2009-11-06 22:30:17 mmc_spi problem!!!

miaolf miao (CHINA)

Message: 82143

hello everybody,I am using the bf533 board and the uClinux-dist-2009R1-RC6.The mmc_spi driver is ok,but I find it is a "full_duplex" and it do not use the DMA.The spi_bfin5xx.c code noted that "the hardware does not support full duplex DMA transfers". But if i want to use the DMA in this mode how can I do? Thank you!

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2009-11-06 22:35:35 Re: mmc_spi problem!!!

Mike Frysinger (UNITED STATES)

Message: 82144

the HRM isnt lying. you cant do full duplex w/DMA -- it's a hardware limitation. nothing in software can magically make broken hardware work.

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2009-11-06 23:00:41 Re: mmc_spi problem!!!

miaolf miao (CHINA)

Message: 82145

Thank you! if i want use the dma in the half duplex ,how can I do ?

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2009-11-06 23:41:27 Re: mmc_spi problem!!!

Mike Frysinger (UNITED STATES)

Message: 82146

use enable_dma in the platform resources

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2009-11-07 00:12:08 Re: mmc_spi problem!!!

jiuchuan tang (CHINA)

Message: 82147

Hi Mike

I am the colleague of miaolf.We have the save problem. I have set the enable_dma flag of bfin5xx_spi_master and mmc's bfin5xx_spi_chip to 1,and in the " bfin_spi_pump_transfers" funtion of the code spi_bfin5xx.c,I print the state of the dma and full_duplex,like this

----------------------------------------------------------------------------------------------------------------------------

* Try to map dma buffer and do a dma transfer. If successful use,

* different way to r/w according to the enable_dma settings and if

* we are not doing a full duplex transfer (since the hardware does

* not support full duplex DMA transfers).

printk("full_duplex:%d,drv_data->cur_chip->enable_dma:%d,drv_data->len:%d\n",full_duplex,drv_data->cur_chip->enable_dma,drv_data->len);

if (!full_duplex && drv_data->cur_chip->enable_dma

&& drv_data->len > 6) {

--------------------------------------------------------------------------------------------------------------------------

And the info while the kernel start is full_duplex:1,drv_data->cur_chip->enable_dma:1,drv_data->len:1 and so on

so I think the enable_dma flag I have set .If there is any other place to set enable_dma flag or I should change other place.

Thank you for you help

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2009-11-07 01:12:03 Re: mmc_spi problem!!!

Mike Frysinger (UNITED STATES)

Message: 82148

i dont know what you're asking. looks to me like you already have all the info necessary.

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2009-11-07 01:29:07 Re: mmc_spi problem!!!

jiuchuan tang (CHINA)

Message: 82149

Mike,

I want to use the dma transfer,but in the code ,the full_duplex value is 1,so the code will not run "doing dma transfer",I want to ask why my full_duplex is 1,and how can I use the DMA transfer.

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2009-11-07 02:27:37 Re: mmc_spi problem!!!

jiuchuan tang (CHINA)

Message: 82150

Mike

I want to use the DMA to transfer the mmc_spi data.But after I made the everything and the mmc is worked ok ,I found the debug info displayed that "doing IO transfer", so I look the code and find that the debug info is from the bfin_spi_pump_transfers funtion,and in the funtion the condition if (!full_duplex && drv_data->cur_chip->enable_dma&& drv_data->len > 6) is 0 ,so it run the IO transfer,not DMA transfer.And when I look into it ,I find the full_duplex 's value is 1,it make the driver doing IO transfer,Now,I want the mmc to doing DMA transfer,how can I do.Thank you!

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2009-11-07 08:22:17 Re: mmc_spi problem!!!

Mike Frysinger (UNITED STATES)

Message: 82180

if the SPI device needs/wants to do a full duplex SPI transaction, there's nothing you can do about it

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2009-11-08 21:23:03 Re: mmc_spi problem!!!

jiuchuan tang (CHINA)

Message: 82190

Thank you Mike

I have some question about the MMC_SPI

1.MMC_SPI surport DMA and it regist DMA succeed,why it's IO transfer not the DMA transfer in fact.

2. If the MMC_SPI can surport DMA transfer how can I do and how can I validate it? The half-duplex mode is ok,the hardware need which mode to surport DMA I can change the mode to surport the DMA, I want to use the DMA not the IO transfer

Thank you

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2009-11-08 21:33:06 Re: mmc_spi problem!!!

Yi Li (CHINA)

Message: 82192

jiuchuan,

You can enable debug messages in the spi driver and see the output - whether the SPI is using DMA or PIO.

-Yi

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2009-11-08 22:25:40 Re: mmc_spi problem!!!

Robin Getz (UNITED STATES)

Message: 82193