
> > > reset.
> > >
> > > Signed-off-by: Somalapuram Amaranath <Amaranath.Somalapuram@xxxxxxx>
> > > ---
> > >   drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  5 ++
> > >   drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 61 
> > > +++++++++++++++++++++
> > >   2 files changed, 66 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > > index b85b67a88a3d..b90349b86918 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> > > @@ -813,6 +813,7 @@ struct amd_powerplay {
> > >     #define AMDGPU_RESET_MAGIC_NUM 64
> > >   #define AMDGPU_MAX_DF_PERFMONS 4
> > > +#define AMDGPU_RESET_DUMP_REGS_MAX     128
> > >   struct amdgpu_device {
> > >       struct device            *dev;
> > >       struct pci_dev            *pdev;
> > > @@ -1097,6 +1098,10 @@ 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[AMDGPU_RESET_DUMP_REGS_MAX];
> >
> > Using an xarray or just dynamic allocation with krealloc_array would 
> > probably be better.
> >
> > Regards,
> > Christian.
> I can use krealloc_array,
> Then in the second patch i need to use kmalloc (or hard-code values) 
> for this: uint32_t reg_value[AMDGPU_RESET_DUMP_REGS_MAX];
> We actually tried to avoid  dynamic allocation during reset (second 
> patch).

It's correct that you can't allocate any memory during reset, but that's 
also not necessary since you just need to trace one register at a time 
and that uses the trace ring buffer.

> Also AMDGPU_RESET_DUMP_REGS_MAX getting used in trace function.

Exactly that's what I'm trying to avoid here. Big traces have caused us 
quite a bunch of problems already :)

Regards,
Christian.

> Regards,
> S.Amarnath
> > > +    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..fb99f3d657a4 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> > > @@ -1609,6 +1609,65 @@ 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;
> > > +
> > > +    reg_offset = kmalloc(2048, GFP_KERNEL);
> > > +    memset(reg_offset,  0, 2048);
> > > +    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);
> > > +    *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;
> > > +
> > > +    while ((reg = strsep(&reg_offset, " ")) != NULL) {
> > > +        ret  = kstrtouint(reg, 16, &adev->reset_dump_reg_list[i]);
> > > +        if (ret)
> > > +            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 +1731,8 @@ 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;