2009-05-11 04:49:16     USB HC with DMA Support

Document created by Aaronwu Employee on Aug 15, 2013
Version 1Show Document
  • View in full screen mode

2009-05-11 04:49:16     USB HC with DMA Support

Harbhajan Singh (INDIA)

Message: 73938   

 

Hi,

 

Are there any external USB host controllers drivers available with DMA Support. Please tell us in which ezkit/stamp or any platform these are available.

 

Thankyou.

QuoteReplyEditDelete

 

 

2009-05-11 07:23:43     Re: USB HC with DMA Support

Wolfgang Muees (GERMANY)

Message: 73946   

 

Some USB controllers from NXP have DMA support, but you won't want it....

 

The only DMA support which makes sense for me for USB host controllers is busmaster DMA. Busmaster DMA is done in the PC world, and you have to search here. I think you will get some PCI chips here. So you need a Blackfin with PCI and Busmaster DMA capability.... good luck!

 

Non-busmaster DMA is useless because it's only a sort of memcopy inside the controller ISR. You will get no real computing time gains.

 

Best solution is to use a blackfin CPU with internal DMA for USB. You only have to wait about 5 years for analog devices to get their hardware up and running and adding the root hub.

 

regards

 

Wolfgang

TranslateQuoteReplyEditDelete

 

 

2009-05-11 15:38:35     Re: USB HC with DMA Support

Robin Getz (UNITED STATES)

Message: 73964   

 

Wolfgang:

 

>Non-busmaster DMA is useless.

 

This depends on the driver & pheripheral architecture. If the driver is architected in such a way that it can take advantage of a dma_memcpy type environment - then it is far from useless. It can allow the CPU to do other things while the pheripheral buffers are being dumped to main memory. It the peripheral memory is small, then it makes little sense. If it can buffer up things - then you can see good performance gains from it.

 

It also has secondary benifits (on a Blackfin) - interrupts do not need to be disabled when using DMA, like they do for a core read of ASYNC space.

 

-Robin

QuoteReplyEditDelete

 

 

2009-05-11 23:20:09     Re: USB HC with DMA Support

liang wang (CHINA)

Message: 73974   

 

Dear Robin:

 

If  do not use DMA,can the usb host OHCI  be realized in uclinux?If I use externel usb host IC ,but without DMA interface?

 

In the the field of hc_driver struct  in  drivers/usb/host

    .urb_enqueue =        ohci_urb_enqueue,

 

what is the effect of this function?

TranslateQuoteReplyEditDelete

 

 

2009-05-12 01:35:27     Re: USB HC with DMA Support

Harbhajan Singh (INDIA)

Message: 73977   

 

Hi,

 

Thankyou very much for the replies.

 

I need to know which ezkit/stamp or any platform has the usb host controller and it supports DMA mode.

 

I saw in the distribution "1362" host controller has the dma support, can anyone tell me which ezkit/stamp platform does this host controller exists.

 

Thankyou.

QuoteReplyEditDelete

 

 

2009-05-12 09:40:44     Re: USB HC with DMA Support

Harbhajan Singh (INDIA)

Message: 73993   

 

Hi,

 

I found the ISP1362 driver in the kernel platform where i could  BF537 stamp board with usb extender board.

 

Can anyone tell me whether this driver supports DMA mode or not?

 

Thankyou.

QuoteReplyEditDelete

 

 

2009-05-14 10:30:56     Re: USB HC with DMA Support

Harbhajan Singh (INDIA)

Message: 74070   

 

Hi,

 

Can anyone tell me whether the ISP1362 driver available in the distribution supports dma mode?

 

Thankyou all.

QuoteReplyEditDelete

 

 

2009-05-19 14:46:58     Re: USB HC with DMA Support

Robin Getz (UNITED STATES)

Message: 74280   

 

Harbhajan:

 

Go look in the source code.

 

-Robin

Attachments

    Outcomes