Hi, On Thu, Sep 19, 2013 at 07:36:33AM -0500, Nishanth Menon wrote: > On 09/19/2013 07:20 AM, George Cherian wrote: > > On 9/19/2013 5:37 PM, Nishanth Menon wrote: > >> On 09/19/2013 03:13 AM, George Cherian wrote: > >>> On 9/18/2013 11:06 PM, Felipe Balbi wrote: > >>>> Hi, > >>>> > >>>> On Wed, Sep 18, 2013 at 07:18:04PM +0200, Laurent Pinchart wrote: > >>>>> On Wednesday 18 September 2013 13:16:27 Linus Walleij wrote: > >>>>>> On Tue, Sep 17, 2013 at 9:07 PM, Felipe Balbi <balbi@xxxxxx> wrote: > >>>>>>> has anyone ever successfully using gpio-pcf857x.c driver with 16-bit > >>>>>>> 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... > >>>>>> Bouncing the question to George, Laurent and Kuninori... > >>>>> I've got a board with a PCF8575 chip, but it uses I/Os 8 to 14 only as far as > >>>>> 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. > >>>> alright, that'd help me a lot :-) Just want to make sure if we're having > >>>> a board issue, or PCF8575 is a bit screwy ;-) > >>> Is it on dra7x-evm if so which pcf device (i2c address)? > >>> 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. > >> When I look at the data sheet for PCF8575[1] Page 7, Figure 4 Write > >> 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] > > > > I read it as an octal numbering. > >> Note: bits 8,9 are missing not supported. > > > > In octal there is no 8 and 9 > > Where is octal coming into play here? P8 and 9 does not exist as per > the data sheet -> look at the pinout on page 1[1] ->P00-P17 this is > exactly what is described on page 2[1]: > "The number of data bytes that can be sent successively is not limited > After every two bytes, the previous data is overwritten. When the > PCF8575 receives the pairs of data bytes, the first byte is referred > to as P07 – P00 and the second byte as P17 – P10. The third byte > is referred to as P07 – P00, the fourth byte as P17 – P10, and so > on" > > For someone reading schematics and setting up the P15, if the person > uses gpios = <&PCF8575 15 OF_GPIO_HIGH>; this will result in offset = > 15, and as a result 0x80 will be send in byte 3, which from h/w point > of view is P13 which could be controlling something weird! you missed one detail only. I said GPIO15, not P15 :-) GPIO15 on that device is P17 ;-) -- balbi
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