On Fri, Oct 08, 2010 at 12:22:28PM +0100, Jonathan Cameron wrote:
> *bump* For anyone from spi side of things.
>
> Quick summary of question (hence top post :)
> Is it ever wrong to over specify elements of a transfer?
> We have a driver that (for historical reasons) specifies
> that a particular transfer is 8 bit.
> .bits_per_word = 8,
>
> This causes issues with the atmel spi driver which sees that
> the value is specified and hence fails the transfer.
>
> Who needs to fix?
Sounds to me like the Atmel SPI driver is deficient.
g.
>
> Obviously we can work around by dropping the specification that it
> is 8 bits per word.
>
> Thanks,
>
> Jonathan
>
> On 09/29/10 14:52, Jonathan Cameron wrote:
> > Hi Matthias
> >
> > Lots of additional cc's as I think I know what the problem is and I
> > think it's an spi issue rather than an IIO one.
> >
> >>
> >> after a long stuggle, I got a working kernel version for my board
> >> running as I need it.
> >> I tried both the staging/adis16255 and the staging/iio/gyro driver.
> >>
> >> The latter doesn't work.
> >> "adis16260 spi1.1: problem when reading 16 bit register 0x34
> >> iio device0: disable irq failed"
> > That is the first actual comms with the chip, so it is likely to be a
> > general issue rather than due to that particular call.
> >>
> >> A quick look in the code of staging/adis16255 and the data sheet tells
> >> me, that you have to read from the higher register address but we read
> >> from the lower one.
> >> So I changed the value to 0x35, but it doesn't work either.
> > Quoting from the data sheet (it is present on the sheets for both chips).
> >
> > "Each register has two addresses (upper, lower), but either one can be used
> > to access its entire 16 bits of data."
> >
> > It could be there is something special about that register I'm not seeing
> > though...
> >>
> >> Well in the end I copied "my" read version from staging/adis16255 and
> >> put a read call in the probe function (because it is the easiest way
> >> to get spi_device structure).
> >> Then it seems to work, with higher and lower byte.
> > Ok, that gives us something to work against which is very helpful!
> >> So my conclusion is, that something went wrong when you casacade and
> >> discascade (sorry for the poor english), from spi_device through
> >> adis16260_state to device.
> >> Sounds stange to me, as it works with the adis16260 chip, right?
> > As far as I know. It's possible something strange happened in a merge
> > at some point though.
> >> So maybe it's because I use avr32 architecture?
> >
> > Having done a bit of digging and made sure that (up to the fact I don't
> > have the part) everything runs normally on my board, I'm beginning to
> > suspect you are correct. There are some subtle differences in the setup
> > between your code and Barry's.
> >
> > Looking about, the avr32's seem to use the atmel_spi driver?
> >
> > Ah got it (I think)...
> >
> > In drivers/spi/atmel_spi.c atmel_spi_transfer we have:
> >
> > /* FIXME implement these protocol options!! */
> > if (xfer->bits_per_word || xfer->speed_hz) {
> > dev_dbg(&spi->dev, "no protocol options yet\n");
> > return -ENOPROTOOPT;
> > }
> >
> > Personally I'd have at least sanity checked if the parameters were trying
> > to change anything before dumping out. Also, surely that's a case for
> > something screaming a little louder given it is an out and out device
> > killing problem? I think the default is 8 bit? I think the reason it
> > is in Barry's driver is a legacy issue to do with the fact that these
> > are actually 16bit transfers pretending to be 8 bits ones... Actually
> > now I look at it, I'm not sure why he didn't use 16 bit ones in that
> > function in the first place!
> >
> > Not sure we need it in our drivers, but I'm guessing there may be some
> > spi master driver out there somewhere that defaults to something other than
> > 8 bit? (have vague recollection of seeing an email about this... perhaps
> > someone who plays more with spi bus drivers?)
> >
> >>
> >> So I don't know if we should dig deeper. The problem is, that I don't
> >> have too much time to do it...
> > Sorry it is proving such a pain for you to test!
> >> What do you think?
> > I have cc'd spi people and the atmel_spi maintainer to see what we think
> > is the correct fix for this. For the purposes of this discussion
> > (though it's isn't quite what Matthias is working with) the driver in
> > question is drivers/staging/iio/gyro/adis16260_core.c
> >
> >
> > Thanks again for testing.
> >
> > Jonathan
> >
> >> Regards,
> >> Matthias
> >>
> >> 2010/9/27 Jonathan Cameron <[email protected]>:
> >>> On 09/18/10 16:48, matthias wrote:
> >>>> Hi Jonathan,
> >>>>
> >>>> sorry for not answering yet. I was on vacation and next week I won't
> >>>> be able to test the driver. Will try to do it asap....
> >>>>
> >>>> Matthias
> >>>
> >>> Hi Matthias,
> >>>
> >>> I'm afraid quite a bit has changed over the last few weeks. Feel free to
> >>> test
> >>> this patch set. The changes since then are merely renames of a couple of
> >>> attributes and a lot of stuff for event handling that doesn't effect this
> >>> driver.
> >>>
> >>> If not, I'm hosting a *temporary* git tree with all my various queued up
> >>> changes
> >>> at:
> >>>
> >>> http://git.kernel.org/?p=linux/kernel/git/jic23/iio_temp.git
> >>>
> >>> Seems excessive to post this set again until I hear back from you!
> >>>
> >>> Thanks,
> >>>
> >>> Jonathan
> >>>
> >>> p.s. Switched to [email protected] address as that now seems to work.
> >>>
> >>>>
> >>>> 2010/9/18 Jonathan Cameron <[email protected]>:
> >>>>> On 09/06/10 16:16, Jonathan Cameron wrote:
> >>>>>> Mainly a rebase, but a couple of attribute naming fixes as well.
> >>>>>>
> >>>>>> Note I don't have one of these so if anyone could test that would
> >>>>>> be great!
> >>>>>>
> >>>>>> Signed-off-by: Jonathan Cameron <[email protected]>
> >>>>>>
> >>>>>> Jonathan Cameron (2):
> >>>>>> staging:iio:adis16260 add id table support
> >>>>>> staging:iio:adis16260 add suppport for adis16255 and adis16250.
> >>>>>>
> >>>>>> drivers/staging/iio/gyro/Kconfig | 8 +-
> >>>>>> drivers/staging/iio/gyro/adis16260.h | 3 +
> >>>>>> drivers/staging/iio/gyro/adis16260_core.c | 139
> >>>>>> ++++++++++++++------
> >>>>>> drivers/staging/iio/gyro/adis16260_platform_data.h | 19 +++
> >>>>>> drivers/staging/iio/gyro/gyro.h | 9 ++
> >>>>>> 5 files changed, 136 insertions(+), 42 deletions(-)
> >>>>>> create mode 100644 drivers/staging/iio/gyro/adis16260_platform_data.h
> >>>>>>
> >>>>>>
> >>>>> Whilst I haven't tested these (don't have the hardware) I don't think
> >>>>> there
> >>>>> is anything controversial, so my intent is to push these to Greg before
> >>>>> the
> >>>>> next merge window. This is primarily to remove the duplication we
> >>>>> currently
> >>>>> have with two drivers that effectively cover the same parts.
> >>>>>
> >>>>> Thanks,
> >>>>>
> >>>>> Jonathan
> >>>>>
> >>>>
> >>>>
> >>>>
> >>>
> >>>
> >>
> >>
> >>
> >
> > --
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> > the body of a message to [email protected]
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
>
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