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

[Julien Grall <julien@xen.org>]

On 06/05/2022 12:28, Bertrand Marquis wrote:
>> On 4 May 2022, at 18:15, Rahul Singh <Rahul.Singh@arm.com> 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@arm.com>
> Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

Committed. Thanks!

Cheers,

-- 
Julien Grall