Messages in this thread Patch in this message | | | Date | Thu, 16 Jul 2015 15:13:38 -0400 | From | Murali Karicheri <> | Subject | Re: [PATCH v1] ARM: pci: add call to pcie_bus_configure_settings() |
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On 05/16/2015 10:02 AM, Bjorn Helgaas wrote: > On Wed, May 28, 2014 at 01:14:53PM -0400, Murali Karicheri wrote: >> Call pcie_bus_configure_settings on ARM, like for other platforms. >> pcie_bus_configure_settings makes sure the MPS across the bus is >> uniform and provides the ability to tune the MRSS and MPS to higher >> performance values. This is particularly important for embedded where >> there is no firmware to program these PCI-E settings for the OS. >> >> Signed-off-by: Murali Karicheri <m-karicheri2@ti.com> >> >> CC: Russell King <linux@arm.linux.org.uk> >> CC: Bjorn Helgaas <bhelgaas@google.com> >> CC: Arnd Bergmann <arnd@arndb.de> >> CC: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> >> CC: Santosh Shilimkar <santosh.shilimkar@ti.com> >> --- >> - Fixed comments against initial version >> arch/arm/kernel/bios32.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c >> index 16d43cd..17a26c1 100644 >> --- a/arch/arm/kernel/bios32.c >> +++ b/arch/arm/kernel/bios32.c >> @@ -545,6 +545,18 @@ void pci_common_init_dev(struct device *parent, struct hw_pci *hw) >> */ >> pci_bus_add_devices(bus); >> } >> + >> + list_for_each_entry(sys, &head, node) { >> + struct pci_bus *bus = sys->bus; >> + >> + /* Configure PCI Express settings */ >> + if (bus && !pci_has_flag(PCI_PROBE_ONLY)) { >> + struct pci_bus *child; >> + >> + list_for_each_entry(child, &bus->children, node) >> + pcie_bus_configure_settings(child); > > This patch (8b5742ad156d ("ARM/PCI: Call pcie_bus_configure_settings() to > set MPS")) has been upstream since v3.16-rc1, but I think we goofed. > > The MPS configuration should be done *before* pci_bus_add_devices(). After > pci_bus_add_devices(), drivers may be bound to devices, and the PCI core > shouldn't touch device configuration while a driver owns the device. > > Looking at the code, it seems like it would have been simpler to do this in > the existing loop: > > list_for_each_entry(sys, &head, node) { > struct pci_bus *bus = sys->bus; > > if (bus && !pci_has_flag(PCI_PROBE_ONLY)) { > pci_bus_size_bridges(bus); > pci_bus_assign_resources(bus); > list_for_each_entry(child, &bus->children, node) > pcie_bus_configure_settings(child); > } > > pci_bus_add_devices(bus); > } > > so maybe there's some reason I'm not aware of for not doing it that way?
Bjorn,
This one has escaped my radar and I found it recently while I was searching for something else. I can't recall why this was not done this way. However I have tried the below code on Keystone and it works fine.
diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c index fcbbbb1..17efde7 100644 --- a/arch/arm/kernel/bios32.c +++ b/arch/arm/kernel/bios32.c @@ -520,7 +520,8 @@ void pci_common_init_dev(struct device *parent, struct hw_pci *hw) list_for_each_entry(sys, &head, node) { struct pci_bus *bus = sys->bus;
- if (!pci_has_flag(PCI_PROBE_ONLY)) { + if (bus && !pci_has_flag(PCI_PROBE_ONLY)) { + struct pci_bus *child; /* * Size the bridge windows. */ @@ -530,25 +531,15 @@ void pci_common_init_dev(struct device *parent, struct hw_pci *hw) * Assign resources. */ pci_bus_assign_resources(bus); - }
+ list_for_each_entry(child, &bus->children, node) + pcie_bus_configure_settings(child); + } /* * Tell drivers about devices found. */ pci_bus_add_devices(bus); } - - list_for_each_entry(sys, &head, node) { - struct pci_bus *bus = sys->bus; - - /* Configure PCI Express settings */ - if (bus && !pci_has_flag(PCI_PROBE_ONLY)) { - struct pci_bus *child; - - list_for_each_entry(child, &bus->children, node) - pcie_bus_configure_settings(child); - } - } }
The SATA comes up fine and ahci is able to override the mrrs value as shown by the log below.
[ 1.581526] ahci 0001:01:00.0: limiting MRRS to 256 [ 1.586521] ahci 0001:01:00.0: AHCI 0001.0000 32 slots 2 ports 6 Gbps 0x3 impl SATA mode [ 1.594604] ahci 0001:01:00.0: flags: 64bit ncq sntf led only pmp fbs pio slum part sxs [ 1.603772] scsi host0: ahci [ 1.606976] scsi host1: ahci [ If you are fine, I can send a patch for this. Please confirm.
Murali
> >> + } >> + } >> } >> >> #ifndef CONFIG_PCI_HOST_ITE8152 >> -- >> 1.7.9.5 >>
-- Murali Karicheri Linux Kernel, Keystone
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