# [v3,16/29] volt: don't require perfect fit

Submitted by Karol Herbst on April 7, 2016, 9:24 p.m.

## Details

Message ID 1460064259-1243-17-git-send-email-nouveau@karolherbst.de New show "Volting/Clocking improvements for Fermi and newer" ( rev: 3 ) in Nouveau

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## Commit Message

Karol Herbst April 7, 2016, 9:24 p.m.
```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

Signed-off-by: Karol Herbst <nouveau@karolherbst.de>
---
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 a133b9c..552fecd 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 = 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;
}

```