From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
alan@lxorguk.ukuu.org.uk,
Russell King <rmk+kernel@arm.linux.org.uk>,
Jason Cooper <jason@lakedaemon.net>
Subject: [ 01/27] Dove: Attempt to fix PMU/RTC interrupts
Date: Thu, 6 Dec 2012 16:58:45 -0800 [thread overview]
Message-ID: <20121207005825.584911563@linuxfoundation.org> (raw)
In-Reply-To: <20121207005825.232489605@linuxfoundation.org>
3.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
commit 5d3df935426271016b895aecaa247101b4bfa35e upstream.
Fix the acknowledgement of PMU interrupts on Dove: some Dove hardware
has not been sensibly designed so that interrupts can be handled in a
race free manner. The PMU is one such instance.
The pending (aka 'cause') register is a bunch of RW bits, meaning that
these bits can be both cleared and set by software (confirmed on the
Armada-510 on the cubox.)
Hardware sets the appropriate bit when an interrupt is asserted, and
software is required to clear the bits which are to be processed. If
we write ~(1 << bit), then we end up asserting every other interrupt
except the one we're processing. So, we need to do a read-modify-write
cycle to clear the asserted bit.
However, any interrupts which occur in the middle of this cycle will
also be written back as zero, which will also clear the new interrupts.
The upshot of this is: there is _no_ way to safely clear down interrupts
in this register (and other similarly behaving interrupt pending
registers on this device.) The patch below at least stops us creating
new interrupts.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/mach-dove/irq.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
--- a/arch/arm/mach-dove/irq.c
+++ b/arch/arm/mach-dove/irq.c
@@ -45,8 +45,20 @@ static void pmu_irq_ack(struct irq_data
int pin = irq_to_pmu(d->irq);
u32 u;
+ /*
+ * The PMU mask register is not RW0C: it is RW. This means that
+ * the bits take whatever value is written to them; if you write
+ * a '1', you will set the interrupt.
+ *
+ * Unfortunately this means there is NO race free way to clear
+ * these interrupts.
+ *
+ * So, let's structure the code so that the window is as small as
+ * possible.
+ */
u = ~(1 << (pin & 31));
- writel(u, PMU_INTERRUPT_CAUSE);
+ u &= readl_relaxed(PMU_INTERRUPT_CAUSE);
+ writel_relaxed(u, PMU_INTERRUPT_CAUSE);
}
static struct irq_chip pmu_irq_chip = {
next prev parent reply other threads:[~2012-12-07 0:58 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-07 0:58 [ 00/27] 3.6.10-stable review Greg Kroah-Hartman
2012-12-07 0:58 ` Greg Kroah-Hartman [this message]
2012-12-07 0:58 ` [ 02/27] Dove: Fix irq_to_pmu() Greg Kroah-Hartman
2012-12-07 0:58 ` [ 03/27] drm/radeon/dce4+: dont use radeon_crtc for vblank callback Greg Kroah-Hartman
2012-12-07 0:58 ` [ 04/27] drm/radeon: properly handle mc_stop/mc_resume on evergreen+ (v2) Greg Kroah-Hartman
2012-12-07 0:58 ` [ 05/27] drm/radeon: properly track the crtc not_enabled case evergreen_mc_stop() Greg Kroah-Hartman
2012-12-07 0:58 ` [ 06/27] mm/vmemmap: fix wrong use of virt_to_page Greg Kroah-Hartman
2012-12-07 0:58 ` [ 07/27] mm: vmscan: fix endless loop in kswapd balancing Greg Kroah-Hartman
2012-12-07 0:58 ` [ 08/27] mm: soft offline: split thp at the beginning of soft_offline_page() Greg Kroah-Hartman
2012-12-07 0:58 ` [ 09/27] target: Fix handling of aborted commands Greg Kroah-Hartman
2012-12-07 0:58 ` [ 10/27] iwlwifi: fix the basic CCK rates calculation Greg Kroah-Hartman
2012-12-07 0:58 ` [ 11/27] ARM: Kirkwood: Update PCI-E fixup Greg Kroah-Hartman
2012-12-07 0:58 ` [ 12/27] x86, fpu: Avoid FPU lazy restore after suspend Greg Kroah-Hartman
2012-12-07 0:58 ` [ 13/27] workqueue: exit rescuer_thread() as TASK_RUNNING Greg Kroah-Hartman
2012-12-07 0:58 ` [ 14/27] mac80211: fix remain-on-channel (non-)cancelling Greg Kroah-Hartman
2012-12-07 0:58 ` [ 15/27] md/raid1{,0}: fix deadlock in bitmap_unplug Greg Kroah-Hartman
2012-12-07 0:59 ` [ 16/27] i7300_edac: Fix error flag testing Greg Kroah-Hartman
2012-12-07 0:59 ` [ 17/27] Revert "sched, autogroup: Stop going ahead if autogroup is disabled" Greg Kroah-Hartman
2012-12-07 17:22 ` Joseph Salisbury
2012-12-07 17:30 ` Joseph Salisbury
2012-12-09 23:41 ` Ben Hutchings
2012-12-07 17:31 ` Greg Kroah-Hartman
2012-12-07 17:43 ` Joseph Salisbury
2012-12-07 0:59 ` [ 18/27] bnx2x: remove redundant warning log Greg Kroah-Hartman
2012-12-07 0:59 ` [ 19/27] i7core_edac: fix panic when accessing sysfs files Greg Kroah-Hartman
2012-12-07 0:59 ` [ 20/27] s390/mm: have 16 byte aligned struct pages Greg Kroah-Hartman
2012-12-07 10:00 ` Heiko Carstens
2012-12-07 15:07 ` Greg Kroah-Hartman
2012-12-07 0:59 ` [ 21/27] net: qmi_wwan: adding more ZTE devices Greg Kroah-Hartman
2012-12-07 0:59 ` [ 22/27] net: qmi_wwan: add Huawei E173 Greg Kroah-Hartman
2012-12-07 0:59 ` [ 23/27] ACPI: missing break Greg Kroah-Hartman
2012-12-07 0:59 ` [ 24/27] i915: Quirk no_lvds on Gigabyte GA-D525TUD ITX motherboard Greg Kroah-Hartman
2012-12-07 4:36 ` Calvin Walton
2012-12-07 16:37 ` Greg Kroah-Hartman
2012-12-07 0:59 ` [ 25/27] drm/i915: Add no-lvds quirk for Supermicro X7SPA-H Greg Kroah-Hartman
2012-12-07 0:59 ` [ 26/27] x86, amd: Disable way access filter on Piledriver CPUs Greg Kroah-Hartman
2012-12-07 0:59 ` [ 27/27] 8139cp: revert "set ring address before enabling receiver" Greg Kroah-Hartman
2012-12-07 13:36 ` [ 00/27] 3.6.10-stable review Holger Hoffstaette
2012-12-08 0:46 ` Shuah Khan
2012-12-08 0:58 ` Shuah Khan
2012-12-08 5:40 ` satoru takeuchi
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