[Nouveau] [PATCH v5 15/20] volt: Don't require perfect fit

[Karol Herbst]

If we calculate the voltage in the table right, we get all kinds of values,
which never fit the hardware steps, so we use the closest higher value the
hardware can do.

v3: Simplify the implementation.
v5: Initialize best_err with volt->max_uv.

Signed-off-by: Karol Herbst <karolherbst at gmail.com>
Reviewed-by: Martin Peres <martin.peres at free.fr>
---
 drm/nouveau/nvkm/subdev/volt/base.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drm/nouveau/nvkm/subdev/volt/base.c b/drm/nouveau/nvkm/subdev/volt/base.c
index 5e07bd3..ec59d58 100644
--- a/drm/nouveau/nvkm/subdev/volt/base.c
+++ b/drm/nouveau/nvkm/subdev/volt/base.c
@@ -51,18 +51,30 @@ static int
 nvkm_volt_set(struct nvkm_volt *volt, u32 uv)
 {
 	struct nvkm_subdev *subdev = &volt->subdev;
-	int i, ret = -EINVAL;
+	int i, ret = -EINVAL, best_err = volt->max_uv, best = -1;
 
 	if (volt->func->volt_set)
 		return volt->func->volt_set(volt, uv);
 
 	for (i = 0; i < volt->vid_nr; i++) {
-		if (volt->vid[i].uv == uv) {
-			ret = volt->func->vid_set(volt, volt->vid[i].vid);
-			nvkm_debug(subdev, "set %duv: %d\n", uv, ret);
+		int err = volt->vid[i].uv - uv;
+		if (err < 0 || err > best_err)
+			continue;
+
+		best_err = err;
+		best = i;
+		if (best_err == 0)
 			break;
-		}
 	}
+
+	if (best == -1) {
+		nvkm_error(subdev, "couldn't set %iuv\n", uv);
+		return ret;
+	}
+
+	ret = volt->func->vid_set(volt, volt->vid[best].vid);
+	nvkm_debug(subdev, "set req %duv to %duv: %d\n", uv,
+		   volt->vid[best].uv, ret);
 	return ret;
 }
 
-- 
2.9.2