svn commit: r260165 - head/sys/dev/ahci

[Ian Lepore]

On Wed, 2014-01-01 at 22:32 +0200, Konstantin Belousov wrote:
> On Wed, Jan 01, 2014 at 08:26:08PM +0000, Zbigniew Bodek wrote:
> > Author: zbb
> > Date: Wed Jan  1 20:26:08 2014
> > New Revision: 260165
> > URL: http://svnweb.freebsd.org/changeset/base/260165
> > 
> > Log:
> >   Use only mapped BIOs on ARM
> >   
> >   Using unmapped BIOs causes failure inside bus_dmamap_sync, since
> >   this function requires valid MVA address, which is not present
> >   if mapping is not set up.
> >   
> >   Submitted by:	Wojciech Macek <wma at semihalf.com>
> >   Obtained from:	Semihalf
> > 
> > Modified:
> >   head/sys/dev/ahci/ahci.c
> > 
> > Modified: head/sys/dev/ahci/ahci.c
> > ==============================================================================
> > --- head/sys/dev/ahci/ahci.c	Wed Jan  1 20:22:29 2014	(r260164)
> > +++ head/sys/dev/ahci/ahci.c	Wed Jan  1 20:26:08 2014	(r260165)
> > @@ -3066,7 +3066,15 @@ ahciaction(struct cam_sim *sim, union cc
> >  		if (ch->caps & AHCI_CAP_SPM)
> >  			cpi->hba_inquiry |= PI_SATAPM;
> >  		cpi->target_sprt = 0;
> > +#ifdef __arm__
> > +		/*
> > +		 * Do not use unmapped buffers on ARM. Doing so will cause
> > +		 * failure inside bus_dmamap_sync due to lack of VA.
> > +		 */
> > +		cpi->hba_misc = PIM_SEQSCAN;
> > +#else
> >  		cpi->hba_misc = PIM_SEQSCAN | PIM_UNMAPPED;
> > +#endif
> >  		cpi->hba_eng_cnt = 0;
> >  		if (ch->caps & AHCI_CAP_SPM)
> >  			cpi->max_target = 15;
> 
> I think this is wrong. If bus_dmamap_sync(9) is not functional on arm,
> then unmapped io should be disabled on arm unconditionally, using
> unmapped_buf_allowed.  Why ahci(4) is special in this regard, leaving
> other controllers broken for arm ?

I think this entire concept is wrong, and the fix should be in armv6
busdma or pmap code.  An unmapped page is, by definition, not cached.
The only way data becomes cached is because flags in a mapping indicated
the memory is cacheable.  If we have data from unmapped pages in the
cache, that's a bug in the armv6 pmap implementation, I think.

-- Ian