diff options
Diffstat (limited to 'target/linux/mvebu/patches-3.10/0086-irqchip-armada-370-xp-fix-MSI-race-condition.patch')
| -rw-r--r-- | target/linux/mvebu/patches-3.10/0086-irqchip-armada-370-xp-fix-MSI-race-condition.patch | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/target/linux/mvebu/patches-3.10/0086-irqchip-armada-370-xp-fix-MSI-race-condition.patch b/target/linux/mvebu/patches-3.10/0086-irqchip-armada-370-xp-fix-MSI-race-condition.patch new file mode 100644 index 0000000000..ebbc532391 --- /dev/null +++ b/target/linux/mvebu/patches-3.10/0086-irqchip-armada-370-xp-fix-MSI-race-condition.patch @@ -0,0 +1,44 @@ +From ddda6fa410b6e50ee67d4a628187e76b4a6c9b28 Mon Sep 17 00:00:00 2001 +From: Lior Amsalem <alior@marvell.com> +Date: Mon, 25 Nov 2013 17:26:45 +0100 +Subject: [PATCH 086/203] irqchip: armada-370-xp: fix MSI race condition + +In the Armada 370/XP driver, when we receive an IRQ 1, we read the +list of doorbells that caused the interrupt from register +ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS. This gives the list of MSIs that +were generated. However, instead of acknowledging only the MSIs that +were generated, we acknowledge *all* the MSIs, by writing +~MSI_DOORBELL_MASK in the ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register. + +This creates a race condition: if a new MSI that isn't part of the +ones read into the temporary "msimask" variable is fired before we +acknowledge all MSIs, then we will simply loose it. + +It is important to mention that this ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS +register has the following behavior: "A CPU write of 0 clears the bits +in this field. A CPU write of 1 has no effect". This is what allows us +to simply write ~msimask to acknoledge the handled MSIs. + +Notice that the same problem is present in the IPI implementation, but +it is fixed as a separate patch, so that this IPI fix can be pushed to +older stable versions as appropriate (all the way to 3.8), while the +MSI code only appeared in 3.13. + +Signed-off-by: Lior Amsalem <alior@marvell.com> +Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> +Cc: Thomas Gleixner <tglx@linutronix.de> +--- + drivers/irqchip/irq-armada-370-xp.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +--- a/drivers/irqchip/irq-armada-370-xp.c ++++ b/drivers/irqchip/irq-armada-370-xp.c +@@ -381,7 +381,7 @@ armada_370_xp_handle_irq(struct pt_regs + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS) + & PCI_MSI_DOORBELL_MASK; + +- writel(~PCI_MSI_DOORBELL_MASK, per_cpu_int_base + ++ writel(~msimask, per_cpu_int_base + + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS); + + for (msinr = PCI_MSI_DOORBELL_START; |