drm/nouveau/therm/fan/tach: default to 2 pulses per revolution

I spent some time this weekend trying to find in the vbios the number of
pulses per revolutions in the vbios but couldn't find it. It would seem
all my cards have 2 pulses per revolution so let's stick to that until
further notice.

Thermal table's id 0x48 may indicate this information but it would seem
that changing the value results in the blob power or clock gating the
RPM counter... We should ask NVIDIA about that, should be trivial-enough
for them to answer.

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

diff --git a/drivers/gpu/drm/nouveau/core/subdev/therm/nva3.c b/drivers/gpu/drm/nouveau/core/subdev/therm/nva3.c
index 3b2c4580098bafea567ebadd0cfdb972adeadf93..0478b2e3fb1de76ee34e40a56e0d6209ffff1d60 100644 (file)
--- a/drivers/gpu/drm/nouveau/core/subdev/therm/nva3.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/therm/nva3.c
@@ -36,7 +36,7 @@ nva3_therm_fan_sense(struct nouveau_therm *therm)
        u32 tach = nv_rd32(therm, 0x00e728) & 0x0000ffff;
        u32 ctrl = nv_rd32(therm, 0x00e720);
        if (ctrl & 0x00000001)
-               return tach * 60;
+               return tach * 60 / 2;
        return -ENODEV;
 }