On Tue, Jun 3, 2008 at 12:27 PM, Gadiyar, Anand <gadiyar@xxxxxx> wrote: >> Hi folks, >> >> I am trying to enable the whole musb HS DMA code on Blackfin. But >> found the is no place to clean the DMA interrupt flag in musbhsdma.c. >> As a result, the irq always happens with the same DMA irq source. I >> add some code to clear the DMA interrupt. Did I miss something here? > > The DMA interrupt register is cleared on a read. I don't think you need > to explicitly clear it. > Maybe there some difference between Blackfin and OMAP implementation. >From the Datatsheet of BF54x, it said that: --- USB DMA Interrupt (USB_DMA_INTERRUPT) Register The USB_INTRTX register (see Figure 13-9) indicates which of the eight DMA master channels have a pending interrupt. When the status has been read by the processor core, the corresponding bit should have a 1 written to it by the software in order to clear the status. --- And without the clearing operation, the DMA irq handler will be called endless. Thanks -Bryan >> >> After enabling the musb HS DMA code for Blackfin, normal operation is >> OK for mount/umount U-disks. But when I tried to write large file to >> the U-DISK (such as 10Mbyte or 100Mbyte), speed is very slow and mush >> slower than PIO mode, IMO. >> Did you guy meet this issue before on OMAP? >> >> Thanks >> -Bryan > > - Anand > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
