Bug 201615

Check whether azx_vs_gpu_bound gets called on your system, and see which client_id value is passed.  The flag for runtime PM for discrete GPU must be enabled (cleared) there.

Hi Takashi, 
thank you for your prompt answer. I am sorry though, you'll have be be a little more ELI5 with me - I do know how to bisect a kernel bug, but other than that I'll need some handholding to do the debugging that you need. Back over here (https://bugs.freedesktop.org/show_bug.cgi?id=106597) Lukas Wunner did a very good job leading me through the necessary steps (just to give you an idea of my level of ...competence...).

So, where would I look for azx_vs_gpu_bound? 
Should I look in both the 'vanilla' kernel and the one where I reverted your patch?

Thank you for your help!

For checking the call of azx_vs_gpu_bound(), just put a debug print like:

--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1330,6 +1330,7 @@ static void azx_vs_gpu_bound(struct pci_dev *pci,
        struct azx *chip = card->private_data;
        struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
 
+       dev_info(&pci->dev, "XXX azx_vs_gpu_bound: client_id=%d\n", client_id);
        if (client_id == VGA_SWITCHEROO_DIS)
                hda->need_eld_notify_link = 0;
        setup_vga_switcheroo_runtime_pm(chip);

... onto the original code (no revert), and reboot and check the kernel message.  I guess this print won't be triggered.

If my guess is correct, a patch below might fix the issue.  Please check it out.

Created attachment 279309 [details]
Test fix patch

Created attachment 279317 [details]
dmesg of kernel 4.19 with both patches applied

OK, seems that you were right on the first count - I'm not seeing that debug message printed in the dmesg. However, even with your proposed patch applied, I'm still getting this:

       │ File: /sys/kernel/debug/dri/1/amdgpu_pm_info
───────┼──────────────────────────────────────────────
   1   │ Clock Gating Flags Mask: 0x3fbcf
   2   │         Graphics Medium Grain Clock Gating: On
   3   │         Graphics Medium Grain memory Light Sleep: On
   4   │         Graphics Coarse Grain Clock Gating: On
   5   │         Graphics Coarse Grain memory Light Sleep: On
   6   │         Graphics Coarse Grain Tree Shader Clock Gating: Off
   7   │         Graphics Coarse Grain Tree Shader Light Sleep: Off
   8   │         Graphics Command Processor Light Sleep: On
   9   │         Graphics Run List Controller Light Sleep: On
  10   │         Graphics 3D Coarse Grain Clock Gating: Off
  11   │         Graphics 3D Coarse Grain memory Light Sleep: Off
  12   │         Memory Controller Light Sleep: On
  13   │         Memory Controller Medium Grain Clock Gating: On
  14   │         System Direct Memory Access Light Sleep: Off
  15   │         System Direct Memory Access Medium Grain Clock Gating: On
  16   │         Bus Interface Medium Grain Clock Gating: Off
  17   │         Bus Interface Light Sleep: On
  18   │         Unified Video Decoder Medium Grain Clock Gating: On
  19   │         Video Compression Engine Medium Grain Clock Gating: On
  20   │         Host Data Path Light Sleep: On
  21   │         Host Data Path Medium Grain Clock Gating: On
  22   │         Digital Right Management Medium Grain Clock Gating: Off
  23   │         Digital Right Management Light Sleep: Off
  24   │         Rom Medium Grain Clock Gating: On
  25   │         Data Fabric Medium Grain Clock Gating: Off
  26   │ 
  27   │ GFX Clocks and Power:
  28   │         0 MHz (MCLK)
  29   │         0 MHz (SCLK)
  30   │         300 MHz (PSTATE_SCLK)
  31   │         300 MHz (PSTATE_MCLK)
  32   │         900 mV (VDDGFX)
  33   │         10.57 W (average GPU)
  34   │ 
  35   │ GPU Temperature: 49 C
  36   │ GPU Load: 0 %
  37   │ 
  38   │ UVD: Disabled
  39   │ 
  40   │ VCE: Disabled

Thanks for testing.  I see the problem in my test patch.  vga_switcheroo_ready() isn't suitable there, and we should call it there unconditionally.

The revised patch is below.  Please give it a try.

Created attachment 279319 [details]
Revised test patch

OK, with the revised patch from comment 7 and your debug print from earlier applied on top of 4.20-rc1 I am now getting a kernel print:

> $ dmesg | grep -i azx
> [14.320229] snd_hda_intel 0000:01:00.1: XXX azx_vs_gpu_bound: client_id=1

Also:

File: /sys/kernel/debug/dri/1/amdgpu_pm_info
───────┼───────────────────────────────────────
   1   │ Clock Gating Flags Mask: 0x3fbcf
   2   │         Graphics Medium Grain Clock Gating: On
   3   │         Graphics Medium Grain memory Light Sleep: On
   4   │         Graphics Coarse Grain Clock Gating: On
   5   │         Graphics Coarse Grain memory Light Sleep: On
   6   │         Graphics Coarse Grain Tree Shader Clock Gating: Off
   7   │         Graphics Coarse Grain Tree Shader Light Sleep: Off
   8   │         Graphics Command Processor Light Sleep: On
   9   │         Graphics Run List Controller Light Sleep: On
  10   │         Graphics 3D Coarse Grain Clock Gating: Off
  11   │         Graphics 3D Coarse Grain memory Light Sleep: Off
  12   │         Memory Controller Light Sleep: On
  13   │         Memory Controller Medium Grain Clock Gating: On
  14   │         System Direct Memory Access Light Sleep: Off
  15   │         System Direct Memory Access Medium Grain Clock Gating: On
  16   │         Bus Interface Medium Grain Clock Gating: Off
  17   │         Bus Interface Light Sleep: On
  18   │         Unified Video Decoder Medium Grain Clock Gating: On
  19   │         Video Compression Engine Medium Grain Clock Gating: On
  20   │         Host Data Path Light Sleep: On
  21   │         Host Data Path Medium Grain Clock Gating: On
  22   │         Digital Right Management Medium Grain Clock Gating: Off
  23   │         Digital Right Management Light Sleep: Off
  24   │         Rom Medium Grain Clock Gating: On
  25   │         Data Fabric Medium Grain Clock Gating: Off
  26   │ 
  27   │ PX asic powered off

I guess that counts as a success?

Looks good, yeah.  I'm going to submit the proper patch (attached below) for review to the upstream.  Thanks!

Created attachment 279323 [details]
Fix patch (proeprly formatted)

Thank you for the quick resolution!

The fix was merged to sound git tree and will be likely included in 4.20-rc2, then backported to 4.19.y stable eventually later.