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