On Thu, 30 Aug 2007 10:33:28 +0200 Stefan Roese <[EMAIL PROTECTED]> wrote:
> Problem Description and Fix : Memory Read Multiples(MRM) do not work > correctly on PPC 440EPX based systems. A PCI driver determines whether > MRMs are supported by reading the PCI cache line size register. If this > value is zero then MRMs are not supported. However some PCI drivers > write to the PCI cache line size register on initialization. This > results in MRMs being sent to system memory on 440EPX based systems. > Since MRMs do not work correctly in 440EPX based systems this may cause > system hang. This patch solves this problem by modifying the PPC > platform specific PCI configuration register write function, by forcing > any value written to PCI_CACHE_LINE_SIZE register to be 0. This fix was > tested on different PCI cards : i.e. Silicon Image ATA card and Intel > E1000 GIGE card. On Silicon Image ATA card without this fix in place > creating a filesystem on IDE drive "mke2fs /dev/hda" was hanging the > system. MRMs issued by the PCI card were seen on the PCI analyzer since > the Silicon Image driver was setting the PCI_CACHE_LINE_SIZE register to > 255. With this patch the PCI_CACHE_LINE_SIZE register was 0 and only > Memory Reads were seen on PCI analyzer. > > Signed-off-by: Pravin M. Bathija <[EMAIL PROTECTED]> > Signed-off-by: Stefan Roese <[EMAIL PROTECTED]> > > --- > I know this patch is a little "dirty", but perhaps somebody has a better > idea to fix this problem. Thanks. For the peanut gallery, Stefan and I discussed this a bit on IRC today and a different approach for arch/powerpc is going to be looked at instead. Namely, introducing a new flag for indirect_type in the pci_controller structure to key off of instead of having ifdefs. josh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
