From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Mon, 09 Jan 2017 12:52:01 +0100 Subject: [QUESTION] Early Write Acknowledge for PCIe configuration space In-Reply-To: References: <6092525.UgRCY3dpzP@wuerfel> Message-ID: <1882721.jqIYnAaWfQ@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Monday, January 9, 2017 10:59:47 AM CET John Garry wrote: > On 06/01/2017 11:24, Arnd Bergmann wrote: > > On Friday, January 6, 2017 11:15:22 AM CET John Garry wrote: > > > > Probably nobody thought about this properly in the Linux drivers. The > > ARMv8 ARM sounds correct here. > > > > I/O space may have the same issue, as it also requires non-posted > > accesses. > > Right, so our HW team's recommendation - from ARM's memory model and > also PCIe order model - is that not only config space but also PCIe > memory mapped IO has the same attribute (nE). Just to be sure we are talking about the same thing: "PCIe memory mapped IO" could refer to either PCI I/O space or PCI memory space. As far as I can tell, PCI memory space should *not* be using the nE attribute, while PCI I/O space and PCI config space should. Does this match what your HW team recomments? Arnd