AM37x USB OTG Performance

Eugene,

I would recommend to use the latest driver available at (based on v2.6.34),

http://arago-project.org/git/people/?p=sriram/ti-psp-omap.git;a=shortlog;h=refs/heads/OMAPPSP_03.00.02.07

I hope you would have seen below details why this system DMA workaround is used for both 35x and 37x.

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          MUSB RTL version 1.4 (OMAP34x/35x) has a hardware issue when TX and RX
          DMA channels are simultaneously enabled. To work around this issue,
          you can choose to use System DMA for RX channels.

          Also on Mentor DMA in MUSB RTL version 1.8 (OMAP3630, AM/DM37x)
          requires buffers to be aligned on a four byte boundary. This affects
          USB CDC/RNDIS class application where buffers are always unaligned.
          To work around this issue, you can choose to use System DMA for
          unaligned buffers.

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As I understand you are using 35x on board with Revision D or below  (B or C) and 37x on the board with board revision of G. if so then

request you to please get the numbers for both 35x and 37x on board revision -G only. [you can just put the 35x processor card on Rev-G board]

Please find my response for your queries below.

>> 1. Why "Use System DMA for Mentor DMA workaround" flag has no effect on a newer board/cpu (AM37x-based)?

It should surely have the effect on 37x in improving the performance. would wait for further data on the latest tree with Rev-G board for both 35x and 37x.

>>2. What is the correct usage of the "Use System DMA for Mentor DMA workaround" parameter? Is it true that it should be turned ON for the OMAP35x and turned OFF for the >>AM37x?

It should be turned ON for both 35x and 37x. This is also the default settings.

>>3. Is it possible to turn "Use System DMA for Mentor DMA workaround" flag OFF for the OMAP35x and have reliable networking using Ethernet over USB (g_ether.ko gadget >>connected through USB OTG port to a PC host)?

Except the scenario of flood ping test case  where we have observed the MUSB lockup on 35x due to know hardware errata.

>>4. When slow performance of the USB OTG on the AM37x will be resolved? (5-6 MBytes/sec is very slow and is unacceptable).

System DMA workaround is suppose to be the solution for this. Please test with latest driver on Rev-G board.

Regards,
Ajay

Thank you, Ajay

My older board (OMAP35x) is the Rev.E board. Processor module says OMAP35XX RevC (P/N O3530-PB-S33-M2-0023)

My newer board (AM37X) is the Rev.G board.. Processor module says EVM 3530/3730 Processor Module Rev C. (P/N 0047000903-C-020)

Is it safe for me to put older processor module card onto my newer board or do the opposite?

Thank you,

Eugene.

Eugene,

Your processor module seems to be ES3.1 for omap35x and ES1.0 for 37x. Also as your are testing only OTG gadget mode so Rev-E board should be fine to capture

the numbers for 35x so no need to swap the board also. I would suggest you to capture the numbers once with latest tree I suggested.

Regards,
Ajay

Hi Ajay,

I am facing difficulties in enabling dedicated DMA for usb otg. I need to expose SDcard as mass storage through the HS USB OTG .

My setup is as follows

1. EVM MAIN BOARD REVG

2. EVM 3530/37XX Processor module RevD with AM3730 processor.

3. WINCE6.0 BSP version 6.15

After enabling USB DMA, Its taking long time to mount and only some files are copied in a 900 MB folder. This issue is not occurring in OMAP3530 where i can enable dma successfully.

i hope its is know issue since in Registry entry i have seen an entry like this "; DMA currently not working". Do have resolved this or any solution?

note: i found above comment in BSP_WINCE_ARM_A8_01_02_00 also

Regards

Jethin

Hi Ajay,

 I have found similar one issue which is mentioned in known issue

ID : SDOCM00075290

Jethin

Jethin,

Your issue is related to WinCE so request you to post the same to WinCE forum.

Regards,

Ajay