From mboxrd@z Thu Jan 1 00:00:00 1970 From: thierry.reding@gmail.com (Thierry Reding) Date: Tue, 22 Nov 2016 12:26:19 +0100 Subject: [RFC PATCH 04/11] PCI: tegra: limit to MMU build only In-Reply-To: <28079479.jInxCWkYlm@wuerfel> References: <1479806768-39911-1-git-send-email-vladimir.murzin@arm.com> <11637152.Dd0IBkEQ8q@wuerfel> <58341297.9090303@arm.com> <28079479.jInxCWkYlm@wuerfel> Message-ID: <20161122112619.GA22862@ulmo.ba.sec> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Nov 22, 2016 at 10:54:01AM +0100, Arnd Bergmann wrote: > On Tuesday, November 22, 2016 9:40:39 AM CET Vladimir Murzin wrote: > > On 22/11/16 09:31, Arnd Bergmann wrote: > > > On Tuesday, November 22, 2016 9:26:01 AM CET Vladimir Murzin wrote: > > >> This driver uses functionality which available for MMU build only, > > >> thus add dependency on MMU. > > >> > > >> Cc: Thierry Reding > > >> Signed-off-by: Vladimir Murzin > > >> > > > > > > Can you be more specific about what requires the MMU here? > > > > > > Is it the I/O space remapping or something else? > > > > Yes it comes from I/O space remapping. > > > > The fill error log: > > > > CC drivers/pci/host/pci-tegra.o > > In file included from ./arch/arm/include/asm/page.h:22:0, > > from ./arch/arm/include/asm/thread_info.h:17, > > from ./include/linux/thread_info.h:58, > > from ./include/asm-generic/current.h:4, > > from ./arch/arm/include/generated/asm/current.h:1, > > from ./include/linux/mutex.h:13, > > from ./include/linux/notifier.h:13, > > from ./include/linux/clk.h:17, > > from drivers/pci/host/pci-tegra.c:29: > > drivers/pci/host/pci-tegra.c: In function 'tegra_pcie_bus_alloc': > > drivers/pci/host/pci-tegra.c:388:27: error: 'L_PTE_PRESENT' undeclared (first use in this function) > > pgprot_t prot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | > > > That is not the I/O space, that is the config space. > > Not sure what a better alternative would be, but the manual selection > of page flags makes the driver non-portable and dependent on architecture > specifics that it really shouldn't have to worry about. > > In common PCI code, we use pgprot_device(PAGE_KERNEL)) at some point, > and that sounds like the right thing to do, but ARM doesn't provide > an override for it and the fallback is pgprot_noncached(), which is > probably wrong here. Actually I think pgprot_noncached() is correct. Very early on we used to map this using ioremap() and I remember that working. I also just tested the pci-tegra driver with pgprot_device(PAGE_KERNEL) instead of the ARM- specific flags and it seems to work well. Thierry -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: not available URL: