On 21/03/16 18:16, Karol Herbst wrote:
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
This is indeed the goal.
Signed-off-by: Karol Herbst <[email protected]>
---
drm/nouveau/nvkm/subdev/volt/base.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/drm/nouveau/nvkm/subdev/volt/base.c
b/drm/nouveau/nvkm/subdev/volt/base.c
index e741383..58738e3 100644
--- a/drm/nouveau/nvkm/subdev/volt/base.c
+++ b/drm/nouveau/nvkm/subdev/volt/base.c
@@ -51,18 +51,37 @@ 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, err, 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);
+ if (i == 0) {
+ best = 0;
+ err = volt->vid[i].uv - uv;
+ } else {
+ int new_err = volt->vid[i].uv - uv;
+ if (abs(new_err) < abs(err)
+ || (err < 0 && new_err >= 0)) {
+ best = i;
+ err = new_err;
+ }
+ }
+
+ if (err == 0) {
+ ret = volt->func->vid_set(volt, volt->vid[best].vid);
nvkm_debug(subdev, "set %duv: %d\n", uv, ret);
break;
}
}
+
+ if (best != -1) {
+ 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;
}
The code is really weird though :o How about the following? It would
make it much more readable and actually do what your commit message says.
int best = -1;
u32 best_abs_err = -1;
for (i = 0; i < volt->vid_nr; i++) {
int abs_err = abs(volt->vid[i].uv - uv);
if (volt->vid[i].uv >= uv && abs_err < best_abs_err) {
best = i;
best_abs_err = abs_err;
if (abs_err == 0)
break;
}
}
if (best >= 0) {
ret = volt->func->vid_set(volt, volt->vid[best].vid);
nvkm_debug(subdev, "set %duv: %d\n", uv, ret);
} else {
/* return an error to tell that we cannot use the wanted clock since we
cannot select the needed voltage! */
}
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