AM3352 USB DMA issue

Michihito Kumai

Other Parts Discussed in Thread: AM3352

Hi,

I tried to connect a USB-WiFi device(AR9271) via USB HUB(USB2512B) to our AM3352
custom board. If the USB device put in heavy traffic condition, USB
host controller discontinued to send "IN token" to the device. I tried to
investigate this issue, I found a cause of issue in DMA driver. Our software engeneer modified DMA driver as follows, as a result USB host controller worked collectly even if the USB device put in heavy traffic condition. I think this modification may be resolve other USB DMA issue. Please let me know if any problem about this modification.

Best Regards,

Kumac

over 11 years ago

0 Biser Gatchev-XID over 11 years ago

TI__Guru**** 393215 points

Hi,

Which Linux version is this?

For details on how to submit patches please refer to this post: http://e2e.ti.com/support/arm/sitara_arm/f/791/t/400754

0 Michihito Kumai over 11 years ago in reply to Biser Gatchev-XID

Prodigy 90 points

Hi Biser,
Thank you for your support.
I used Linux kernel 3.14.34, and it is contained TI Linux kernel modification.

I try to explain about our driver modification.
- In the previous code, TX FIFO empty is checked in RX DMA complete condition, it is wrong.
- In the modified code, Do not check TX FIFO empty if DMA is RX DMA complete condition.

Best Regards,
kumac

0 Biser Gatchev-XID over 11 years ago in reply to Michihito Kumai

TI__Guru**** 393215 points

This forum supports only the TI distributed Linux SDK. The current version for AM335X is SDK 8.0, which is based on kernel 3.14.26.

0 Bin Liu over 11 years ago

TI__Guru**** 175491 points

Kumac,

I recommend you to post this patch to Linux USB mailing list - linux-usb@vger.kernel.org. Most kernel USB developers including the maintainer of this CPPI41 driver are on this list, they can provide comments about this change, and decide to pick this change to mainline kernel.

0 Michihito Kumai over 11 years ago in reply to Bin Liu

Prodigy 90 points

Hi Bin,

I posted this patch to Linux USB mailing list as following title.
"[PATCH] usb: musb: cppi41: fix condition to call cppi41_trans_done()."
I will discuss this patch on Linux mailing list after this.

Best Regards,
kumac

0 Bin Liu over 11 years ago in reply to Michihito Kumai

TI__Guru**** 175491 points

Kumac,

I noticed your patch on the mailing list too. Thanks for the contribution.

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AM3352 USB DMA issue