On Fri, Dec 14, 2012 at 6:11 PM, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> wrote: > On Fri, Dec 14, 2012 at 03:38:46PM +0000, Pawel Moll wrote: >> The Versatile Express IOFPGA as shipped on VECD 5.0 (bitfiles v108/208 >> and v116/216) contains a modified version of the PL180 MMCI, with >> PeriphID Configuration value changed to 0x2. >> >> This version adds an optional "hardware flow control" feature. When >> enabled MMC card clock will be automatically disabled when FIFO is >> about to over/underflow and re-enabled once the host retrieved some >> data. This makes the controller immune to over/underrun errors caused >> by big interrupt handling latencies. > > Wrong. It doesn't make it "immune", it just makes it less likely to > occur - you just need a heavier workload to provoke it. That'd be what just adding DMA would do (Pawel mentioned this being cooked for the Vexpress as well I think). Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
