From 1bdb2867e5f0bca7c94f7df92f23fdd20524a488 Mon Sep 17 00:00:00 2001 From: Nathan Lynch Date: Thu, 9 Aug 2007 10:50:44 +1000 Subject: [PATCH] [POWERPC] Remove gratuitous reads from maple PCI config space methods The maple PCI configuration space write methods read the written location immediately after the write is performed, presumably in order to flush the write. However, configuration space writes are not allowed to be posted, making these reads gratuitous. Furthermore, this behavior potentially causes us to violate the PCI PM spec when changing between e.g. D0 and D3 states, because a delay of up to 10ms may be required before the OS accesses configuration space after the write which initiates the transition. It definitely causes a system hang for me with a Broadcom 5721 PCIE network adapter, which is fixed by this change. Therefore this removes the gratuitous reads from u3_agp_write_config, u3_ht_write_config, and u4_pcie_write_config. Signed-off-by: Nathan Lynch Acked-by: Benjamin Herrenschmidt Signed-off-by: Paul Mackerras --- arch/powerpc/platforms/maple/pci.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/arch/powerpc/platforms/maple/pci.c b/arch/powerpc/platforms/maple/pci.c index 2542403..b095eaa 100644 --- a/arch/powerpc/platforms/maple/pci.c +++ b/arch/powerpc/platforms/maple/pci.c @@ -169,15 +169,12 @@ static int u3_agp_write_config(struct pci_bus *bus, unsigned int devfn, switch (len) { case 1: out_8(addr, val); - (void) in_8(addr); break; case 2: out_le16(addr, val); - (void) in_le16(addr); break; default: out_le32(addr, val); - (void) in_le32(addr); break; } return PCIBIOS_SUCCESSFUL; @@ -268,15 +265,12 @@ static int u3_ht_write_config(struct pci_bus *bus, unsigned int devfn, switch (len) { case 1: out_8(addr, val); - (void) in_8(addr); break; case 2: out_le16(addr, val); - (void) in_le16(addr); break; default: out_le32(addr, val); - (void) in_le32(addr); break; } return PCIBIOS_SUCCESSFUL; @@ -376,15 +370,12 @@ static int u4_pcie_write_config(struct pci_bus *bus, unsigned int devfn, switch (len) { case 1: out_8(addr, val); - (void) in_8(addr); break; case 2: out_le16(addr, val); - (void) in_le16(addr); break; default: out_le32(addr, val); - (void) in_le32(addr); break; } return PCIBIOS_SUCCESSFUL; -- 2.7.4