Date: Sat, 9 Dec 2006 12:41:25 +0100 From: Bernd Walter <ticso@cicely12.cicely.de> To: "M. Warner Losh" <imp@bsdimp.com> Cc: ticso@cicely12.cicely.de, freebsd-arm@freebsd.org, ticso@cicely.de Subject: Re: questions about current RM9200 state Message-ID: <20061209114124.GB54209@cicely12.cicely.de> In-Reply-To: <20061208.223200.-1303464500.imp@bsdimp.com> References: <20061207.205008.-432839162.imp@bsdimp.com> <20061208104227.GH54209@cicely12.cicely.de> <20061208114906.GJ54209@cicely12.cicely.de> <20061208.223200.-1303464500.imp@bsdimp.com>
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On Fri, Dec 08, 2006 at 10:32:00PM -0700, M. Warner Losh wrote:
> In message: <20061208114906.GJ54209@cicely12.cicely.de>
> Bernd Walter <ticso@cicely12.cicely.de> writes:
> : On Fri, Dec 08, 2006 at 11:42:28AM +0100, Bernd Walter wrote:
> : > On Thu, Dec 07, 2006 at 08:50:08PM -0700, M. Warner Losh wrote:
> : > > In message: <20061208015032.GF54209@cicely12.cicely.de>
> : > > Bernd Walter <ticso@cicely12.cicely.de> writes:
> : > > : But I can't probe the bus from userland:
> : > > : [56]arm9# ./iic_probe /dev/iic0
> : > > : - and nothing listed.
> : > >
> : > > twi doesn't support START/STOP ioctls that you use. Hmmm, that's in
> : > > p4 that I've removed them because I never got that working. I also
> : > > think the version in -head isn't the latest, working one. I think you
> : > > do the same thing with a 0 byte transfer. Except we don't detect
> : > > NOACK quite right yet, I'm afraid. I'd expect an error each time you
> : > > tried.
> : >
> : > Ah - Ok, will switch to 0 Byte transfers and retest.
> :
> : iic.c:
> : case I2CWRITE:
> : if (s->count <= 0) {
> : error = EINVAL;
> : break;
> : }
> :
> : Well - it wouldn't work without NOACK detection anyway.
>
> I think a zero-byte transfer would do it.
Unfortunately the TWI controller can't do zero transfers at all :(
I thought the RM9200 has different one, but it is the same ^$%@ as in
the AT91SAM7 series, which I already had some hard time with.
The TWI controller in the AVR series is much better IMHO.
I'll send you a diff later today to fix some small bugs that I've found
in the driver - those points aren't documented very well in the
handbook.
--
B.Walter http://www.bwct.de http://www.fizon.de
bernd@bwct.de info@bwct.de support@fizon.de
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