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* [PATCH v2 1/2] arm: cns3xxx: fix writing to wrong PCI registers after alignment
@ 2019-01-07 13:45 Koen Vandeputte
  2019-01-07 13:45 ` [PATCH v2 2/2] arm: cns3xxx: use actual size reads for PCIe Koen Vandeputte
  2019-01-24 11:56 ` [PATCH v2 1/2] arm: cns3xxx: fix writing to wrong PCI registers after alignment Lorenzo Pieralisi
  0 siblings, 2 replies; 11+ messages in thread
From: Koen Vandeputte @ 2019-01-07 13:45 UTC (permalink / raw)
  To: linux-arm-kernel
  Cc: linux-pci, Koen Vandeputte, Arnd Bergmann, Bjorn Helgaas,
	Olof Johansson, Robin Leblon, Rob Herring, Russell King, stable

Originally, cns3xxx used it's own functions for mapping, reading and writing registers.

Commit 802b7c06adc7 ("ARM: cns3xxx: Convert PCI to use generic config accessors")
removed the internal PCI config write function in favor of the generic one:

cns3xxx_pci_write_config() --> pci_generic_config_write()

cns3xxx_pci_write_config() expected aligned addresses, being produced by cns3xxx_pci_map_bus()
while the generic one pci_generic_config_write() actually expects the real address
as both the function and hardware are capable of byte-aligned writes.

This currently leads to pci_generic_config_write() writing
to the wrong registers on some ocasions.

First issue seen due to this:

- driver ath9k gets loaded
- The driver wants to write value 0xA8 to register PCI_LATENCY_TIMER, located at 0x0D
- cns3xxx_pci_map_bus() aligns the address to 0x0C
- pci_generic_config_write() effectively writes 0xA8 into register 0x0C (CACHE_LINE_SIZE)

This seems to cause some slight instability when certain PCI devices are used.

Another issue example caused by this this is the PCI bus numbering,
where the primary bus is higher than the secondary, which is impossible.

Before:

00:00.0 PCI bridge: Cavium, Inc. Device 3400 (rev 01) (prog-if 00 [Normal decode])
    Flags: bus master, fast devsel, latency 0, IRQ 255
    Bus: primary=02, secondary=01, subordinate=ff, sec-latency=0

After fix:

00:00.0 PCI bridge: Cavium, Inc. Device 3400 (rev 01) (prog-if 00 [Normal decode])
    Flags: bus master, fast devsel, latency 0, IRQ 255
    Bus: primary=00, secondary=01, subordinate=02, sec-latency=0

And very likely some more ..

Fix all by omitting the alignment being done in the mapping function.

Fixes: 802b7c06adc7 ("ARM: cns3xxx: Convert PCI to use generic config accessors")
Acked-by: Krzysztof Halasa <khalasa@piap.pl>
Acked-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Bjorn Helgaas <bhelgaas@google.com>
CC: Olof Johansson <olof@lixom.net>
CC: Robin Leblon <robin.leblon@ncentric.com>
CC: Rob Herring <robh@kernel.org>
CC: Russell King <linux@armlinux.org.uk>
CC: stable@vger.kernel.org # v4.0+
---
 arch/arm/mach-cns3xxx/pcie.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


V2:
--> resend to be in sync with new second patch
--> added acked-by's based on patch comments

diff --git a/arch/arm/mach-cns3xxx/pcie.c b/arch/arm/mach-cns3xxx/pcie.c
index 318394ed5c7a..5e11ad3164e0 100644
--- a/arch/arm/mach-cns3xxx/pcie.c
+++ b/arch/arm/mach-cns3xxx/pcie.c
@@ -83,7 +83,7 @@ static void __iomem *cns3xxx_pci_map_bus(struct pci_bus *bus,
 	} else /* remote PCI bus */
 		base = cnspci->cfg1_regs + ((busno & 0xf) << 20);
 
-	return base + (where & 0xffc) + (devfn << 12);
+	return base + where + (devfn << 12);
 }
 
 static int cns3xxx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2019-01-31 21:16 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-01-07 13:45 [PATCH v2 1/2] arm: cns3xxx: fix writing to wrong PCI registers after alignment Koen Vandeputte
2019-01-07 13:45 ` [PATCH v2 2/2] arm: cns3xxx: use actual size reads for PCIe Koen Vandeputte
2019-01-08  6:10   ` Krzysztof Hałasa
2019-01-25 10:55   ` Krzysztof Hałasa
2019-01-24 11:56 ` [PATCH v2 1/2] arm: cns3xxx: fix writing to wrong PCI registers after alignment Lorenzo Pieralisi
2019-01-24 15:23   ` Koen Vandeputte
2019-01-24 16:27     ` Lorenzo Pieralisi
2019-01-30 22:08       ` Arnd Bergmann
2019-01-30 23:06         ` Bjorn Helgaas
2019-01-31  8:00           ` Arnd Bergmann
2019-01-31 21:16             ` Bjorn Helgaas

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