[PATCH] drm/amd/pm: Fix that RPM cannot be obtained for specific GPU

[huangyizhi]

The current mechanism for obtaining RPM is to read tach_period from
the register, and then calculate the RPM together with the frequency.
But we found that on specific GPUs, such as RX 550 and RX 560D,
tach_period always reads as 0 and smu7_fan_ctrl_get_fan_speed_rpm
will returns -EINVAL.

To solve this problem, when reading tach_period as 0, we try
to estimate the current RPM using the percentage of current pwm, the
maximum and minimum RPM.

Signed-off-by: huangyizhi <huangyi...@hnu.edu.cn>
---
 .../drm/amd/pm/powerplay/hwmgr/smu7_thermal.c | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_thermal.c 
b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_thermal.c
index a6c3610db23e..307dd87d6882 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_thermal.c
+++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu7_thermal.c
@@ -81,6 +81,11 @@ int smu7_fan_ctrl_get_fan_speed_rpm(struct pp_hwmgr *hwmgr, 
uint32_t *speed)
 {
        uint32_t tach_period;
        uint32_t crystal_clock_freq;
+       uint32_t duty100;
+       uint32_t duty;
+       uint32_t speed_percent;
+       uint64_t tmp64;
+
 
        if (hwmgr->thermal_controller.fanInfo.bNoFan ||
            !hwmgr->thermal_controller.fanInfo.ucTachometerPulsesPerRevolution)
@@ -89,13 +94,28 @@ int smu7_fan_ctrl_get_fan_speed_rpm(struct pp_hwmgr *hwmgr, 
uint32_t *speed)
        tach_period = PHM_READ_VFPF_INDIRECT_FIELD(hwmgr->device, 
CGS_IND_REG__SMC,
                        CG_TACH_STATUS, TACH_PERIOD);
 
-       if (tach_period == 0)
-               return -EINVAL;
+       if (tach_period == 0) {
 
-       crystal_clock_freq = amdgpu_asic_get_xclk((struct amdgpu_device 
*)hwmgr->adev);
+               duty100 = PHM_READ_VFPF_INDIRECT_FIELD(hwmgr->device, 
CGS_IND_REG__SMC,
+                               CG_FDO_CTRL1, FMAX_DUTY100);
+               duty = PHM_READ_VFPF_INDIRECT_FIELD(hwmgr->device, 
CGS_IND_REG__SMC,
+                               CG_THERMAL_STATUS, FDO_PWM_DUTY);
 
-       *speed = 60 * crystal_clock_freq * 10000 / tach_period;
+               if (duty100 == 0)
+                       return -EINVAL;
 
+               tmp64 = (uint64_t)duty * 100;
+               do_div(tmp64, duty100);
+               speed_percent = MIN((uint32_t)tmp64, 100);
+
+               *speed = speed_percent * 
(hwmgr->thermal_controller.fanInfo.ulMaxRPM
+                       - hwmgr->thermal_controller.fanInfo.ulMinRPM) / 100;
+       } else {
+
+               crystal_clock_freq = amdgpu_asic_get_xclk((struct amdgpu_device 
*)hwmgr->adev);
+
+               *speed = 60 * crystal_clock_freq * 10000 / tach_period;
+       }
        return 0;
 }
 
-- 
2.30.0