On Fri, Sep 27, 2013 at 06:51:53AM -0400, Will Deacon wrote:
> On Fri, Sep 27, 2013 at 11:23:59AM +0100, Andreas Herrmann wrote:
> > On Fri, Sep 27, 2013 at 05:51:57AM -0400, Will Deacon wrote:
> > > Hi Andreas,
> > >
> > > On Thu, Sep 26, 2013 at 11:36:14PM +0100, Andreas Herrmann wrote:
> > > > Currently it is derived from smmu resource size. In case of a
> > > > mismatchin between the two calculations trust DT more than register
> > > > values and overwrite cb_base.
> > >
> > > I thought the driver already favoured the DT?
> > >
> > > > @@ -1702,12 +1704,23 @@ static int arm_smmu_device_cfg_probe(struct
> > > > arm_smmu_device *smmu)
> > > >
> > > > /* Check that we ioremapped enough */
> > > > size = 1 << (((id >> ID1_NUMPAGENDXB_SHIFT) &
> > > > ID1_NUMPAGENDXB_MASK) + 1);
> > > > - size *= (smmu->pagesize << 1);
> > > > + size *= smmu->pagesize;
> > > > + smmu->cb_base = smmu->base + size;
> > > > + size *= 2;
> > > > +
> > > > if (smmu->size < size)
> > > > dev_warn(smmu->dev,
> > > > "device is 0x%lx bytes but only mapped
> > > > 0x%lx!\n",
> > > > size, smmu->size);
> > > >
> > > > + t = (unsigned long) smmu->base + (smmu->size >> 1);
> > > > + if ((unsigned long)smmu->cb_base != t) {
> > > > + dev_warn(smmu->dev, "address space mismatch, "
> > > > + "overwriting cb_base (old: 0x%lx, new:
> > > > 0x%lx)\n",
> > > > + (unsigned long) smmu->cb_base, t);
> > > > + smmu->cb_base = (void *) t;
> > > > + }
> > > > +
> > >
> > > I expect I'm just being slow here (only one coffee in), but I can't see
> > > what
> > > this gets us over the current use of resource_size (which goes and uses
> > > the
> > > DT).
> >
> > On balance it adds a warning if there is an inconsistency between the
> > resource size and the relevant registers describing the SMMU address
> > space.
>
> Well, we should already print the "device is 0x%lx bytes but only mapped
> 0x%lx!" message, which I think is enough to go and figure out what happened.
No, you can map a larger region and still wrongly calculate cb_base
w/o this warning.
So the required check is something like
/* Check for mismatch between SMMU address space size and size of
mapped region */
size = 1 << (((id >> ID1_NUMPAGENDXB_SHIFT) & ID1_NUMPAGENDXB_MASK) +
1);
size *= (smmu->pagesize << 1);
if (smmu->size != size)
dev_warn(smmu->dev,
"SMMU_GLOBAL_SIZE (0x%lx) differs from mapped "
region size (0x%lx)!\n", size, smmu->size);
Andreas
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