From mboxrd@z Thu Jan 1 00:00:00 1970 From: helgaas@kernel.org (Bjorn Helgaas) Date: Wed, 21 Sep 2016 14:18:45 -0500 Subject: [PATCH V6 3/5] PCI: thunder-pem: Allow to probe PEM-specific register range for ACPI case In-Reply-To: References: <20160919180900.GB13775@localhost> <49f53bfc-4421-a8b0-694c-bce7e61e1c9e@semihalf.com> <20160920133327.GB13855@localhost> <20160920140518.GD13855@localhost> <20160920191744.GA4941@localhost> <20160921140549.GA11968@red-moon> <20160921180457.GB20006@localhost> Message-ID: <20160921191845.GD20006@localhost> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Sep 21, 2016 at 11:58:22AM -0700, Duc Dang wrote: > On Wed, Sep 21, 2016 at 11:04 AM, Bjorn Helgaas wrote: > > On Wed, Sep 21, 2016 at 03:05:49PM +0100, Lorenzo Pieralisi wrote: > > The existing x86 practice is to use PNP0C02 devices for this purpose, > > and I think we should just follow that practice. > > > > ... > > > > My point is that the hard-coding should not be buried in a driver > > where it's invisible to the rest of the kernel. If we hard-code it in > > a quirk that adds _CRS entries, then the kernel will work just like it > > would if the firmware had been correct in the first place. The > > resource will appear in /sys/devices/pnp*/*/resources and /proc/iomem, > > and if we ever used _SRS to assign or move ACPI devices, we would know > > to avoid the bridge resource. > > Are you suggesting to add code similar to functions in > linux/drivers/pnp/quirks.c to declare/attach the additional resource > that the host need to have when the resource is not in MCFG table? Yes, but what I'm suggesting is actually a little stronger. This has nothing to do with whether a resource is in the MCFG table or not. I'm suggesting ACPI firmware should always describe the resource. If the firmware is defective and doesn't describe it, we should add a quirk in pnp/quirks.c to add a resource for it. Bjorn