• Josh Boyer's avatar
    powerpc/4xx: Workaround for PPC440EPx/GRx PCI_28 Errata · 5ce4b596
    Josh Boyer authored
    The 440EPx/GRx chips don't support PCI MRM commands.  Drivers determine this
    by looking for a zero value in the PCI cache line size register.  However,
    some drivers write to this register upon initialization.  This can cause
    MRMs to be used on these chips, which may cause deadlocks on PLB4.
    
    The workaround implemented here introduces a new indirect_type flag, called
    PPC_INDIRECT_TYPE_BROKEN_MRM.  This is set in the pci_controller structure in
    the pci fixup function for 4xx PCI bridges by determining if the bridge is
    compatible with 440EPx/GRx.  The flag is checked in the indirect_write_config
    function, and forces any writes to the PCI_CACHE_LINE_SIZE register to be
    zero, which will disable MRMs for these chips.
    
    A similar workaround has been tested by AMCC on various PCI cards, such as
    the Silicon Image ATA card and Intel E1000 GIGE card.  Hangs were seen with
    the Silicon Image card, and MRMs were seen on the bus with a PCI analyzer.
    With the workaround in place, the card functioned properly and only Memory
    Reads were seen on the bus with the analyzer.
    Acked-by: default avatarStefan Roese <sr@denx.de>
    Signed-off-by: default avatarJosh Boyer <jwboyer@linux.vnet.ibm.com>
    5ce4b596
pci-bridge.h 9.15 KB