From: Jan Glauber <jang@linux.vnet.ibm.com>
Date: Thu, 6 Dec 2012 13:30:28 +0000 (+0100)
Subject: s390/pci: speed up __iowrite64_copy by using pci store block insn
X-Git-Tag: firefly_0821_release~3680^2~1464^2~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=87bc359b9822a73f264f24f3c1b3e4e7e5ed7d72;p=firefly-linux-kernel-4.4.55.git

s390/pci: speed up __iowrite64_copy by using pci store block insn

Benefit from pci store block instruction by writing up to 128 bytes
with a single instruction to MMIO space. Depending on the workload
this can result in a huge performance increase due to the reduced
number of instructions. The ordering guarantees of single stores
vs. one store block are identical.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index b0cef4db2413..bc8935d3e5da 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -355,6 +355,12 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 	return 0;
 }
 
+/* combine single writes by using store-block insn */
+void __iowrite64_copy(void __iomem *to, const void *from, size_t count)
+{
+       zpci_memcpy_toio(to, from, count);
+}
+
 /* Create a virtual mapping cookie for a PCI BAR */
 void __iomem *pci_iomap(struct pci_dev *pdev, int bar, unsigned long max)
 {