On 09/19/2013 03:13 AM, George Cherian wrote:On 9/18/2013 11:06 PM, Felipe Balbi wrote:When I look at the data sheet for PCF8575[1] Page 7, Figure 4 WriteHi,Is it on dra7x-evm if so which pcf device (i2c address)?
On Wed, Sep 18, 2013 at 07:18:04PM +0200, Laurent Pinchart wrote:On Wednesday 18 September 2013 13:16:27 Linus Walleij wrote:alright, that'd help me a lot :-) Just want to make sure if we're havingOn Tue, Sep 17, 2013 at 9:07 PM, Felipe Balbi <balbi@xxxxxx> wrote:I've got a board with a PCF8575 chip, but it uses I/Os 8 to 14 only as far ashas anyone ever successfully using gpio-pcf857x.c driver with 16-bitBouncing the question to George, Laurent and Kuninori...
gpio expanders ? We're having some issues here where toggling the last
gpio pin (gpio 15) on a PCF8575 device causes platform to hang and I
can't come up with any explanation of why would it hang...
I know.
I can try toggling I/O 15, but that will need to wait until next week as I'm
currently travelling without access to the hardware.
a board issue, or PCF8575 is a bit screwy ;-)
The pins i were interested were only 1 and 2 I never tried pin 15.
Just tried toggling through sysfs and it works for me.
mode (output)
I see the data writes are of the order:
I2c 1's byte: address
I2c 2'nd byte:P[7-0]
I2c 3rd byte:P[17-10]
Note: bits 8,9 are missing not supported.
Now [2] claims that it does support PCF8575, however when I look at
line 143[3]
unsigned bit = 1 << offset;
[snip]
if (value)
gpio->out |= bit;
else
gpio->out &= ~bit;
There is no handling for the skip needed for bits 8 and 9.. Seems to
me like a driver bug.
[1] http://www.ti.com/lit/ds/symlink/pcf8575.pdf
[2]
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpio-pcf857x.c
[3]
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpio-pcf857x.c#n143