Device Driver problem

[Altera_Forum]

hello Guys, 

 I am new to Nios and uClinux  I have written a simple device driver for a nios custom peripheral   After configuring the peripheral ,through the driver, the peripheral writes result to on-chip memory ... but i am unable to read the new value of memory location from the application c code   However , i get the correct (updated) value if i read the memory location in the driver itself  If i write another application in c , just to read the particular memory location, and execute it after excuting the first application, the memory location shows the correct value  So please suggest a way(s) to read the updated memory cotents in the same application   Thanking in anticipation, Kunal

[Altera_Forum]

--- Quote Start ---  originally posted by kuni124d@Jun 29 2006, 12:53 PM hello guys,  i am new to nios and uclinux  i have written a simple device driver for a nios custom peripheral   after configuring the peripheral ,through the driver, the peripheral writes result to on-chip memory  ... but i am unable to read the new value of memory location from the application c code    however , i get the correct (updated) value if i read the memory location in the driver itself  if i write another application in c , just to read the particular memory location, and execute it after excuting the first application, the memory location shows the correct value  so please suggest a way(s) to read the updated memory cotents in the same application    thanking in anticipation, kunal <div align='right'><{post_snapback}> (index.php?act=findpost&pid=16532)  --- quote end ---    --- Quote End ---    This sounds like a cache issue. I would start looking there first.  Keith

[Altera_Forum]

set bit 31 of the memory address , ie | 0x80000000 , to uncache the access in both driver and user app.

[Altera_Forum]

--- Quote Start ---  originally posted by hippo@Jun 30 2006, 07:02 AM set bit 31 of the memory address , ie  | 0x80000000 , to uncache the access in both driver and user app. <div align='right'><{post_snapback}> (index.php?act=findpost&pid=16544)  --- quote end ---    --- Quote End ---    Thanx , i shall follow your instructions. But , the memory location is in "On- chip" memory , which I beleive is not cached. There could be some other problem

[Altera_Forum]

--- Quote Start ---  originally posted by kuni124d+jun 30 2006, 01:44 pm--><div class='quotetop'>quote (kuni124d @ jun 30 2006, 01:44 pm)</div>  --- quote start ---  <!--quotebegin-hippo@Jun 30 2006, 07:02 AM set bit 31 of the memory address , ie  | 0x80000000 , to uncache the access in both driver and user app. <div align='right'><{post_snapback}> (index.php?act=findpost&pid=16544)  --- quote end ---    --- Quote End ---    Thanx , i shall follow your instructions. But , the memory location is in "On- chip" memory , which I beleive is not cached. There could be some other problem <div align='right'><{post_snapback}> (index.php?act=findpost&pid=16553)</div> [/b]  --- Quote End ---   Why do you mean the onchip memory is not cached? If you have d-cache in nios2, everything is cached unless you turn on bit31 of the address or use IORW macro .

[Altera_Forum]

TO_BE_DONE

[Altera_Forum]

TO_BE_DONE

[Altera_Forum]

add "volatile" to your variable. 

eg volatile int data;