Hello,
That's the first time I submit a patch to the Linux kernel. I hope I could do
it right; please forgive me in case of mistakes.
The context: when migrating from Slackware 13.1 to 13.37 (kernel 2.6.33.x to
2.6.37.6), there was some sort of regression with the external webcam installed
at the notebook (0x45:6128, SN9C325+OM6802). In the version 2.6.37.6, the
images got *very* dark, making the webcam almost unusable, unless if used with
direct sunlight.
Tracing back what happened, I concluded that a patch issued in 17/Dec ("[media]
gspca - sonixj: Better handling of the bridge...") caused some sort of odd
effects - including this - to this specific model. Enabling debug in both
versions, the values output to reg17 and reg01 seemed to be different from one
to other, and probably not all of them were made purposedly.
Although the work is not finished, for me it's quite certain that the masking
of the reg17 variable at line 2389 of gspca_sonixj.c (now I'm referring to the
latest version of the file at Linus' tree, as of 14/Jul) is not what the
developer intended to do. It seems to be necessary to negate the mask
MCK_SIZE_MASK when doing the "and" operation, resetting bits 0 to 4 and not the
other; if not, the "or" sentence which follows becomes nonsensical.
So, the patch is simply adding a tilde to the sentence. One character only. :-)
If you could, please review this patch and give me some advice in case of
mistakes.
As said above, this patch by itself is not sufficient to restore proper working
of the webcam (now talking about version 2.6.37.6). I am aware that some
patches which follow seem to fix things broken in that version. But trying to
simply backport the latest version to that kernel version doesn't make the
webcam work again. I'll try to go on making more tests and playing with reg17,
in special, with the latest kernel.
Thanks,
Luiz Carlos Ramos
São Paulo - Brazil
Signed-off-by: Luiz Carlos Ramos <lramos.prof <at> yahoo.com.br>
--- a/drivers/media/video/gspca/sonixj.c 2011-07-14 13:14:41.000000000
-0300
+++ b/drivers/media/video/gspca/sonixj.c 2011-07-14 13:22:26.000000000
-0300
@@ -2386,7 +2386,7 @@ static int sd_start(struct gspca_dev *gs
reg_w1(gspca_dev, 0x01, 0x22);
msleep(100);
reg01 = SCL_SEL_OD | S_PDN_INV;
- reg17 &= MCK_SIZE_MASK;
+ reg17 &= ~MCK_SIZE_MASK; /* that is, reset bits 4..0 */
reg17 |= 0x04; /* clock / 4 */
break;
}
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