On Fri, Nov 23, 2018 at 12:24:26AM +0200, Aaro Koskinen wrote: > Hi, > > On Thu, Nov 22, 2018 at 03:12:36PM +0000, Russell King - ARM Linux wrote: > > On Thu, Nov 22, 2018 at 10:29:48AM +0000, Russell King - ARM Linux wrote: > > > On Tue, Nov 20, 2018 at 11:04:06PM +0200, Aaro Koskinen wrote: > > > > I had switched to PIO mode in 2015 since the WARNs about legacy DMA > > > > API were too annoying and flooding the console. And now that I tried > > > > using DMA again with g_ether, it doesn't work anymore. The device get's > > > > recognized on host side, but no traffic goes through. Switching back to > > > > PIO makes it to work again. > > > > > > A solution to that would be to do what the warning message says, and > > > update the driver to the DMAengine API. > > Fully agreed, but I was busy debugging other more serious issues, and > just wanted to get a reliable ssh or USB serial access to the device > without any extra noise, so switching to PIO using a module parameter > is probably what most users do in such situations. > > > Here's a partial conversion (not even build tested) - it only supports > > OUT transfers with dmaengine at the moment. > > Thanks, I'll take a closer look and try to do some testing hopefully > during the weekend.
The patch was more for Peter to take a peek at - there's definitely some bits missing in the dmaengine driver (like the write to the LCH_CTRL register) that would need to be fixed somehow. However, it's worth noting that there is exactly one user of omap_set_dma_channel_mode(), which is omap-udc, which means any DMA channel made use of by omap-udc will have the LCH_CTRL register modified to LCH_P, and it will remain that way even if someone else subsequently makes use of the same channel. That's rather suspicious to me... maybe we can just initialise all LCH_CTRL registers to LCH_P in the dmaengine driver in that case! If not, then there's a bug right there. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
