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

[Petr Belyaev <upcfrost@gmail.com>]

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.

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.

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.

Restore the PP_TABLE_V1 condition. With it back the failed messages
disappear entirely and both the boot modeset and the monitor wake are
immediate.

Fixes: 0138610c1413 ("drm/amd/pm/smu7: Fix SMU7 voltage dependency on display clock")
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5678
Cc: stable@vger.kernel.org
Signed-off-by: Petr Belyaev <upcfrost@gmail.com>
---
 drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_hwmgr.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_hwmgr.c b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_hwmgr.c
index 6529a91..aadf6d5 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_hwmgr.c
+++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_hwmgr.c
@@ -3189,7 +3189,11 @@ static int smu7_upload_dpm_level_enable_mask(struct pp_hwmgr *hwmgr)
 {
 	struct smu7_hwmgr *data = (struct smu7_hwmgr *)(hwmgr->backend);
 
-	smu7_apply_minimum_dce_voltage_request(hwmgr);
+	/* CI SMC firmware does not implement PPSMC_MSG_VddC_Request, and each
+	 * attempt costs a full SMC response timeout.
+	 */
+	if (hwmgr->pp_table_version == PP_TABLE_V1)
+		smu7_apply_minimum_dce_voltage_request(hwmgr);
 
 	if (!data->sclk_dpm_key_disabled) {
 		if (data->dpm_level_enable_mask.sclk_dpm_enable_mask)
-- 
2.54.0
:wqa