From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Thu, 30 Mar 2017 17:20:16 +0100 Subject: [PATCH v2 07/22] PCI: ECAM: use ioremap_nopost() to map config region In-Reply-To: <20170327094954.7162-8-lorenzo.pieralisi@arm.com> References: <20170327094954.7162-1-lorenzo.pieralisi@arm.com> <20170327094954.7162-8-lorenzo.pieralisi@arm.com> Message-ID: <20170330162015.GB5623@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Mar 27, 2017 at 10:49:35AM +0100, Lorenzo Pieralisi wrote: > Current ECAM kernel implementation uses ioremap() to map the ECAM > configuration space memory region; this is not safe in that on some > architectures the ioremap interface provides mappings that allow posted > write transactions. This, as highlighted in the PCIe specifications > (4.0 - Rev0.3, "Ordering Considerations for the Enhanced Configuration > Address Mechanism"), can create ordering issues for software because > posted writes transactions on the CPU host bus are non posted in the > PCI express fabric. > > Update the ioremap() interface to use ioremap_nopost() whose > mapping attributes guarantee that non-posted writes transactions > are issued for memory writes within the ECAM memory mapped address > region. > > Signed-off-by: Lorenzo Pieralisi > Cc: Bjorn Helgaas > --- > drivers/pci/ecam.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) Acked-by: Will Deacon Will