linux_old1/include
Jean Delvare 424ed67c7d i2c-algo-bit: Implement a 50/50 SCL duty cycle
The original i2c-algo-bit implementation uses a 33/66 SCL duty cycle
when bits are being written on the bus. While the I2C specification
doesn't forbid it, this prevents us from driving the I2C bus to its
max speed, limiting us to 66 kbps max on standard I2C busses.

Implementing a 50/50 duty cycle instead lets us max out the bandwidth
up to the theoretical max of 100 kbps on standard I2C busses. This is
particularly important when large amounts of data need to be transfered
over the bus, as is the case with some TV adapters when the firmware is
being uploaded.

In fact this change even allows, at least in theory, fast-mode I2C
support at 125, 166 and 250 kbps. There's no way to reach the
theoretical max of 400 kbps with this implementation. But I don't
think we want to put efforts in that direction anyway: software-driven
I2C is very CPU-intensive and bad for latency.

Other timing changes:
* Don't set SDA high explicitly on error, we're going to issue a stop
  condition before we leave anyway.
* If an error occurs when sending the slave address, yield the CPU
  before retrying, and remove the additional delay after the new start
  condition.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
2007-05-01 23:26:33 +02:00
..
acpi ACPI: Disable MSI on request of FADT 2007-04-25 01:13:47 -04:00
asm-alpha Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6 2007-04-27 09:29:04 -07:00
asm-arm [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-arm26 [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-avr32 Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2007-04-27 09:26:46 -07:00
asm-cris [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-frv [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-generic Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2007-04-27 09:26:46 -07:00
asm-h8300 [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-i386 [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-ia64 [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-m32r [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-m68k [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-m68knommu [PATCH] m68knommu: GPIO line defines for the ColdFire 5282 2007-03-06 18:08:38 -08:00
asm-mips Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2007-04-27 09:26:46 -07:00
asm-parisc [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-powerpc Merge branch 'for-2.6.22' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc 2007-04-30 08:10:12 -07:00
asm-ppc [POWERPC] Stop using ppc_sys for Xilinx Virtex boards 2007-04-30 11:02:04 +10:00
asm-s390 Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2007-04-27 09:26:46 -07:00
asm-sh Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6 2007-04-27 09:29:04 -07:00
asm-sh64 [NET]: Introduce SIOCGSTAMPNS ioctl to get timestamps with nanosec resolution 2007-04-25 22:24:04 -07:00
asm-sparc Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6 2007-04-27 09:29:04 -07:00
asm-sparc64 Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6 2007-04-27 09:29:04 -07:00
asm-um [NET]: div64_64 consolidate (rev3) 2007-04-25 22:23:33 -07:00
asm-v850 [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-x86_64 [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
asm-xtensa [NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support 2007-04-25 22:24:21 -07:00
crypto [CRYPTO] api: Allow multiple frontends per backend 2007-02-07 09:21:01 +11:00
keys [AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both 2007-04-26 15:48:28 -07:00
linux i2c-algo-bit: Implement a 50/50 SCL duty cycle 2007-05-01 23:26:33 +02:00
math-emu
media i2c: Cleanup the includes of <linux/i2c.h> 2007-05-01 23:26:29 +02:00
mtd UBI: Unsorted Block Images 2007-04-27 14:23:33 +03:00
net Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2007-04-30 08:14:42 -07:00
pcmcia serial: Add PCMCIA IDs for Quatech DSP-100 dual RS232 adapter. 2007-02-16 15:19:16 -08:00
rdma RDMA/cma: Add multicast communication support 2007-02-16 14:29:07 -08:00
rxrpc [AF_RXRPC]: Delete the old RxRPC code. 2007-04-26 15:55:48 -07:00
scsi Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6 2007-02-19 13:32:28 -08:00
sound [ALSA] version 1.0.14rc3 2007-03-14 08:25:52 +01:00
video [PATCH] Video: fb, add true ref_count atomicity 2007-02-12 09:48:42 -08:00
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