Sitara Linux MUSB Issues

This page lists the known MUSB issues in the Linux SDK.

AMSDK 08.00.00.00

All the issues/patches in this section except #8.2 are applicable to AMSDK 07.00.00.00.

8.1. MUSB CPPI DMA driver does not handle TX Zero-Length Packet (ZLP).

Solution: Apply Bin Liu's patch [usb: musb: cppi41: fix not transmitting zero length packet issue]. This patch is available in mainline kernel v3.17.

8.2. USB device hotplug fails when connected behind a hub.

This issue does not exist in AMSDK 7.0 kernel.

Solution: Apply Bin Liu's patch [usb: musb: fix device hotplug behind hub]. This patch is available in mainline kernel v4.0-rc1.

8.3. Application frequently opening/closing the USB device could cause USB bus lockup.

The lockup will happen when tearing down a CPPI RX channel which another CPPI RX channel is receiving USB packets.

Solution: Apply the following Bin Liu's patches, which are available in mainline kernel v4.0-rc1.

a. [usb: musb: cppi41: correct the macro name EP_MODE_AUTOREG_*].

b. [usb: musb: cppi41: improve rx channel abort routine].

8.4. The driver does not drive the RESUME signal long enough which causes some hubs failed to resume.

Solution: Apply the following Felipe Balbi's patches, which will be available in mainline kernel v4.1-rc1.

a. [usb: define a generic USB_RESUME_TIMEOUT macro].

b. [usb: musb: use new USB_RESUME_TIMEOUT].

c. [usb: core: hub: use new USB_RESUME_TIMEOUT].

AMSDK 07.00.00.00

7.1. USB gadget driver is failed to load while it is built into the kernel image.

If a USB gadget driver is selected and built into the kernel along with MUSB drivers, the gadget driver initialization failed. The output of command 'cat /sys/class/udc/musb-hdrc.0.auto/uevent' does not show 'DRIVER=<xxx>'.

Solution: 'Manually' apply Ezequiel Garcia's patch [ARM: dts: am33xx: Move the cppi41dma node so it's probed early].

Please ensure all MUSB related drivers are not confiugered as module, or the gadget driver is unable to bind to UDC.

7.2. MUSB CPPI DMA driver does not handle RX Zero-Length Packet (ZLP).

Solution: Apply Daniel Mack's patch [dma: cppi41: handle 0-length packets].

7.3. Kernel crashes if unplug a USB device while a USB transfer is till active.

Solution: Apply the following Daniel Mack's patches, which are available in mainline kernel v3.14.

a. [usb: musb: use is_host_active() to distinguish between host and gadget mode].

b. [usb: musb: fix bit mask for CSR in musb_h_tx_flush_fifo()].

7.4. Fix RX short packet handling in host mode

Solution: Apply Daniel Mack's patch [usb: musb: introduce dma_channel.rx_packet_done]. This patch is available in mainline kernel v3.14.

7.5. Access incorrect endpoint CSR registers, which causes strange issues such as stream starvation.

Solution: Apply Daniel Mack's patch [usb: musb/cppi41: call musb_ep_select() before accessing an endpoint's CSR]. This patch is available in mainline kernel v3.14.

7.6. Fire hrtimer too late for pre-mature TX DMA completion interrupt for smaller packets.

Solution: Apply the following Daniel Mack's patchs, which are available in mainline kernel v3.14.

a. File:0001-Revert-usb-musb-musb cppi41-Handle-ISOCH-differently.patch.gz.

b. [usb: musb: cppi41: fire hrtimer according to programmed channel length].

7.7. In some cases the USB port is dead due to a USB PHY operation is following the PHY power on transition too quickly.

Solution: 'Manually' apply Daniel Mack's patch [usb: phy: am335x-control: wait 1ms after power-up transitions]. This patch is available in mainline kernel v3.14.

AMSDK 06.00.00.00

6.1. Patch to correct the CPPI DMA Queue assignments.

File:0001-usb-musb-cppi41-correct-the-assigned-free-queues-for.patch.gz

6.2. Zero-Length Packet status does not get updated when zlp packet received in grndis mode.

Solution: Apply patch File:0001-usb-musb-cppi41-zlp-rx-handling-in-generic-rndis-mod.patch.gz

6.3. The CPPI driver TX completion routine has a race condition in which the CPPI could lock up when tx-ep is still busy in transferring data and configuring the next request.

Solution: Apply patch File:0001-usb-cppi41-forcing-txdma-completion-at-polling-at-sc.patch.gz

6.4. The required zero-length packet (ZLP) is not transmitted when the TX packet size is multiple of EP packet size.

Solution: Apply patch File:0001-usb-musb-cppi41-transmit-ZLP-using-PIO.patch.gz [updated on 2015/11/04]

6.5. The CPPI DMA could lock up if a RX DMA channel is tearing down while another RX DMA channel is active receiving data packets.

Solution: Apply the following two patches.

6.5.1. File:0001-usb-cppi41-bypass-setting-rx-TD-bit-to-workaround-lo.patch.gz

6.5.2. File:0002-usb-cppi41-revised-rxdma-channel-teardown-sequence.patch.gz

6.6. The CPPI DMA could lock up in gadget mode due to tx-dma early completion issue in hardware.

Solution: Apply patch File:0001-usb-musb-cppi41-handle-tx-dma-early-completion-for-g.patch.gz

6.7. The CPPI driver TX completion routine has a bug which could cause a busy loop (100% CPU load) if a gadget driver pre-loads tx packet but the host does not receive it.

Solution: Apply patch File:0002-usb-musb-cppi41-fix-busy-loop-in-txdma completion wo.patch.gz

Archived

Sitara Linux SDK 08.00.00.00