[PATCH v2] drm/amdgpu: expose amdgpu_sensors on pre-powerplay chips

[Tom St Denis]

On 14/02/17 12:16 PM, Tom St Denis wrote:
> On 14/02/17 12:01 PM, Samuel Pitoiset wrote:
>> No worries. I thought that check was enough. Anyway, writing code
>> without the hardware should be avoided. :)
>>
>> Can you try the thing suggested by Alex? Because I will need to fix up
>> the DRM ioctl codepath as well.
>
> Sure, I'm building a module with a amdgpu_dpm check near the top of the
> debugfs read function.

It seems returning an error code causes it to do "bad things" on read

[root at kaveri linux]# git diff
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 80821b4..d63c443 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -3198,6 +3198,9 @@ static ssize_t amdgpu_debugfs_sensor_read(struct 
file *f, char __user *buf,
         if (size & 3 || *pos & 0x3)
                 return -EINVAL;

+       if (amdgpu_dpm == 0)
+               return -EINVAL;
+
         /* convert offset to sensor number */
         idx = *pos >> 2;

That's what I applied on top of Samuel's three patches.

With DPM enabled it works fine obviously, with it disabled the entire 
system hangs.  I think probably because the VFS spins trying to read but 
never finishes...

Any ideas?

Tom