Enabling CONFIG_USB_TI_CPPI41_DMA and disabling CONFIG_MUSB_PIO_ONLY. about linux

[RobertCNelson]

'problems' are usb 'device' specific.. Normally we'd see issues with wifi usb devices plugged into the am335x..

So if your plan is to only plug into devices and use the usb gadget connection.. should be fine..

if you plan to use any random wifi device, it'll fail..

Regards,

[davenmccalla-diagraph]

That's what I was afraid you'd say. The [RTW_CMD_THREAD] just below [irq/195-musb-hd] in the screen shot above is a thread for rtl8723bu wifi dongle. That was with CONFIG_MUSB_PIO_ONLY enabled.

I've been running with CONFIG_USB_TI_CPPI41_DMA enabled for a day with no issues. If there is a potential issue, would I have seen it already? Or could it take days or weeks to show up?

I have seen these messages show up when I insert a USB flash drive with DMA enabled. Not sure if it's just a coincidence. The flash drive appears to be working.
[83639.724250] F2FS-fs (sda): Can't find valid F2FS filesystem in 1th superblock
[83639.739171] F2FS-fs (sda): Can't find valid F2FS filesystem in 2th superblock
[83639.752825] F2FS-fs (sda): Can't find valid F2FS filesystem in 1th superblock
[83639.762741] F2FS-fs (sda): Can't find valid F2FS filesystem in 2th superblock

[davenmccalla-diagraph]

Thank you for responding. The folks at TI believe that PIO only mode or CPPI41_DMA are "very stable" in v4.19 or greater. I'm in the process of upgrading from v4.4 to v5.10, so I will not enable DMA for v4.4 but will enable it in v5.10. Then I'll test v5.10 thoroughly to make sure it doesn't affect my specific WiFi dongle.