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authorJulia Lemire <jlemire@matrox.com>2013-03-18 10:17:47 -0400
committerDave Airlie <airlied@redhat.com>2013-03-21 10:16:58 +1000
commit260b3f1291a75a580d22ce8bfb1499c617272716 (patch)
tree9ef4924aed8ded896b87950da034282ad681d6e3 /drivers/gpu/drm/mgag200
parent236f651bf79ab7d521bdacf4753ddd0764334980 (diff)
downloadlinux-linaro-stable-260b3f1291a75a580d22ce8bfb1499c617272716.tar.gz
drm/mgag200: Bug fix: Modified pll algorithm for EH project
While testing the mgag200 kms driver on the HP ProLiant Gen8, a bug was seen. Once the bootloader would load the selected kernel, the screen would go black. At first it was assumed that the mgag200 kms driver was hanging. But after setting up the grub serial output, it was seen that the driver was being loaded properly. After trying serval monitors, one finaly displayed the message "Frequency Out of Range". By comparing the kms pll algorithm with the previous mgag200 xorg driver pll algorithm, discrepencies were found. Once the kms pll algorithm was modified, the expected pll values were produced. This fix was tested on several monitors of varying native resolutions. Signed-off-by: Julia Lemire <jlemire@matrox.com> Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/gpu/drm/mgag200')
-rw-r--r--drivers/gpu/drm/mgag200/mgag200_mode.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index a274b9906ef8..fe22bb780e1d 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -382,19 +382,19 @@ static int mga_g200eh_set_plls(struct mga_device *mdev, long clock)
m = n = p = 0;
vcomax = 800000;
vcomin = 400000;
- pllreffreq = 3333;
+ pllreffreq = 33333;
delta = 0xffffffff;
permitteddelta = clock * 5 / 1000;
- for (testp = 16; testp > 0; testp--) {
+ for (testp = 16; testp > 0; testp >>= 1) {
if (clock * testp > vcomax)
continue;
if (clock * testp < vcomin)
continue;
for (testm = 1; testm < 33; testm++) {
- for (testn = 1; testn < 257; testn++) {
+ for (testn = 17; testn < 257; testn++) {
computed = (pllreffreq * testn) /
(testm * testp);
if (computed > clock)
@@ -404,11 +404,11 @@ static int mga_g200eh_set_plls(struct mga_device *mdev, long clock)
if (tmpdelta < delta) {
delta = tmpdelta;
n = testn - 1;
- m = (testm - 1) | ((n >> 1) & 0x80);
+ m = (testm - 1);
p = testp - 1;
}
if ((clock * testp) >= 600000)
- p |= 80;
+ p |= 0x80;
}
}
}