linux/drivers
Anatolij Gustschin a646bd7f08 dma: ipu_idmac: do not lose valid received data in the irq handler
Currently when two or more buffers are queued by the camera driver
and so the double buffering is enabled in the idmac, we lose one
frame comming from CSI since the reporting of arrival of the first
frame is deferred by the DMAIC_7_EOF interrupt handler and reporting
of the arrival of the last frame is not done at all. So when requesting
N frames from the image sensor we actually receive N - 1 frames in
user space.

The reason for this behaviour is that the DMAIC_7_EOF interrupt
handler misleadingly assumes that the CUR_BUF flag is pointing to the
buffer used by the IDMAC. Actually it is not the case since the
CUR_BUF flag will be flipped by the FSU when the FSU is sending the
<TASK>_NEW_FRM_RDY signal when new frame data is delivered by the CSI.
When sending this singal, FSU updates the DMA_CUR_BUF and the
DMA_BUFx_RDY flags: the DMA_CUR_BUF is flipped, the DMA_BUFx_RDY
is cleared, indicating that the frame data is beeing written by
the IDMAC to the pointed buffer. DMA_BUFx_RDY is supposed to be
set to the ready state again by the MCU, when it has handled the
received data. DMAIC_7_CUR_BUF flag won't be flipped here by the
IPU, so waiting for this event in the EOF interrupt handler is wrong.
Actually there is no spurious interrupt as described in the comments,
this is the valid DMAIC_7_EOF interrupt indicating reception of the
frame from CSI.

The patch removes code that waits for flipping of the DMAIC_7_CUR_BUF
flag in the DMAIC_7_EOF interrupt handler. As the comment in the
current code denotes, this waiting doesn't help anyway. As a result
of this removal the reporting of the first arrived frame is not
deferred to the time of arrival of the next frame and the drivers
software flag 'ichan->active_buffer' is in sync with DMAIC_7_CUR_BUF
flag, so the reception of all requested frames works.

This has been verified on the hardware which is triggering the
image sensor by the programmable state machine, allowing to
obtain exact number of frames. On this hardware we do not tolerate
losing frames.

This patch also removes resetting the DMA_BUFx_RDY flags of
all channels in ipu_disable_channel() since transfers on other
DMA channels might be triggered by other running tasks and the
buffers should always be ready for data sending or reception.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Reviewed-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Tested-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2011-02-14 02:28:16 -08:00
..
accessibility
acpi ACPI / PM: Call suspend_nvs_free() earlier during resume 2011-01-20 18:30:17 -08:00
amba
ata kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
atm
auxdisplay
base kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
block
bluetooth
cdrom
char Merge branch 'akpm' 2011-01-20 17:02:14 -08:00
clk
clocksource
connector
cpufreq kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
cpuidle
crypto
dca
dio
dma dma: ipu_idmac: do not lose valid received data in the irq handler 2011-02-14 02:28:16 -08:00
edac
eisa
firewire Merge branches 'fixes' and 'fwnet' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 2011-01-21 13:34:39 -08:00
firmware kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
gpio
gpu Merge branch 'akpm' 2011-01-20 17:02:14 -08:00
hid kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
hwmon
i2c
ide kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
idle
ieee802154
infiniband kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
input kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
isdn
leds drivers/leds/ledtrig-gpio.c: make output match input, tighten input checking 2011-01-20 17:02:06 -08:00
lguest lguest: compile fixes 2011-01-20 21:37:29 +10:30
macintosh powerpc/macintosh: Fix wrong test in fan_{read,write}_reg() 2011-01-21 14:08:34 +11:00
mca
md
media Merge branch 'media_fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2011-01-21 16:50:31 -08:00
memstick
message
mfd
misc
mmc
mtd
net kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
nfc
nubus
of
oprofile
parisc
parport
pci kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
pcmcia kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
platform
pnp
power
pps
ps3
rapidio
regulator
rtc
s390 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2011-01-19 20:25:45 -08:00
sbus
scsi
sfi
sh
sn
spi
ssb kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
staging [media] staging/lirc: fix mem leaks and ptr err usage 2011-01-19 12:52:22 -02:00
target
tc
telephony
thermal
tty Merge branch 'akpm' 2011-01-20 17:02:14 -08:00
uio
usb kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
uwb
vhost
video backlight: fix 88pm860x_bl macro collision 2011-01-20 17:02:06 -08:00
virtio virtio: remove virtio-pci root device 2011-01-20 21:37:30 +10:30
vlynq
w1
watchdog
xen Merge branch 'xen/xenbus' of git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen 2011-01-20 16:37:28 -08:00
zorro
Kconfig
Makefile Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 2011-01-20 16:39:23 -08:00