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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 <andre.schwarz@matrix-vision.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Andre Schwarz 2008-07-10 11:53:16 +02:00 committed by Grant Likely
parent 0db9360aaa
commit 6eb9d32298
1 changed files with 2 additions and 1 deletions
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3
arch/powerpc/platforms/52xx/mpc52xx_pci.c
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@ -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