[F][PATCH 0/1] ZPCI used write back addresses by default but should use write through (LP: 1866162)

[frank.heimes at canonical.com]

Buglink: https://bugs.launchpad.net/bugs/1866162

In the initial MIO support, introduced in commit 71ba41c9b1d9 ("s390/pci: provide support for MIO instructions"),
setting up the PCI BAR resources defaults to using the mio_wb address as the resource's start address.
This means users of the mapping, which includes most drivers, will get write combining on PCI Stores.
But this may lead to problems when drivers expect write through behavior when not using an explicit ioremap_wc(),
which is the default behavior on other platforms.
This patch/commit changes the default to write through.
It has already been reviewed, is currently queued to be send for Linux 5.6-rc5 with a CC stable tag, and already in linux-next (20200305).

Niklas Schnelle (1):
  From: Niklas Schnelle <schnelle at linux.ibm.com>

 arch/s390/pci/pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

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2.25.0