From 864d296cf948aef0fa32b81407541572583f7572 Mon Sep 17 00:00:00 2001 From: Chris Wright Date: Wed, 13 Jul 2011 10:14:33 -0700 Subject: PCI: ARI is a PCIe v2 feature The function pci_enable_ari() may mistakenly set the downstream port of a v1 PCIe switch in ARI Forwarding mode. This is a PCIe v2 feature, and with an SR-IOV device on that switch port believing the switch above is ARI capable it may attempt to use functions 8-255, translating into invalid (non-zero) device numbers for that bus. This has been seen to cause Completion Timeouts and general misbehaviour including hangs and panics. Cc: stable@kernel.org Acked-by: Don Dutile Tested-by: Don Dutile Signed-off-by: Chris Wright Signed-off-by: Jesse Barnes --- drivers/pci/pci.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 692671b1166..d549bbc93cd 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1905,7 +1905,7 @@ void pci_enable_ari(struct pci_dev *dev) { int pos; u32 cap; - u16 ctrl; + u16 flags, ctrl; struct pci_dev *bridge; if (!pci_is_pcie(dev) || dev->devfn) @@ -1923,6 +1923,11 @@ void pci_enable_ari(struct pci_dev *dev) if (!pos) return; + /* ARI is a PCIe v2 feature */ + pci_read_config_word(bridge, pos + PCI_EXP_FLAGS, &flags); + if ((flags & PCI_EXP_FLAGS_VERS) < 2) + return; + pci_read_config_dword(bridge, pos + PCI_EXP_DEVCAP2, &cap); if (!(cap & PCI_EXP_DEVCAP2_ARI)) return; -- cgit v1.2.3-70-g09d2 From c9b378c7cbf623649e4ca64f955f2afd12ef01b2 Mon Sep 17 00:00:00 2001 From: Jon Mason Date: Tue, 28 Jun 2011 18:26:25 -0500 Subject: PCI: correct pcie_set_readrq write size When setting the PCI-E MRRS, pcie_set_readrq queries the current settings via a pci_read_config_word call but writes the modified result via a pci_write_config_dword. This results in writing 16 more bits than were queried. Also, the function description comment is slightly incorrect. Signed-off-by: Jon Mason Signed-off-by: Jesse Barnes --- drivers/pci/pci.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index d549bbc93cd..08a95b369d8 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3191,7 +3191,7 @@ EXPORT_SYMBOL(pcie_get_readrq); * @rq: maximum memory read count in bytes * valid values are 128, 256, 512, 1024, 2048, 4096 * - * If possible sets maximum read byte count + * If possible sets maximum memory read request in bytes */ int pcie_set_readrq(struct pci_dev *dev, int rq) { @@ -3214,7 +3214,7 @@ int pcie_set_readrq(struct pci_dev *dev, int rq) if ((ctl & PCI_EXP_DEVCTL_READRQ) != v) { ctl &= ~PCI_EXP_DEVCTL_READRQ; ctl |= v; - err = pci_write_config_dword(dev, cap + PCI_EXP_DEVCTL, ctl); + err = pci_write_config_word(dev, cap + PCI_EXP_DEVCTL, ctl); } out: -- cgit v1.2.3-70-g09d2 From b03e7495a862b028294f59fc87286d6d78ee7fa1 Mon Sep 17 00:00:00 2001 From: Jon Mason Date: Wed, 20 Jul 2011 15:20:54 -0500 Subject: PCI: Set PCI-E Max Payload Size on fabric On a given PCI-E fabric, each device, bridge, and root port can have a different PCI-E maximum payload size. There is a sizable performance boost for having the largest possible maximum payload size on each PCI-E device. However, if improperly configured, fatal bus errors can occur. Thus, it is important to ensure that PCI-E payloads sends by a device are never larger than the MPS setting of all devices on the way to the destination. This can be achieved two ways: - A conservative approach is to use the smallest common denominator of the entire tree below a root complex for every device on that fabric. This means for example that having a 128 bytes MPS USB controller on one leg of a switch will dramatically reduce performances of a video card or 10GE adapter on another leg of that same switch. It also means that any hierarchy supporting hotplug slots (including expresscard or thunderbolt I suppose, dbl check that) will have to be entirely clamped to 128 bytes since we cannot predict what will be plugged into those slots, and we cannot change the MPS on a "live" system. - A more optimal way is possible, if it falls within a couple of constraints: * The top-level host bridge will never generate packets larger than the smallest TLP (or if it can be controlled independently from its MPS at least) * The device will never generate packets larger than MPS (which can be configured via MRRS) * No support of direct PCI-E <-> PCI-E transfers between devices without some additional code to specifically deal with that case Then we can use an approach that basically ignores downstream requests and focuses exclusively on upstream requests. In that case, all we need to care about is that a device MPS is no larger than its parent MPS, which allows us to keep all switches/bridges to the max MPS supported by their parent and eventually the PHB. In this case, your USB controller would no longer "starve" your 10GE Ethernet and your hotplug slots won't affect your global MPS. Additionally, the hotplugged devices themselves can be configured to a larger MPS up to the value configured in the hotplug bridge. To choose between the two available options, two PCI kernel boot args have been added to the PCI calls. "pcie_bus_safe" will provide the former behavior, while "pcie_bus_perf" will perform the latter behavior. By default, the latter behavior is used. NOTE: due to the location of the enablement, each arch will need to add calls to this function. This patch only enables x86. This patch includes a number of changes recommended by Benjamin Herrenschmidt. Tested-by: Jordan_Hargrave@dell.com Signed-off-by: Jon Mason Signed-off-by: Jesse Barnes --- arch/x86/pci/acpi.c | 9 +++ drivers/pci/hotplug/pcihp_slot.c | 45 +----------- drivers/pci/pci.c | 67 ++++++++++++++++++ drivers/pci/probe.c | 145 +++++++++++++++++++++++++++++++++++++++ include/linux/pci.h | 15 +++- 5 files changed, 236 insertions(+), 45 deletions(-) (limited to 'drivers/pci/pci.c') diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c index ae3cb23cd89..c95330267f0 100644 --- a/arch/x86/pci/acpi.c +++ b/arch/x86/pci/acpi.c @@ -360,6 +360,15 @@ struct pci_bus * __devinit pci_acpi_scan_root(struct acpi_pci_root *root) } } + /* After the PCI-E bus has been walked and all devices discovered, + * configure any settings of the fabric that might be necessary. + */ + if (bus) { + struct pci_bus *child; + list_for_each_entry(child, &bus->children, node) + pcie_bus_configure_settings(child, child->self->pcie_mpss); + } + if (!bus) kfree(sd); diff --git a/drivers/pci/hotplug/pcihp_slot.c b/drivers/pci/hotplug/pcihp_slot.c index 749fdf07031..753b21aaea6 100644 --- a/drivers/pci/hotplug/pcihp_slot.c +++ b/drivers/pci/hotplug/pcihp_slot.c @@ -158,47 +158,6 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp) */ } -/* Program PCIE MaxPayload setting on device: ensure parent maxpayload <= device */ -static int pci_set_payload(struct pci_dev *dev) -{ - int pos, ppos; - u16 pctl, psz; - u16 dctl, dsz, dcap, dmax; - struct pci_dev *parent; - - parent = dev->bus->self; - pos = pci_find_capability(dev, PCI_CAP_ID_EXP); - if (!pos) - return 0; - - /* Read Device MaxPayload capability and setting */ - pci_read_config_word(dev, pos + PCI_EXP_DEVCTL, &dctl); - pci_read_config_word(dev, pos + PCI_EXP_DEVCAP, &dcap); - dsz = (dctl & PCI_EXP_DEVCTL_PAYLOAD) >> 5; - dmax = (dcap & PCI_EXP_DEVCAP_PAYLOAD); - - /* Read Parent MaxPayload setting */ - ppos = pci_find_capability(parent, PCI_CAP_ID_EXP); - if (!ppos) - return 0; - pci_read_config_word(parent, ppos + PCI_EXP_DEVCTL, &pctl); - psz = (pctl & PCI_EXP_DEVCTL_PAYLOAD) >> 5; - - /* If parent payload > device max payload -> error - * If parent payload > device payload -> set speed - * If parent payload <= device payload -> do nothing - */ - if (psz > dmax) - return -1; - else if (psz > dsz) { - dev_info(&dev->dev, "Setting MaxPayload to %d\n", 128 << psz); - pci_write_config_word(dev, pos + PCI_EXP_DEVCTL, - (dctl & ~PCI_EXP_DEVCTL_PAYLOAD) + - (psz << 5)); - } - return 0; -} - void pci_configure_slot(struct pci_dev *dev) { struct pci_dev *cdev; @@ -210,9 +169,7 @@ void pci_configure_slot(struct pci_dev *dev) (dev->class >> 8) == PCI_CLASS_BRIDGE_PCI))) return; - ret = pci_set_payload(dev); - if (ret) - dev_warn(&dev->dev, "could not set device max payload\n"); + pcie_bus_configure_settings(dev->bus, dev->bus->self->pcie_mpss); memset(&hpp, 0, sizeof(hpp)); ret = pci_get_hp_params(dev, &hpp); diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 08a95b369d8..466fad6e6ee 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -77,6 +77,8 @@ unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE; unsigned long pci_hotplug_io_size = DEFAULT_HOTPLUG_IO_SIZE; unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE; +enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_PERFORMANCE; + /* * The default CLS is used if arch didn't set CLS explicitly and not * all pci devices agree on the same value. Arch can override either @@ -3222,6 +3224,67 @@ out: } EXPORT_SYMBOL(pcie_set_readrq); +/** + * pcie_get_mps - get PCI Express maximum payload size + * @dev: PCI device to query + * + * Returns maximum payload size in bytes + * or appropriate error value. + */ +int pcie_get_mps(struct pci_dev *dev) +{ + int ret, cap; + u16 ctl; + + cap = pci_pcie_cap(dev); + if (!cap) + return -EINVAL; + + ret = pci_read_config_word(dev, cap + PCI_EXP_DEVCTL, &ctl); + if (!ret) + ret = 128 << ((ctl & PCI_EXP_DEVCTL_PAYLOAD) >> 5); + + return ret; +} + +/** + * pcie_set_mps - set PCI Express maximum payload size + * @dev: PCI device to query + * @rq: maximum payload size in bytes + * valid values are 128, 256, 512, 1024, 2048, 4096 + * + * If possible sets maximum payload size + */ +int pcie_set_mps(struct pci_dev *dev, int mps) +{ + int cap, err = -EINVAL; + u16 ctl, v; + + if (mps < 128 || mps > 4096 || !is_power_of_2(mps)) + goto out; + + v = ffs(mps) - 8; + if (v > dev->pcie_mpss) + goto out; + v <<= 5; + + cap = pci_pcie_cap(dev); + if (!cap) + goto out; + + err = pci_read_config_word(dev, cap + PCI_EXP_DEVCTL, &ctl); + if (err) + goto out; + + if ((ctl & PCI_EXP_DEVCTL_PAYLOAD) != v) { + ctl &= ~PCI_EXP_DEVCTL_PAYLOAD; + ctl |= v; + err = pci_write_config_word(dev, cap + PCI_EXP_DEVCTL, ctl); + } +out: + return err; +} + /** * pci_select_bars - Make BAR mask from the type of resource * @dev: the PCI device for which BAR mask is made @@ -3505,6 +3568,10 @@ static int __init pci_setup(char *str) pci_hotplug_io_size = memparse(str + 9, &str); } else if (!strncmp(str, "hpmemsize=", 10)) { pci_hotplug_mem_size = memparse(str + 10, &str); + } else if (!strncmp(str, "pcie_bus_safe", 13)) { + pcie_bus_config = PCIE_BUS_SAFE; + } else if (!strncmp(str, "pcie_bus_perf", 13)) { + pcie_bus_config = PCIE_BUS_PERFORMANCE; } else { printk(KERN_ERR "PCI: Unknown option `%s'\n", str); diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 795c9026d55..5becf7cd50d 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -856,6 +856,8 @@ void set_pcie_port_type(struct pci_dev *pdev) pdev->pcie_cap = pos; pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, ®16); pdev->pcie_type = (reg16 & PCI_EXP_FLAGS_TYPE) >> 4; + pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, ®16); + pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD; } void set_pcie_hotplug_bridge(struct pci_dev *pdev) @@ -1326,6 +1328,149 @@ int pci_scan_slot(struct pci_bus *bus, int devfn) return nr; } +static int pcie_find_smpss(struct pci_dev *dev, void *data) +{ + u8 *smpss = data; + + if (!pci_is_pcie(dev)) + return 0; + + /* For PCIE hotplug enabled slots not connected directly to a + * PCI-E root port, there can be problems when hotplugging + * devices. This is due to the possibility of hotplugging a + * device into the fabric with a smaller MPS that the devices + * currently running have configured. Modifying the MPS on the + * running devices could cause a fatal bus error due to an + * incoming frame being larger than the newly configured MPS. + * To work around this, the MPS for the entire fabric must be + * set to the minimum size. Any devices hotplugged into this + * fabric will have the minimum MPS set. If the PCI hotplug + * slot is directly connected to the root port and there are not + * other devices on the fabric (which seems to be the most + * common case), then this is not an issue and MPS discovery + * will occur as normal. + */ + if (dev->is_hotplug_bridge && (!list_is_singular(&dev->bus->devices) || + dev->bus->self->pcie_type != PCI_EXP_TYPE_ROOT_PORT)) + *smpss = 0; + + if (*smpss > dev->pcie_mpss) + *smpss = dev->pcie_mpss; + + return 0; +} + +static void pcie_write_mps(struct pci_dev *dev, int mps) +{ + int rc, dev_mpss; + + dev_mpss = 128 << dev->pcie_mpss; + + if (pcie_bus_config == PCIE_BUS_PERFORMANCE) { + if (dev->bus->self) { + dev_dbg(&dev->bus->dev, "Bus MPSS %d\n", + 128 << dev->bus->self->pcie_mpss); + + /* For "MPS Force Max", the assumption is made that + * downstream communication will never be larger than + * the MRRS. So, the MPS only needs to be configured + * for the upstream communication. This being the case, + * walk from the top down and set the MPS of the child + * to that of the parent bus. + */ + mps = 128 << dev->bus->self->pcie_mpss; + if (mps > dev_mpss) + dev_warn(&dev->dev, "MPS configured higher than" + " maximum supported by the device. If" + " a bus issue occurs, try running with" + " pci=pcie_bus_safe.\n"); + } + + dev->pcie_mpss = ffs(mps) - 8; + } + + rc = pcie_set_mps(dev, mps); + if (rc) + dev_err(&dev->dev, "Failed attempting to set the MPS\n"); +} + +static void pcie_write_mrrs(struct pci_dev *dev, int mps) +{ + int rc, mrrs; + + if (pcie_bus_config == PCIE_BUS_PERFORMANCE) { + int dev_mpss = 128 << dev->pcie_mpss; + + /* For Max performance, the MRRS must be set to the largest + * supported value. However, it cannot be configured larger + * than the MPS the device or the bus can support. This assumes + * that the largest MRRS available on the device cannot be + * smaller than the device MPSS. + */ + mrrs = mps < dev_mpss ? mps : dev_mpss; + } else + /* In the "safe" case, configure the MRRS for fairness on the + * bus by making all devices have the same size + */ + mrrs = mps; + + + /* MRRS is a R/W register. Invalid values can be written, but a + * subsiquent read will verify if the value is acceptable or not. + * If the MRRS value provided is not acceptable (e.g., too large), + * shrink the value until it is acceptable to the HW. + */ + while (mrrs != pcie_get_readrq(dev) && mrrs >= 128) { + rc = pcie_set_readrq(dev, mrrs); + if (rc) + dev_err(&dev->dev, "Failed attempting to set the MRRS\n"); + + mrrs /= 2; + } +} + +static int pcie_bus_configure_set(struct pci_dev *dev, void *data) +{ + int mps = 128 << *(u8 *)data; + + if (!pci_is_pcie(dev)) + return 0; + + dev_info(&dev->dev, "Dev MPS %d MPSS %d MRRS %d\n", + pcie_get_mps(dev), 128<pcie_mpss, pcie_get_readrq(dev)); + + pcie_write_mps(dev, mps); + pcie_write_mrrs(dev, mps); + + dev_info(&dev->dev, "Dev MPS %d MPSS %d MRRS %d\n", + pcie_get_mps(dev), 128<pcie_mpss, pcie_get_readrq(dev)); + + return 0; +} + +/* pcie_bus_configure_mps requires that pci_walk_bus work in a top-down, + * parents then children fashion. If this changes, then this code will not + * work as designed. + */ +void pcie_bus_configure_settings(struct pci_bus *bus, u8 mpss) +{ + u8 smpss = mpss; + + if (!bus->self) + return; + + if (!pci_is_pcie(bus->self)) + return; + + if (pcie_bus_config == PCIE_BUS_SAFE) { + pcie_find_smpss(bus->self, &smpss); + pci_walk_bus(bus, pcie_find_smpss, &smpss); + } + + pcie_bus_configure_set(bus->self, &smpss); + pci_walk_bus(bus, pcie_bus_configure_set, &smpss); +} + unsigned int __devinit pci_scan_child_bus(struct pci_bus *bus) { unsigned int devfn, pass, max = bus->secondary; diff --git a/include/linux/pci.h b/include/linux/pci.h index f27893b3b72..1ff9bbafd93 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -251,7 +251,8 @@ struct pci_dev { u8 revision; /* PCI revision, low byte of class word */ u8 hdr_type; /* PCI header type (`multi' flag masked out) */ u8 pcie_cap; /* PCI-E capability offset */ - u8 pcie_type; /* PCI-E device/port type */ + u8 pcie_type:4; /* PCI-E device/port type */ + u8 pcie_mpss:3; /* PCI-E Max Payload Size Supported */ u8 rom_base_reg; /* which config register controls the ROM */ u8 pin; /* which interrupt pin this device uses */ @@ -617,6 +618,16 @@ struct pci_driver { /* these external functions are only available when PCI support is enabled */ #ifdef CONFIG_PCI +extern void pcie_bus_configure_settings(struct pci_bus *bus, u8 smpss); + +enum pcie_bus_config_types { + PCIE_BUS_PERFORMANCE, + PCIE_BUS_SAFE, + PCIE_BUS_PEER2PEER, +}; + +extern enum pcie_bus_config_types pcie_bus_config; + extern struct bus_type pci_bus_type; /* Do NOT directly access these two variables, unless you are arch specific pci @@ -796,6 +807,8 @@ int pcix_get_mmrbc(struct pci_dev *dev); int pcix_set_mmrbc(struct pci_dev *dev, int mmrbc); int pcie_get_readrq(struct pci_dev *dev); int pcie_set_readrq(struct pci_dev *dev, int rq); +int pcie_get_mps(struct pci_dev *dev); +int pcie_set_mps(struct pci_dev *dev, int mps); int __pci_reset_function(struct pci_dev *dev); int pci_reset_function(struct pci_dev *dev); void pci_update_resource(struct pci_dev *dev, int resno); -- cgit v1.2.3-70-g09d2 From 47c08f3107270e5a439bc0106a308f7c48c9621d Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Sat, 20 Aug 2011 11:49:43 -0700 Subject: pci: fix new kernel-doc warning in pci.c Fix new kernel-doc warning in pci.c: Warning(drivers/pci/pci.c:3259): No description found for parameter 'mps' Warning(drivers/pci/pci.c:3259): Excess function parameter 'rq' description in 'pcie_set_mps' Signed-off-by: Randy Dunlap Cc: Jesse Barnes Signed-off-by: Linus Torvalds --- drivers/pci/pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 466fad6e6ee..0ce67423a0a 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3250,7 +3250,7 @@ int pcie_get_mps(struct pci_dev *dev) /** * pcie_set_mps - set PCI Express maximum payload size * @dev: PCI device to query - * @rq: maximum payload size in bytes + * @mps: maximum payload size in bytes * valid values are 128, 256, 512, 1024, 2048, 4096 * * If possible sets maximum payload size -- cgit v1.2.3-70-g09d2 From ed2888e906b56769b4ffabb9c577190438aa68b8 Mon Sep 17 00:00:00 2001 From: Jon Mason Date: Thu, 8 Sep 2011 16:41:18 -0500 Subject: PCI: Remove MRRS modification from MPS setting code Modifying the Maximum Read Request Size to 0 (value of 128Bytes) has massive negative ramifications on some devices. Without knowing which devices have this issue, do not modify from the default value when walking the PCI-E bus in pcie_bus_safe mode. Also, make pcie_bus_safe the default procedure. Tested-by: Sven Schnelle Tested-by: Simon Kirby Tested-by: Stephen M. Cameron Reported-and-tested-by: Eric Dumazet Reported-and-tested-by: Niels Ole Salscheider References: https://bugzilla.kernel.org/show_bug.cgi?id=42162 Signed-off-by: Jon Mason Acked-by: Jesse Barnes Signed-off-by: Linus Torvalds --- drivers/pci/pci.c | 2 +- drivers/pci/probe.c | 41 ++++++++++++++++++++++------------------- 2 files changed, 23 insertions(+), 20 deletions(-) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 0ce67423a0a..4e84fd4a431 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -77,7 +77,7 @@ unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE; unsigned long pci_hotplug_io_size = DEFAULT_HOTPLUG_IO_SIZE; unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE; -enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_PERFORMANCE; +enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_SAFE; /* * The default CLS is used if arch didn't set CLS explicitly and not diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 0820fc1544e..b1187ff31d8 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1396,34 +1396,37 @@ static void pcie_write_mps(struct pci_dev *dev, int mps) static void pcie_write_mrrs(struct pci_dev *dev, int mps) { - int rc, mrrs; + int rc, mrrs, dev_mpss; - if (pcie_bus_config == PCIE_BUS_PERFORMANCE) { - int dev_mpss = 128 << dev->pcie_mpss; + /* In the "safe" case, do not configure the MRRS. There appear to be + * issues with setting MRRS to 0 on a number of devices. + */ - /* For Max performance, the MRRS must be set to the largest - * supported value. However, it cannot be configured larger - * than the MPS the device or the bus can support. This assumes - * that the largest MRRS available on the device cannot be - * smaller than the device MPSS. - */ - mrrs = mps < dev_mpss ? mps : dev_mpss; - } else - /* In the "safe" case, configure the MRRS for fairness on the - * bus by making all devices have the same size - */ - mrrs = mps; + if (pcie_bus_config != PCIE_BUS_PERFORMANCE) + return; + + dev_mpss = 128 << dev->pcie_mpss; + /* For Max performance, the MRRS must be set to the largest supported + * value. However, it cannot be configured larger than the MPS the + * device or the bus can support. This assumes that the largest MRRS + * available on the device cannot be smaller than the device MPSS. + */ + mrrs = min(mps, dev_mpss); /* MRRS is a R/W register. Invalid values can be written, but a - * subsiquent read will verify if the value is acceptable or not. + * subsequent read will verify if the value is acceptable or not. * If the MRRS value provided is not acceptable (e.g., too large), * shrink the value until it is acceptable to the HW. */ while (mrrs != pcie_get_readrq(dev) && mrrs >= 128) { + dev_warn(&dev->dev, "Attempting to modify the PCI-E MRRS value" + " to %d. If any issues are encountered, please try " + "running with pci=pcie_bus_safe\n", mrrs); rc = pcie_set_readrq(dev, mrrs); if (rc) - dev_err(&dev->dev, "Failed attempting to set the MRRS\n"); + dev_err(&dev->dev, + "Failed attempting to set the MRRS\n"); mrrs /= 2; } @@ -1436,13 +1439,13 @@ static int pcie_bus_configure_set(struct pci_dev *dev, void *data) if (!pci_is_pcie(dev)) return 0; - dev_info(&dev->dev, "Dev MPS %d MPSS %d MRRS %d\n", + dev_dbg(&dev->dev, "Dev MPS %d MPSS %d MRRS %d\n", pcie_get_mps(dev), 128<pcie_mpss, pcie_get_readrq(dev)); pcie_write_mps(dev, mps); pcie_write_mrrs(dev, mps); - dev_info(&dev->dev, "Dev MPS %d MPSS %d MRRS %d\n", + dev_dbg(&dev->dev, "Dev MPS %d MPSS %d MRRS %d\n", pcie_get_mps(dev), 128<pcie_mpss, pcie_get_readrq(dev)); return 0; -- cgit v1.2.3-70-g09d2