[Nouveau] [PATCH 16/19] clk: respect voltage limits in nvkm_cstate_prog with cstate = -1

[Karol Herbst]

we should never allow to select a cstate which current voltage (depending on
the temperature) is higher than

1. the max volt entries in the voltage map table
2. what tha gpu actually can volt to

this resolves most of the remaining volting errors on fermi and newer

Signed-off-by: Karol Herbst <nouveau at karolherbst.de>
---
 drm/nouveau/nvkm/subdev/clk/base.c | 54 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/drm/nouveau/nvkm/subdev/clk/base.c b/drm/nouveau/nvkm/subdev/clk/base.c
index 7998840..9658f6d 100644
--- a/drm/nouveau/nvkm/subdev/clk/base.c
+++ b/drm/nouveau/nvkm/subdev/clk/base.c
@@ -75,6 +75,57 @@ nvkm_clk_adjust(struct nvkm_clk *clk, bool adjust,
 /******************************************************************************
  * C-States
  *****************************************************************************/
+static bool
+nvkm_cstate_valid(struct nvkm_clk *clk, struct nvkm_cstate *cstate, u32 max_volt, int temp)
+{
+	struct nvkm_volt *volt = clk->subdev.device->volt;
+	int voltage;
+
+	if (!volt)
+		return true;
+
+	voltage = nvkm_volt_map(volt, cstate->voltage, temp);
+	if (voltage < 0)
+		return false;
+	return voltage <= min(max_volt, volt->max_uv) &&
+	       voltage >= volt->min_uv;
+}
+
+static struct nvkm_cstate *
+nvkm_cstate_find_best(struct nvkm_clk *clk, struct nvkm_pstate *pstate)
+{
+	struct nvkm_device *device = clk->subdev.device;
+	struct nvkm_therm *therm = device->therm;
+	struct nvkm_volt *volt = device->volt;
+	struct nvkm_cstate *cstate;
+	int temp = 0, max_volt;
+
+	if (!volt)
+		return list_entry(pstate->list.prev, typeof(*cstate), head);
+
+	if (therm) {
+		/* ignore error code */
+		temp = max(0, nvkm_therm_temp_get(therm));
+	}
+
+	max_volt = volt->max_uv;
+	if (volt->max0_vid != 0xff)
+		max_volt = min(max_volt,
+			       nvkm_volt_map(volt, volt->max0_vid, temp));
+	if (volt->max1_vid != 0xff)
+		max_volt = min(max_volt,
+			       nvkm_volt_map(volt, volt->max1_vid, temp));
+
+	for (cstate = list_entry(pstate->list.prev, typeof(*cstate), head);
+	     &cstate->head != &pstate->list;
+	     cstate = list_entry(cstate->head.prev, typeof(*cstate), head)) {
+		if (nvkm_cstate_valid(clk, cstate, max_volt, temp))
+			break;
+	}
+
+	return cstate;
+}
+
 static int
 nvkm_cstate_prog(struct nvkm_clk *clk, struct nvkm_pstate *pstate, int cstatei)
 {
@@ -87,8 +138,7 @@ nvkm_cstate_prog(struct nvkm_clk *clk, struct nvkm_pstate *pstate, int cstatei)
 
 	if (!list_empty(&pstate->list)) {
 		if (cstatei == -1)
-			cstate = list_entry(pstate->list.prev, typeof(*cstate),
-					    head);
+			cstate = nvkm_cstate_find_best(clk, pstate);
 		else {
 			list_for_each_entry(cstate, &pstate->list, head) {
 				if (cstate->cstate == cstatei)
-- 
2.7.3