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From:   Lecopzer Chen <lecopzer.chen@mediatek.com>
To:     <maz@kernel.org>
CC:     <julien.thierry.kdev@gmail.com>, <lecopzer.chen@mediatek.com>,
        <lecopzer@gmail.com>, <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <lorenzo.pieralisi@arm.com>,
        <tglx@linutronix.de>, <yj.chiang@mediatek.com>
Subject: Re: [PATCH] irqchip/gic-v3: Fix IPRIORITYR can't perform byte operations in GIC-600
Date:   Tue, 30 Mar 2021 22:24:40 +0800
Message-ID: <20210330142440.30119-1-lecopzer.chen@mediatek.com>
In-Reply-To: <87eefwrash.wl-maz@kernel.org>
References: <87eefwrash.wl-maz@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

[...]
> > > > 
> > > > From the architecture spec:
> > > > 
> > > > <quote>
> > > > 11.1.3 GIC memory-mapped register access
> > > > 
> > > > In any system, access to the following registers must be supported:
> > > > 
> > > > [...]
> > > > * Byte accesses to:
> > > > 	- GICD_IPRIORITYR<n>.
> > > > 	- GICD_ITARGETSR<n>.
> > > > 	- GICD_SPENDSGIR<n>.
> > > > 	- GICD_CPENDSGIR<n>.
> > > > 	- GICR_IPRIORITYR<n>.
> > > > </quote>
> > > > 
> > > > So if GIC600 doesn't follow this architectural requirement, this is a
> > > > HW erratum, and I want an actual description of the HW issue together
> > > > with an erratum number.
> > > > 
> > > > Lorenzo, can you please investigate on your side?
> > > 
> > > Sure - I will look into it and report back.
> > 
> > Checked - I don't think this patch is needed so it should be dropped and
> > a follow-up discussion can continue in the relevant/appropriate forum -
> > if there is anything left to discuss.
> 
> Thanks for having had a look. This really smells like an integration
> issue rather than an actual GIC bug.
> 
> Lecopzer, please check with your HW people and potentially ARM, as I
> think you are looking at the wrong problem.

Thanks a lot for the suggestion and checking,

I think I'll back to disscuss with ARM and our HW team to figure out
the previous answer from ARM Support in detail.

Thanks again!


Lecopzer