drm/nouveau/clk: make therm and volt devices optional

Allow the clock subsystem to operate even if voltage and thermal devices
are not set for the device (for people with watercooling! ;))
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/subdev/clock/base.c

@@ -90,17 +90,21 @@ nouveau_cstate_prog(struct nouveau_clock *clk,
 		cstate = &pstate->base;
 	}
 
+	if (ptherm) {
 		ret = nouveau_therm_cstate(ptherm, pstate->fanspeed, +1);
 		if (ret && ret != -ENODEV) {
 			nv_error(clk, "failed to raise fan speed: %d\n", ret);
 			return ret;
 		}
+	}
 
+	if (volt) {
 		ret = volt->set_id(volt, cstate->voltage, +1);
 		if (ret && ret != -ENODEV) {
 			nv_error(clk, "failed to raise voltage: %d\n", ret);
 			return ret;
 		}
+	}
 
 	ret = clk->calc(clk, cstate);
 	if (ret == 0) {
@@ -108,13 +112,17 @@ nouveau_cstate_prog(struct nouveau_clock *clk,
 		clk->tidy(clk);
 	}
 
+	if (volt) {
 		ret = volt->set_id(volt, cstate->voltage, -1);
 		if (ret && ret != -ENODEV)
 			nv_error(clk, "failed to lower voltage: %d\n", ret);
+	}
 
+	if (ptherm) {
 		ret = nouveau_therm_cstate(ptherm, pstate->fanspeed, -1);
 		if (ret && ret != -ENODEV)
 			nv_error(clk, "failed to lower fan speed: %d\n", ret);
+	}
 
 	return 0;
 }