On Wed, 2007-08-08 at 19:50 -0500, Nathan Lynch wrote:
> 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.
>
> Remove the gratuitous reads from u3_agp_write_config,
> u3_ht_write_config, and u4_pcie_write_config.
>
> Signed-off-by: Nathan Lynch <[EMAIL PROTECTED]>
Acked-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
---
Thanks ! Care to fix powermac too ? :-)
Cheers,
Ben.
> ---
> arch/powerpc/platforms/maple/pci.c | 9 ---------
> 1 files changed, 0 insertions(+), 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;
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