From: Andre Schwarz Date: Thu, 10 Jul 2008 09:53:16 +0000 (+0200) Subject: powerpc/mpc5200: PCI write combine timer X-Git-Tag: v2.6.27-rc1~1058^2~13^2~13 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=6eb9d32298290b956693fd85c815b817d39a9505;p=linux-2.6-omap-h63xx.git powerpc/mpc5200: PCI write combine timer On MPC5200 the PCI target control register (PCITCR) @ MBAR + 0xD6C is initialized with only bit 7 (Latrule disable) set. The 8-Bit write combine timer (Bits 24..31) should be also set to a reasonable value _greater zero_ (0x08 = default) since setting it to 0x00 leads to _very poor_ performance as a PCI target since external burst won't be possible at all. Setting the WCT to 0x08 (cache-line size) leads to good overall perfomance. Signed-off-by: Andre Schwarz Signed-off-by: Grant Likely --- diff --git a/arch/powerpc/platforms/52xx/mpc52xx_pci.c b/arch/powerpc/platforms/52xx/mpc52xx_pci.c index e3428ddd904..5a382bb15f6 100644 --- a/arch/powerpc/platforms/52xx/mpc52xx_pci.c +++ b/arch/powerpc/platforms/52xx/mpc52xx_pci.c @@ -63,6 +63,7 @@ #define MPC52xx_PCI_TCR_P 0x01000000 #define MPC52xx_PCI_TCR_LD 0x00010000 +#define MPC52xx_PCI_TCR_WCT8 0x00000008 #define MPC52xx_PCI_TBATR_DISABLE 0x0 #define MPC52xx_PCI_TBATR_ENABLE 0x1 @@ -313,7 +314,7 @@ mpc52xx_pci_setup(struct pci_controller *hose, out_be32(&pci_regs->tbatr1, MPC52xx_PCI_TBATR_ENABLE | MPC52xx_PCI_TARGET_MEM ); - out_be32(&pci_regs->tcr, MPC52xx_PCI_TCR_LD); + out_be32(&pci_regs->tcr, MPC52xx_PCI_TCR_LD | MPC52xx_PCI_TCR_WCT8); tmp = in_be32(&pci_regs->gscr); #if 0