Felipe Balbi wrote: > On Wed, May 12, 2010 at 05:19:36PM +0530, Ajay Kumar Gupta wrote: > > MUSB RTL version 1.4 has a hardware issue when TX and RX DMA channels are > > simultaneously enabled which results in DMA lockup. > > I've seen it on rtl1.8 also if I remember correctly. > I'm fairly certain that this is not the case with RTL1.8, and if it is I'm very much interested in getting to the bottom of it. Do you have a test case that reproduces the lockup? Or a description of your use-case, or a register dump at failure, or any other clues? > > Use system DMA for all RX channels as a workaround of this issue as this > > will have minimal throughput overhead based on the fact that Rx transfers > > are done in DMA mode-0 on OMAP34x/35x platforms. > > > > Another approach to use PIO mode in opposite direction would increase the > > cpu loading and thus using system DMA is preferred workaround. > > > > Signed-off-by: Anand Gadiyar <gadiyar@xxxxxx> > > Signed-off-by: Ajay Kumar Gupta <ajay.gupta@xxxxxx> > > I think falling back to pio is better than this patch. It will most > likely be only one transfer. Another approach is to allocate dma > channels on a transfer basis. This is way too big of a problem. Which one is better depends on how many endpoints are doing, transfers in parallel, I suppose. I did post the a patch for the other approach (to fall back to PIO). I haven't received a response to that yet. I'm okay with either approach. - Anand-- 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
