From: Karol Herbst <karolherbst@gmail.com>
Date: Tue, 12 Jul 2016 19:36:08 +0000 (+0200)
Subject: drm/nouveau/volt: Don't require perfect fit
X-Git-Tag: v4.10-rc1~154^2~41^2~15
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=5e00e3263ba68bd32337063a43aa8467b27acd1d;p=linux.git

drm/nouveau/volt: Don't require perfect fit

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

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c
index 5e07bd3aaccc..ec59d58becdc 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/volt/base.c
+++ b/drivers/gpu/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;
 }