Re: [PATCH] drm/amd/pm/smu7: Don't send VddC_Request on CI

["Timur Kristóf" <timur.kristof@gmail.com>]

On Monday, August 24, 2026 4:47:14 PM Central European Summer Time Petr 
Belyaev wrote:
> smu7_upload_dpm_level_enable_mask() calls
> smu7_apply_minimum_dce_voltage_request() unconditionally, which sends
> PPSMC_MSG_VddC_Request to the SMC. CI SMC firmware does not implement
> that message: it is only defined in smu7_ppsmc.h, tonga_ppsmc.h and
> fiji_ppsmc.h, and there is no CI equivalent. The SMC therefore never
> writes SMC_RESP, PHM_WAIT_FIELD_UNEQUAL() spins until it gives up, and
> every call burns the full ~1.9s response timeout.

Hi,

I'm sorry but this is wrong.
I added the VDDC request specifically to solve an issue with a Bonaire GPU.
That system will boot into a black screen without requesting a high enough 
voltage for the display engine. This patch would regress that.

> 
> Nothing downstream notices, because ci_send_msg_to_smc() returns 0
> regardless of the outcome. The only effects are the delay and
> 
>   amdgpu: failed to send message 15f ret is 0
> 
> in dmesg. On a Radeon R7 260X (BONAIRE, 1002:6658) this is 40 messages
> per boot: 32 during the boot-time modeset, which becomes ~59s of blank
> screen, and 8 more on every DPMS wake, adding ~15s before the display
> comes back.

How do you reproduce this issue, and on which kernel version?
I've tested this patch on two different Bonaire chips and a Hawaii chip, and 
haven't seen this error message. In fact I am running an R9 390X right now and 
I don't see this error message in my logs.

> 
> Commit 0138610c1413 ("drm/amd/pm/smu7: Fix SMU7 voltage dependency on
> display clock") extended this feature to CI, which the previous
> implementation had deliberately excluded -- the old call site was
> guarded by pp_table_version == PP_TABLE_V1 with an adjacent comment
> reading "TO DO for v0 iceland and Ci". That commit was verified on a
> Radeon R9 M380, which is VI, so the CI path went untested.

The CI path definitely did not go untested.
R9 M380 is Bonaire (it's in an old iMac).
You can see all the details here:
https://gitlab.freedesktop.org/drm/amd/-/work_items/3425#note_3338643

Best regards,
Timur