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SubjectRe: [PATCH 3/4] ACPI: Introduce DMA ranges parsing
On Mon, Jul 24, 2017 at 08:42:15PM +0200, Rafael J. Wysocki wrote:
> On Mon, Jul 24, 2017 at 12:40 PM, Lorenzo Pieralisi
> <lorenzo.pieralisi@arm.com> wrote:
> > On Sat, Jul 22, 2017 at 12:15:42AM +0200, Rafael J. Wysocki wrote:
> >
>
> [cut]
>
> >
> >> > + return -EINVAL;
> >> > + }
> >> > +
> >> > + ret = acpi_dev_get_dma_resources(adev, &list);
> >> > + if (ret > 0) {
> >> > + list_for_each_entry(rentry, &list, node) {
> >> > + if (dma_offset && rentry->offset != dma_offset) {
> >> > + ret = -EINVAL;
> >> > + pr_warn("Can't handle multiple windows with different offsets\n");
> >> > + goto out;
> >> > + }
> >> > + dma_offset = rentry->offset;
> >> > +
> >> > + /* Take lower and upper limits */
> >> > + if (rentry->res->start < dma_start)
> >> > + dma_start = rentry->res->start;
> >> > + if (rentry->res->end > dma_end)
> >> > + dma_end = rentry->res->end;
> >> > + }
> >> > +
> >> > + if (dma_start >= dma_end) {
> >> > + ret = -EINVAL;
> >> > + pr_warn("Invalid DMA regions configuration\n");
> >>
> >> dev_warn()?
> >>
> >> And why _warn() and not _info()?
> >
> > Mmm..ok for the dev_ prefix - basically this would be a FW_BUG (I think
> > this specific error condition is overkill TBH, the ACPI resource
> > validation code should catch it before we even get here) not sure
> > about downgrading it to _info() though, I would leave it at this
> > loglevel - in particular in the offset check above:
> >
> > if (dma_offset && rentry->offset != dma_offset) {
> > ret = -EINVAL;
> > pr_warn("Can't handle multiple windows with different offsets\n");
> > goto out;
> > }
>
> Well, so the "why" question above still has no answer ...

It is a firmware misconfiguration, we end up dismissing firmware
information and use the device with default/possibly misconfigured
DMA windows (ie offset == 0) for that platform, that's the reason
why I thought it would deserve a _warn rather than _info loglevel.

Thanks,
Lorenzo

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