pci: Clamp pcie_set_readrq() when using "performance" settings
authorBenjamin Herrenschmidt <benh@kernel.crashing.org>
Fri, 14 Oct 2011 19:56:15 +0000 (14:56 -0500)
committerJesse Barnes <jbarnes@virtuousgeek.org>
Thu, 27 Oct 2011 19:45:44 +0000 (12:45 -0700)
commita1c473aa11e61bc871be16279c9bf976acf22504
tree13f1c4565817bab8660e2e38f8fedc5344519788
parent62f392ea5b5f87b641e16e61a4cedda21ef7341f
pci: Clamp pcie_set_readrq() when using "performance" settings

When configuring the PCIe settings for "performance", we allow parents
to have a larger Max Payload Size than children and rely on children
Max Read Request Size to not be larger than their own MPS to avoid
having the host bridge generate responses they can't cope with.

However, various drivers in Linux call pci_set_readrq() with arbitrary
values, assuming this to be a simple performance tweak. This breaks
under our "performance" configuration.

Fix that by making sure the value programmed by pcie_set_readrq() is
never larger than the configured MPS for that device.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Jon Mason <mason@myri.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
drivers/pci/pci.c