drm/nouveau/volt: Make use of cvb coefficients

I'm quite sure that those coefficients are real close, because while
testing the biggest error compared to nvidia was around -1.5% (biggest
error with right coefficients is 12.5mV / 600mV = 2%).

These coefficients were REed by modifing the voltage map entries and by
calculating the set voltage back until I was able to forecast which voltage
nvidia sets for a given voltage map entry.

With these formulars I am able to precisely predict at which exact
temperature Nvidia down- or upvolts due to a changed therm reading.

That's why I am quite sure these are right, or at least really really
close.

v4: Use better coefficients and speedo.
v5: Add error message when speedo is missing.

Signed-off-by: Karol Herbst <karolherbst@gmail.com>
Reviewed-by: Martin Peres <martin.peres@free.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c
index 771419ff8338410e405f8c612f9f43172c7ee7ff..90d234231eedeac26c7044cddbd32ffe91cf0ef7 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c
@@ -110,13 +110,47 @@ nvkm_volt_map(struct nvkm_volt *volt, u8 id, u8 temp)
 
        vmap = nvbios_vmap_entry_parse(bios, id, &ver, &len, &info);
        if (vmap) {
+               s64 result;
+
+               if (volt->speedo < 0)
+                       return volt->speedo;
+
+               if (ver == 0x10 || (ver == 0x20 && info.mode == 0)) {
+                       result  =  (s64)info.arg[0] / 10;
+                       result += ((s64)info.arg[1] * volt->speedo) / 10;
+                       result += ((s64)info.arg[2] * volt->speedo * volt->speedo) / 100000;
+               } else if (ver == 0x20) {
+                       switch (info.mode) {
+                       /* 0x0 handled above! */
+                       case 0x1:
+                               result =  ((s64)info.arg[0] * 15625) >> 18;
+                               result += ((s64)info.arg[1] * volt->speedo * 15625) >> 18;
+                               result += ((s64)info.arg[2] * temp * 15625) >> 10;
+                               result += ((s64)info.arg[3] * volt->speedo * temp * 15625) >> 18;
+                               result += ((s64)info.arg[4] * volt->speedo * volt->speedo * 15625) >> 30;
+                               result += ((s64)info.arg[5] * temp * temp * 15625) >> 18;
+                               break;
+                       case 0x3:
+                               result = (info.min + info.max) / 2;
+                               break;
+                       case 0x2:
+                       default:
+                               result = info.min;
+                               break;
+                       }
+               } else {
+                       return -ENODEV;
+               }
+
+               result = min(max(result, (s64)info.min), (s64)info.max);
+
                if (info.link != 0xff) {
                        int ret = nvkm_volt_map(volt, info.link, temp);
                        if (ret < 0)
                                return ret;
-                       info.min += ret;
+                       result += ret;
                }
-               return info.min;
+               return result;
        }
 
        return id ? id * 10000 : -ENODEV;