[coreboot] [PATCH] SB700: enable PrefetchEnSPIFromHost to improve boot time from SPI flash

Stefan Reinauer stefan.reinauer at coresystems.de
Mon Oct 18 04:18:50 CEST 2010


 On 10/17/10 6:49 PM, Scott Duplichan wrote:
> This patch enables SB700 option PrefetchEnSPIFromHost in early setup.
> It affects only systems booting from SPI flash, not those booting from
> LPC flash. By default, the SB700 reads dwords from the SPI flash chip.
> Setting PrefetchEnSPIFromHost causes the SB700 to read entire cache
> lines from the flash chip. 
>
> Thanks,
> Scott
>
> Signed-off-by: Scott Duplichan <scott at notabs.org>

Acked-by: Stefan Reinauer <stepan at coreboot.org>
> Index: src/southbridge/amd/sb700/sb700_early_setup.c
> ===================================================================
> --- src/southbridge/amd/sb700/sb700_early_setup.c       (revision 5964)
> +++ src/southbridge/amd/sb700/sb700_early_setup.c       (working copy)
> @@ -129,6 +129,11 @@
>         reg8 |= (1 << 5) | (1 << 6);
>         pci_write_config8(dev, 0x47, reg8);
>
> +       /* Enable PrefetchEnSPIFromHost to speed up SPI flash read (does not affect LPC) */
> +       reg8 = pci_read_config8(dev, 0xbb);
> +       reg8 |= 1 << 0;
> +       pci_write_config8(dev, 0xbb, reg8);
> +
>         /* SuperIO, LPC ROM */
>         reg8 = pci_read_config8(dev, 0x48);
>         /* Decode ports 0x2e-0x2f, 0x4e-0x4f (SuperI/O configuration) */
>
>
>





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