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Trying to clear PIO_START register when it is non-zero (which indicates that previous PIO transfer has not finished yet) causes an External Abort with SError 0xbf000002. This bug is currently worked around in TF-A by handling External Aborts in EL3 and ignoring this particular SError. This workaround was also discussed at: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=3c7dcdac5c50 https://lore.kernel.org/linux-pci/20190316161243.29517-1-repk@triplefau.lt/ https://lore.kernel.org/linux-pci/971be151d24312cc533989a64bd454b4@www.loen.fr/ https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/1541 Implement a proper fix to prevent this External Abort. As it is not possible to cancel a pending PIO transfer, simply do not start a new one if previous has not finished yet. In this case return an error to the caller. In most cases this SError happens when there is no PCIe card connected or when PCIe link is down. The reason is that in these cases a PIO transfer takes about 1.44 seconds. For this reason we also increase the wait timeout in pcie_advk_wait_pio() to 1.5 seconds. If PIO read transfer for PCI_VENDOR_ID register times out, or if it isn't possible to read it yet because previous transfer is not finished, return Completion Retry Status value instead of failing, to give the caller a chance to send a new read request. Signed-off-by: Pali Rohár <pali@kernel.org> Reviewed-by: Marek Behún <marek.behun@nic.cz> Reviewed-by: Stefan Roese <sr@denx.de>
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