Arnd Bergmann <arnd@xxxxxxxx> writes: >> Anyway, I think readl()/writel() do the right thing: in BE mode they >> swap PCI accesses and don't swap normal registers, in LE mode nothing is >> swapped. > > This seems to be true when CONFIG_IXP4XX_INDIRECT_PCI is set, but > not otherwise. For the indirect variant, writel() is a __raw_writel() > without barrier or byteswap on non-PCI memory, while with that > option disabled, we use the standard implementation that has both > a byteswap and a barrier. > > According to your description, that would mean the version without > indirect PCI access is broken and it appears to have been that way > since before the start of git history in 2.6.12. > > It's possible that nobody cared because all drivers for non-PCI > devices on ixp4xx (the on chip ones) just use __raw_readl or > direct pointer references. Well, it is possible. I recall I probably used __raw_* instead of readl()/writel() in qmgr/npe/Ethernet drivers for this very reason. I think Direct pointer references are only used for locations in RAM (DMA buffers), they have their own share of problems because the peripherals are always big endian. I think I still have an early IXP425 board with UDC connector so I will try to dig it up and test this code. I wonder if we should switch the driver to use __raw_*, too. The problem is almost nobody uses UDC with this CPU. -- Krzysztof Halasa Industrial Research Institute for Automation and Measurements PIAP Al. Jerozolimskie 202, 02-486 Warsaw, Poland -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
