Re: [PATCH v2] arm/its: enable LPIs before mapping the collection table

[Julien Grall <julien@xxxxxxx>]

On 06/05/2022 12:28, Bertrand Marquis wrote:
> > On 4 May 2022, at 18:15, Rahul Singh <Rahul.Singh@xxxxxxx> wrote:
> >
> > When Xen boots on the platform that implements the GIC 600, ITS
> > MAPC_LPI_OFF uncorrectable command error issue is observed.
> >
> > As per the GIC-600 TRM (Revision: r1p6) MAPC_LPI_OFF command error can
> > be reported if the MAPC command has tried to map a collection to a core
> > that does not have LPIs enabled. The definition of GICR.EnableLPIs
> > also suggests enabling the LPIs before sending any ITS command that
> > involves LPIs
> >
> > 0b0 LPI support is disabled. Any doorbell interrupt generated as a
> >     result of a write to a virtual LPI register must be discarded,
> >     and any ITS translation requests or commands involving LPIs in
> >     this Redistributor are ignored.
> >
> > 0b1 LPI support is enabled.
> >
> > To fix the MAPC command error issue, enable the LPIs using
> > GICR_CTLR.EnableLPIs before mapping the collection table.
> >
> > gicv3_enable_lpis() is using writel_relaxed(), write to the GICR_CTLR
> > register may not be visible before gicv3_its_setup_collection() send the
> > MAPC command. Use wmb() after writel_relaxed() to make sure register
> > write to enable LPIs is visible.
> >
> > Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
> Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
Committed. Thanks!

Cheers,

--
Julien Grall