On Wed, Aug 15, 2012 at 12:08 PM, Opensource [Anthony Olech] <[email protected]> wrote: > [Me]
>> > + if (offset > 1) >> > + return -EINVAL; >> So there are two GPIO pins, 0 and 1? That seems odd, but OK. > > That is a feature of the hardware. I believe that calling them "0" and > "1" is the correct thing to do. Correct me if they should have been > called "1" and "2", or something else. It's correct, what I thought was odd was the fact that there were only two GPIO pins on this device. But some have only one even, just wanted to verify... > HANDLING NIBBLES > ================ > > The handling of nibbles within a byte follows the rule that constants > for the nibble NOT being operated on have those bits set to zero, > and thus only bits being operated on may be non-zero. Thus to set, > for example, the value 0xB into the MSH the operation is: > byte &= ~0xF0 > byte |= 0xB0 > it being obvious that it is the upper nibble being operated on. > It seems that you are following a different rule for handling nibbles, > and I can't find any standard for doing so in the kernel, so could > you send me your reference documents? In this case as stated elsewhere, I'm happy that you do things this way, if you #define the magic values you're using in your bytes and nibbles, because else it's just hard to read. #define FOO_MASK 0xF0 #define BAR_FEATURE 0xB0 byte &= ~FOO_MASK; byte |= BAR_FEATURE; It's more readble. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
