From 3af779eb172b0438f77e8a01a97dd0eb9a146076 Mon Sep 17 00:00:00 2001 From: Luka Perkov Date: Tue, 11 Feb 2014 02:07:41 +0000 Subject: mvebu: backport mainline patches from kernel 3.12 This is a backport of the patches accepted to the Linux mainline related to mvebu SoC (Armada XP and Armada 370) between Linux v3.11, and Linux v3.12. This work mainly covers: * Ground work for sharing the pxa nand driver(drivers/mtd/nand/pxa3xx_nand.c) between the PXA family,and the Armada family. * Further updates to the mvebu MBus. * Work and ground work for enabling MSI on the Armada family. * some phy / mdio bus initialization related work. * Device tree binding documentation update. Signed-off-by: Seif Mazareeb CC: Luka Perkov SVN-Revision: 39565 --- ...chip-armada-370-xp-fix-IPI-race-condition.patch | 46 ++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch (limited to 'target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch') diff --git a/target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch b/target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch new file mode 100644 index 0000000000..336ad8d758 --- /dev/null +++ b/target/linux/mvebu/patches-3.10/0085-irqchip-armada-370-xp-fix-IPI-race-condition.patch @@ -0,0 +1,46 @@ +From 60b78d28057f9f1ecce39955755d26e4cd3130de Mon Sep 17 00:00:00 2001 +From: Lior Amsalem +Date: Mon, 25 Nov 2013 17:26:44 +0100 +Subject: [PATCH 085/203] irqchip: armada-370-xp: fix IPI race condition + +In the Armada 370/XP driver, when we receive an IRQ 0, we read the +list of doorbells that caused the interrupt from register +ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS. This gives the list of IPIs that +were generated. However, instead of acknowledging only the IPIs that +were generated, we acknowledge *all* the IPIs, by writing +~IPI_DOORBELL_MASK in the ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register. + +This creates a race condition: if a new IPI that isn't part of the +ones read into the temporary "ipimask" variable is fired before we +acknowledge all IPIs, then we will simply loose it. This is causing +scheduling hangs on SMP intensive workloads. + +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 ~ipimask to acknoledge the handled IPIs. + +Notice that the same problem is present in the MSI implementation, but +it will be 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 +Signed-off-by: Thomas Petazzoni +Cc: stable@vger.kernel.org +Cc: Thomas Gleixner +--- + 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 +@@ -407,7 +407,7 @@ armada_370_xp_handle_irq(struct pt_regs + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS) + & IPI_DOORBELL_MASK; + +- writel(~IPI_DOORBELL_MASK, per_cpu_int_base + ++ writel(~ipimask, per_cpu_int_base + + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS); + + /* Handle all pending doorbells */ -- cgit v1.2.3