linux-kernel - Re: [PATCH] irqchip: gic: Fix core ID calculation when topology is read from DT

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Date:	Thu, 17 Jul 2014 11:32:36 -0400
From:	Jason Cooper <jason@...edaemon.net>
To:	Tomasz Figa <t.figa@...sung.com>
Cc:	linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Kukjin Kim <kgene.kim@...sung.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Subject: Re: [PATCH] irqchip: gic: Fix core ID calculation when topology is
 read from DT

On Thu, Jul 17, 2014 at 05:23:44PM +0200, Tomasz Figa wrote:
> Certain GIC implementation, namely those found on earlier, single
> cluster, Exynos SoCs, have registers mapped without per-CPU banking,
> which means that the driver needs to use different offset for each CPU.
> 
> Currently the driver calculates the offset by multiplying value returned
> by cpu_logical_map() by CPU offset parsed from DT. This is correct when
> CPU topology is not specified in DT and aforementioned function returns
> core ID alone. However when DT contains CPU topology, the function
> changes to return cluster ID as well, which is non-zero on mentioned
> SoCs and so breaks the calculation in GIC driver.
> 
> This patch fixes this by masking out cluster ID in CPU offset
> calculation so that only core ID is considered. Multi-cluster Exynos
> SoCs already have banked GIC implementations, so this simple fix should
> be enough.
> 
> Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Signed-off-by: Tomasz Figa <t.figa@...sung.com>
> ---
>  drivers/irqchip/irq-gic.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

iiuc, this was introduced by:

  db0d4db22a78d ARM: gic: allow GIC to support non-banked setups

and so should be for v3.3 and up, correct?

thx,

Jason.
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