From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Guenter Roeck To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Guenter Roeck Subject: [PATCH] PCI: Only enable IO window if supported Date: Fri, 22 May 2015 17:52:16 -0700 Message-Id: <1432342336-25832-1-git-send-email-linux@roeck-us.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: The PCI subsystem always assumes that I/O is supported on PCIe bridges and tries to assign an I/O window to each port even if that is not the case. This may result in messages such as pcieport 0000:02:00.0: res[7]=[io 0x1000-0x0fff] get_res_add_size add_size 1000 pcieport 0000:02:00.0: BAR 7: no space for [io size 0x1000] pcieport 0000:02:00.0: BAR 7: failed to assign [io size 0x1000] for each bridge port, even if a port or its parent does not support I/O in the first place. To avoid this message, check if a port supports I/O before trying to enable it. Also check if port's parent supports I/O, and only modify a port's I/O resource size if both the port and its parent support I/O. If IO is disabled after the initial port scan, the IO base and size registers are set to 0x00f0 to indicate that IO is disabled. A later rescan interprets this as "IO supported" and enables the IO range, even if the parent does not support IO. Handle this situation as well. Signed-off-by: Guenter Roeck --- drivers/pci/probe.c | 14 ++++++++++++++ drivers/pci/setup-bus.c | 4 ++-- include/linux/pci.h | 9 +++++++++ 3 files changed, 25 insertions(+), 2 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 6675a7a1b9fc..f4944ef45148 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -354,6 +354,20 @@ static void pci_read_bridge_io(struct pci_bus *child) base = (io_base_lo & io_mask) << 8; limit = (io_limit_lo & io_mask) << 8; + /* If necessary, check if the bridge supports an I/O aperture */ + if (!io_base_lo && !io_limit_lo) { + u16 io; + + if (!pci_parent_supports_io(child)) + return; + + pci_write_config_word(dev, PCI_IO_BASE, 0xe0f0); + pci_read_config_word(dev, PCI_IO_BASE, &io); + pci_write_config_word(dev, PCI_IO_BASE, 0x0); + if (!io) + return; + } + if ((io_base_lo & PCI_IO_RANGE_TYPE_MASK) == PCI_IO_RANGE_TYPE_32) { u16 io_base_hi, io_limit_hi; diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 4fd0cacf7ca0..963b31a109a9 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -750,12 +750,12 @@ static void pci_bridge_check_ranges(struct pci_bus *bus) b_res[1].flags |= IORESOURCE_MEM; pci_read_config_word(bridge, PCI_IO_BASE, &io); - if (!io) { + if (!io && pci_parent_supports_io(bus)) { pci_write_config_word(bridge, PCI_IO_BASE, 0xe0f0); pci_read_config_word(bridge, PCI_IO_BASE, &io); pci_write_config_word(bridge, PCI_IO_BASE, 0x0); } - if (io) + if (io && (io != 0x00f0 || pci_parent_supports_io(bus))) b_res[0].flags |= IORESOURCE_IO; /* DECchip 21050 pass 2 errata: the bridge may miss an address diff --git a/include/linux/pci.h b/include/linux/pci.h index 353db8dc4c6e..f3de9e24aab1 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -489,6 +489,15 @@ static inline bool pci_is_root_bus(struct pci_bus *pbus) return !(pbus->parent); } +/* + * Returns true if the parent bus supports an I/O aperture. + */ +static inline bool pci_parent_supports_io(struct pci_bus *pbus) +{ + return pci_is_root_bus(pbus) || pci_is_root_bus(pbus->parent) || + (pbus->parent->resource[0]->flags & IORESOURCE_IO); +} + /** * pci_is_bridge - check if the PCI device is a bridge * @dev: PCI device -- 2.1.0