2008-05-28 05:10:19     SPIDEV CS problems

Document created by Aaronwu Employee on Aug 6, 2013
Version 1Show Document
  • View in full screen mode

2008-05-28 05:10:19     SPIDEV CS problems

Nico van Leeuwen (NETHERLANDS)

Message: 56338   


I have a problem with the spidev driver. I created two devices with different CS pin allocations in my board file.

My board is a BF533 stamp. The devices created by spidev in the /dev directory are:

spidev0.4 and spidev0.5. I use uclinux release 2008R1-RC2.


I've also created a simple program which opens both SPI devices, read from them and then close the devices.

When I run this program for the first time it's a success it first reads spidev0.4 and then spidev0.5, CS4 and CS5 are behaving normally. When I run the program for the second time the CS pins behave wrong. Even if I'm just reading from one device simultanously both CS pins are going low, then the MISO contains just garbage because both SPI devices (AD7467) are trying to answer at the same time.


Who of you have encountered the same problem, and I wish, solved it? I think it's just simple mistake on my side?


Best regards and thanks in advance,


Nico van Leeuwen






2008-05-28 11:11:18     Re: SPIDEV CS problems

Mike Frysinger (UNITED STATES)

Message: 56351   


RC2 is not the latest RC ... please use the latest and retest




2008-05-29 02:50:32     Re: SPIDEV CS problems

Nico van Leeuwen (NETHERLANDS)

Message: 56388   


Where can I find that the problems are solved in RC8? Switching to another distro brings risks for me, but if it is necessary it has to be done..




2008-05-29 16:47:43     Re: SPIDEV CS problems

Mike Frysinger (UNITED STATES)

Message: 56430   


we really dont keep track of the issues we fix in the branch beyond the SCM log.  you can compare the versions by hand and review the svn log.


i'd poiint out that upgrading from rc2 to rc8 is really quite trivial considering the only thing there are bug fixes, and that nothing before rc8 should have been used other than for testing as we never announced 2008R1 for release before that.




2008-05-30 03:31:08     Re: SPIDEV CS problems

Nico van Leeuwen (NETHERLANDS)

Message: 56448   


Thank you for help.

Next week I will try the SPIDEV driver in the RC8 release.




2008-06-02 07:17:14     Re: SPIDEV CS problems

Nico van Leeuwen (NETHERLANDS)

Message: 56560   


Tested it today with the RC8 release, still have the same problems with SPIDEV.


I need help on this, because SPI is useless for me now. I can't use the SPI ADC driver because it's designed for just one adc device, and SPIDEV won't help me out yet.


Anyone facing the same troubles?




2008-06-02 12:17:07     Re: SPIDEV CS problems

Mike Frysinger (UNITED STATES)

Message: 56574   


post the spi resources you've declared for the devices


try making sure the spi mode is the same for them




2008-06-02 13:42:42     Re: SPIDEV CS problems


Message: 56576   


Hi Nico.


I've had similar issues, the fix I'm currently using was posted in this forum a while ago and I'm shocked it hasn't made it to mainline yet.  SPI has been totally broken for me for a while.




I also had to add pull-up resistors on the CS lines as they went into open-drain state.  Which might mean that the above patch is incorrect.


Mike, any thoughts?  My spi devices are both mode 0 on a bf548.






2008-06-02 14:55:55     Re: SPIDEV CS problems

Mike Frysinger (UNITED STATES)

Message: 56580   


there is an open tracker item for the SPI maintainer to review




2008-06-05 05:31:38     Re: SPIDEV CS problems

Nico van Leeuwen (NETHERLANDS)

Message: 56727   


Thanks Rob you pointed me to the solution! I can confirm that those changes to the spi_bfin5xx work. I've monitored the CS with my oscilloscope.


CS is behaving normally now, I still have some problems with SPI but I believe that has nothing to do with CS.


I found out that the search engine here works bad, otherwise I should have found the same post as Rob pointed me to after ages of searching...


Anyway thank you all for helping me out!




Nico van Leeuwen