linux-kernel - [PATCH 3.16 013/346] ARM: mvebu: fix HW I/O coherency related deadlocks

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Message-ID: <lsq.1479082460.507514731@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Gregory CLEMENT" <gregory.clement@...e-electrons.com>,
        "Terry Stockert" <stockert@...blotadmirer.me>,
        "Thomas Petazzoni" <thomas.petazzoni@...e-electrons.com>,
        "Romain Perier" <romain.perier@...e-electrons.com>
Subject: [PATCH 3.16 013/346] ARM: mvebu: fix HW I/O coherency related
 deadlocks

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>

commit c5379ba8fccd99d5f99632c789f0393d84a57805 upstream.

Until now, our understanding for HW I/O coherency to work on the
Cortex-A9 based Marvell SoC was that only the PCIe regions should be
mapped strongly-ordered. However, we were still encountering some
deadlocks, especially when testing the CESA crypto engine. After
checking with the HW designers, it was concluded that all the MMIO
registers should be mapped as strongly ordered for the HW I/O coherency
mechanism to work properly.

This fixes some easy to reproduce deadlocks with the CESA crypto engine
driver (dmcrypt on a sufficiently large disk partition).

Tested-by: Terry Stockert <stockert@...blotadmirer.me>
Tested-by: Romain Perier <romain.perier@...e-electrons.com>
Cc: Terry Stockert <stockert@...blotadmirer.me>
Cc: Romain Perier <romain.perier@...e-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@...e-electrons.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/arm/mach-mvebu/coherency.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -315,22 +315,16 @@ static void __init armada_370_coherency_
 }
 
 /*
- * This ioremap hook is used on Armada 375/38x to ensure that PCIe
- * memory areas are mapped as MT_UNCACHED instead of MT_DEVICE. This
- * is needed as a workaround for a deadlock issue between the PCIe
- * interface and the cache controller.
+ * This ioremap hook is used on Armada 375/38x to ensure that all MMIO
+ * areas are mapped as MT_UNCACHED instead of MT_DEVICE. This is
+ * needed for the HW I/O coherency mechanism to work properly without
+ * deadlock.
  */
 static void __iomem *
-armada_pcie_wa_ioremap_caller(phys_addr_t phys_addr, size_t size,
-			      unsigned int mtype, void *caller)
+armada_wa_ioremap_caller(phys_addr_t phys_addr, size_t size,
+			 unsigned int mtype, void *caller)
 {
-	struct resource pcie_mem;
-
-	mvebu_mbus_get_pcie_mem_aperture(&pcie_mem);
-
-	if (pcie_mem.start <= phys_addr && (phys_addr + size) <= pcie_mem.end)
-		mtype = MT_UNCACHED;
-
+	mtype = MT_UNCACHED;
 	return __arm_ioremap_caller(phys_addr, size, mtype, caller);
 }
 
@@ -339,7 +333,7 @@ static void __init armada_375_380_cohere
 	struct device_node *cache_dn;
 
 	coherency_cpu_base = of_iomap(np, 0);
-	arch_ioremap_caller = armada_pcie_wa_ioremap_caller;
+	arch_ioremap_caller = armada_wa_ioremap_caller;
 
 	/*
 	 * We should switch the PL310 to I/O coherency mode only if