Re: acpivout: try to consistently adjust brightness by 5%

[Klemens Nanni]

On Mon, Jan 13, 2020 at 12:20:10PM +0100, Patrick Wildt wrote:
> The problem is that the last two values are 67 and 100.  If you go
> 5% down, it's 95.  The nearest will still be 100.  The code then
> realizes that it's the same level as before, and does nlevel--.
> But nlevel-- is 99, and not 67, because nlevel is the value and
> not the index of the bcl array.  So in essence the change needed
> is to decrease the index, not the value, and then look up the value.
Disucssing this over dinner again, patrick and I independently came up
with the very same diff below.

It makes acpivout_find_brightness() return an index instead a level for
the selected brightness.

Just works on my X230;  I can go through every level with the function
keys and verify with xbacklight(1) that I am indeed not skipping any of
the 16 levels in either direction.

OK?


Index: acpivout.c
===================================================================
RCS file: /cvs/src/sys/dev/acpi/acpivout.c,v
retrieving revision 1.16
diff -u -p -r1.16 acpivout.c
--- acpivout.c  14 Dec 2019 10:57:48 -0000      1.16
+++ acpivout.c  14 Jan 2020 18:50:23 -0000
@@ -165,7 +165,7 @@ acpivout_brightness_cycle(struct acpivou
 void
 acpivout_brightness_step(struct acpivout_softc *sc, int dir)
 {
-       int level, nlevel;
+       int level, nindex;
 
        if (sc->sc_bcl_len == 0)
                return;
@@ -173,17 +173,17 @@ acpivout_brightness_step(struct acpivout
        if (level == -1)
                return;
 
-       nlevel = acpivout_find_brightness(sc, level + (dir * BRIGHTNESS_STEP));
-       if (nlevel == level) {
-               if (dir == 1 && (nlevel + 1 < sc->sc_bcl_len))
-                       nlevel++;
-               else if (dir == -1 && (nlevel - 1 >= 0))
-                       nlevel--;
+       nindex = acpivout_find_brightness(sc, level + (dir * BRIGHTNESS_STEP));
+       if (sc->sc_bcl[nindex] == level) {
+               if (dir == 1 && (nindex + 1 < sc->sc_bcl_len))
+                       nindex++;
+               else if (dir == -1 && (nindex - 1 >= 0))
+                       nindex--;
        }
-       if (nlevel == level)
+       if (sc->sc_bcl[nindex] == level)
                return;
 
-       acpivout_set_brightness(sc, nlevel);
+       acpivout_set_brightness(sc, sc->sc_bcl[nindex]);
 }
 
 void
@@ -219,14 +219,14 @@ acpivout_find_brightness(struct acpivout
        for (i = 0; i < sc->sc_bcl_len - 1; i++) {
                mid = sc->sc_bcl[i] + (sc->sc_bcl[i + 1] - sc->sc_bcl[i]) / 2;
                if (sc->sc_bcl[i] <= level && level <=  mid)
-                       return sc->sc_bcl[i];
+                       return i;
                if  (mid < level && level <= sc->sc_bcl[i + 1])
-                       return sc->sc_bcl[i + 1];
+                       return i + 1;
        }
        if (level < sc->sc_bcl[0])
-               return sc->sc_bcl[0];
+               return 0;
        else
-               return sc->sc_bcl[i];
+               return i;
 }
 
 void
@@ -321,7 +321,7 @@ int
 acpivout_set_param(struct wsdisplay_param *dp)
 {
        struct acpivout_softc   *sc = NULL;
-       int i, exact;
+       int i, nindex;
 
        switch (dp->param) {
        case WSDISPLAYIO_PARAM_BRIGHTNESS:
@@ -335,8 +335,8 @@ acpivout_set_param(struct wsdisplay_para
                }
                if (sc != NULL && sc->sc_bcl_len != 0) {
                        rw_enter_write(&sc->sc_acpi->sc_lck);
-                       exact = acpivout_find_brightness(sc, dp->curval);
-                       acpivout_set_brightness(sc, exact);
+                       nindex = acpivout_find_brightness(sc, dp->curval);
+                       acpivout_set_brightness(sc, sc->sc_bcl[nindex]);
                        rw_exit_write(&sc->sc_acpi->sc_lck);
                        return 0;
                }