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linux-next/drivers
Mauro Carvalho Chehab 3d3215c4e4 V4L/DVB (12411): em28xx: Fix artifacts with Silvercrest webcam
Silvercrest mt9v011 sensor produces a 640x480 image. However,
previously, the code were getting only half of the lines and merging two
consecutive frames to "produce" a 640x480 image.

With the addition of progressive mode, now em28xx is working with a full
image. However, when the number of lines is bigger than 240, the
beginning of some odd lines are filled with blank.

After lots of testing, and physically checking the device for a Xtal, it
was noticed experimentally that mt9v011 is using em28xx XCLK as its
clock. Due to that, changing XCLK value changes the maximum speed of the
stream.

At the tests, it were possible to produce up to 32 fps, using a 30 MHz
XCLK. However, at that rate, the artifacts happen even at 320x240. Lower
values of XCLK produces artifacts only at 640x480.

At some values of xclk (for example XCLKK = 6 MHz, 640x480), it is
possible to see an invalid sucession of artifacts with this pattern:

.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
..xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
...xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
....xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
..xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
...xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
....xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

(where the dots represent the blanked pixels)

So, it seems that a waveform in the format of a ramp is interferring at
the image.

The cause of this interference is currently unknown. Some possibilities
are:
	- electrical interference (maybe this device is broken?);
	- some issue at mt9v011 programming;
	- some bug at em28xx chip.

So, for now, let's be conservative and use a value of XCLK that we know
for sure that it won't cause artifacts.

As I'm waiting for more of such devices with different em28xx chipset
revisions, I'll have the opportunity to double check the issue with
other pieces of hardware.

Later patches can vary XCLK depending on the vertical resolutions, if a
proper fix is not discovered.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2009-08-13 20:39:10 -03:00
..
accessibility
acpi Merge branch 'misc-2.6.31' into release 2009-08-02 12:55:51 -04:00
amba [ARM] amba: fix amba device resources 2009-07-05 22:39:08 +01:00
ata ahci: add workaround for on-board 5723s on some gigabyte boards 2009-08-12 06:21:32 -04:00
atm
auxdisplay
base PM / Driver Core: Kill dev_pm_ops platform warning for now 2009-08-10 23:41:18 +02:00
block mg_disk: Add missing ready status check on mg_write() 2009-07-28 08:57:33 +02:00
bluetooth headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
cdrom
char pty: fix data loss when stopped (^S/^Q) 2009-08-10 13:31:18 -07:00
clocksource clocksource: sh_tmu: Make undefined TCOR behaviour less undefined. 2009-06-24 21:08:11 +09:00
connector connector: maintainer/mail update. 2009-07-21 12:43:51 -07:00
cpufreq [CPUFREQ] Make cpufreq suspend code conditional on powerpc. 2009-08-04 14:32:11 -04:00
cpuidle
crypto
dca
dio
dma Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx 2009-07-30 16:46:31 -07:00
edac amd64_edac: print debug statements only on error 2009-08-04 12:10:06 +02:00
eisa
firewire Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2009-07-06 14:03:44 -07:00
firmware
gpio headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
gpu drm/i915: silence vblank warnings 2009-08-09 12:25:29 +10:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2009-07-22 09:30:07 -07:00
hwmon hwmon: (asus_atk0110) Fix upper limit readings 2009-07-28 16:31:39 +02:00
i2c i2c-omap: OMAP3430 Silicon Errata 1.153 2009-07-30 01:03:24 +01:00
ide ide-tape: Don't leak kernel stack information 2009-07-21 20:36:25 -07:00
idle
ieee1394 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2009-07-06 14:03:44 -07:00
ieee802154
infiniband Merge branches 'ehca', 'misc', 'mlx4', 'mthca' and 'nes' into for-linus 2009-06-23 10:38:47 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2009-08-07 10:42:14 -07:00
isdn Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2009-08-04 15:38:34 -07:00
leds Update Yoichi Yuasa's e-mail address 2009-07-03 15:45:29 +01:00
lguest lguest and virtio: cleanup struct definitions to Linux style. 2009-07-30 16:03:46 +09:30
macintosh powerpc/pmac: Fix DMA ops for MacIO devices 2009-06-26 14:37:25 +10:00
mca
md md: allow upper limit for resync/reshape to be set when array is read-only 2009-08-13 10:41:50 +10:00
media V4L/DVB (12411): em28xx: Fix artifacts with Silvercrest webcam 2009-08-13 20:39:10 -03:00
memstick
message fusion: mptsas, fix lock imbalance 2009-06-22 08:54:14 -05:00
mfd mfd: twl4030 irq fixes 2009-08-04 20:31:32 +02:00
misc cb710: use SG_MITER_TO_SG/SG_MITER_FROM_SG 2009-07-31 12:28:46 +02:00
mmc drivers/mmc: correct error-handling code 2009-08-07 10:39:56 -07:00
mtd Remove zero-length file drivers/mtd/maps/sbc8240.c 2009-08-12 06:29:57 -04:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2009-08-04 15:38:34 -07:00
nubus
of of/mdio: Add support function for Ethernet fixed-link property 2009-07-22 09:27:18 -07:00
oprofile oprofile: reset bt_lost_no_mapping with other stats 2009-07-10 12:35:36 +02:00
parisc parisc: hppb.c - fix printk format strings 2009-08-02 15:42:39 +02:00
parport parport/serial: add support for NetMos 9901 Multi-IO card 2009-06-30 18:55:59 -07:00
pci Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2009-08-10 11:00:37 -07:00
pcmcia Remove multiple KERN_ prefixes from printk formats 2009-07-08 10:30:03 -07:00
platform Merge branch 'bugzilla-13825' into release 2009-08-02 12:36:01 -04:00
pnp Merge branches 'acerhdf', 'acpi-pci-bind', 'bjorn-pci-root', 'bugzilla-12904', 'bugzilla-13121', 'bugzilla-13396', 'bugzilla-13533', 'bugzilla-13612', 'c3_lock', 'hid-cleanups', 'misc-2.6.31', 'pdc-leak-fix', 'pnpacpi', 'power_nocheck', 'thinkpad_acpi', 'video' and 'wmi' into release 2009-06-24 01:19:50 -04:00
power Merge git://git.infradead.org/users/cbou/battery-2.6.31 2009-07-30 16:45:53 -07:00
pps
ps3
rapidio
regulator
rtc rtc: mark if rtc-cmos drivers were successfully registered 2009-07-29 19:10:35 -07:00
s390 Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6 2009-08-04 15:38:10 -07:00
sbus
scsi Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2009-08-04 15:38:34 -07:00
serial Merge master.kernel.org:/home/rmk/linux-2.6-arm 2009-08-07 10:46:51 -07:00
sh
sn
spi spi: omap2_mcspi rxdma bugfix 2009-07-29 19:10:35 -07:00
ssb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2009-07-09 20:33:18 -07:00
staging Staging: rspiusb: Fix buffer overflow 2009-08-07 16:12:03 -07:00
tc
telephony headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
thermal
uio
usb USB: fix oops on disconnect in cdc-acm 2009-08-07 16:05:14 -07:00
uwb
video i.MX31: fix framebuffer locking regressions 2009-08-07 10:39:56 -07:00
virtio virtio: refactor find_vqs 2009-07-30 16:03:45 +09:30
vlynq vlynq: fix typo in Kconfig to enable debugging 2009-07-06 13:57:03 -07:00
w1 drivers/w1/masters/omap_hdq.c: fix missing mutex unlock 2009-08-07 10:39:55 -07:00
watchdog Merge master.kernel.org:/home/rmk/linux-2.6-arm 2009-08-07 10:46:51 -07:00
xen xen: Use kcalloc() in xen_init_IRQ() 2009-07-01 11:19:47 +02:00
zorro
Kconfig
Makefile