Messages in this thread Patch in this message | | | Subject | [PATCH] pci-mmconfig fix for 2.6.9 | Date | Wed, 10 Nov 2004 22:56:45 +0530 | From | "Durairaj, Sundarapandian" <> |
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Here I have attached pci mmconfig fix for 2.6.9 kernel.
This will fix the flush error in pci_mmcfg_write.
When pci_mmcfg_write is used to program the PMCSR in the Power Management Capability structure of PCI config space in the PCI Express device to a different power state, the dummy readl to flush the previous write violates the transition delay specified in the PCI power management spec. Please see PCI Power Management Spec. 1.2 Table 5-6. For example, while changing the power state of the device through PMCSR register, a transition delay of 10msec is required before any access can be made to the device.
Since the configuration write access for PCI Express is non posted, flushing is not necessary and it will be safe to remove the dummy readl.
This patch will remove dummy readl function implemented in "pci_mmcfg_write" and use set_fixmap_nocahe instead of set_fixmap.
Thanks, Sundar
diff -Naur linux-2.6.9/arch/i386/pci/mmconfig.c pcie-fix-linux-2.6.9/arch/i386/pci/mmconfig.c --- linux-2.6.9/arch/i386/pci/mmconfig.c 2004-10-19 03:24:38.000000000 +0530 +++ pcie-fix-linux-2.6.9/arch/i386/pci/mmconfig.c 2004-11-04 11:35:36.029054848 +0530 @@ -30,7 +30,7 @@ u32 dev_base = pci_mmcfg_base_addr | (bus << 20) | (devfn << 12); if (dev_base != mmcfg_last_accessed_device) { mmcfg_last_accessed_device = dev_base; - set_fixmap(FIX_PCIE_MCFG, dev_base); + set_fixmap_nocache(FIX_PCIE_MCFG, dev_base); } } @@ -85,9 +85,6 @@ break; } - /* Dummy read to flush PCI write */ - readl(mmcfg_virt_addr); - spin_unlock_irqrestore(&pci_config_lock, flags); return 0; diff -Naur linux-2.6.9/arch/x86_64/pci/mmconfig.c pcie-fix-linux-2.6.9/arch/x86_64/pci/mmconfig.c --- linux-2.6.9/arch/x86_64/pci/mmconfig.c 2004-10-19 03:23:41.000000000 +0530 +++ pcie-fix-linux-2.6.9/arch/x86_64/pci/mmconfig.c 2004-11-04 11:39:21.989703608 +0530 @@ -63,9 +63,6 @@ break; } - /* Dummy read to flush PCI write */ - readl(addr); - return 0; }
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