On Wed, 2018-09-05 at 14:08 +0000, Laurentiu Tudor wrote: > Hi Scott, > > > -----Original Message----- > > On Mon, 2018-08-27 at 20:15 +0200, Christian Zigotzky wrote: > > > Hello, > > > > > > Our users tested the RC1 of kernel 4.19 on their P5020 boards today. > > > Unfortunately the USB bug still exists. With mem values bigger than > > > > 4096M, > > > the USB mouse and keyboard doesn’t work. With the bootarg mem=4096M, the > > > > USB > > > devices work without any problems. Please compile the RC1 and test it on > > > your P5020 board. There is a problem with the memory management since > > > 22/08/18. > > > > I just tested 4.19-rc1 on a T4240 and got a similar problem with MMC. MMC > > and > > USB on these chips both have a 32-bit DMA limitation. I'll look into it. > > I encountered similar issues on LS104xA chips. This is the workaround for > MMC: > https://patchwork.kernel.org/patch/10506627/
That's not a workaround; it's the proper way to handle DMA addressing limits. > On the USB side I didn't find a proper place in the usb subsystem code for a > workaround but instead > found an undocumented kernel arg (*) that limits the dma mask to 32 bits: > xhci-hcd.quirks=0x800000. > > (*) https://patchwork.kernel.org/patch/10509159/ The mask should already be getting set to 32 bits. The problem is a recent patch that changed initcall order, which lead to swiotlb not being used. We need to rework the swiotlb notifier so it doesn't depend on initcall ordering. -Scott
