On Thu, Jul 17, 2014 at 05:40:50PM +0200, Tomasz Figa wrote: > Hi Jason, > > On 17.07.2014 17:32, Jason Cooper wrote: > > 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@xxxxxxx> > >> Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx> > >> Signed-off-by: Tomasz Figa <t.figa@xxxxxxxxxxx> > >> --- > >> 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? > > Could be, although there was and still is no topology data specified in > DT for affected Exynos SoCs. The need for it showed up just recently, so > I'm not sure this is a regression to fix in older kernels. In my "the kernel and the dtb aren't tied together" quest, these are the kinds of things I like to see fixed in stable kernels. If a user needs to update a dtb, say to fix a bug, it's reasonable to use the newest one for a given board. After all, any new nodes won't change anything, since the driver in the kernel won't match the node. However, in this case, without this fix, a user upgrading to the newest dtb would get a broken system. So, this fix should be backported to prevent the breakage. Or, have I missed something in my analysis? thx, Jason. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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