fsldma seems to be buggy, noticed in loop mode

[Zhang Wei]

Hi, Sebastian

Could you please apply these two patches and test again?

http://lkml.org/lkml/2008/3/10/64
http://lkml.org/lkml/2008/3/13/36

Thanks!
Wei.

> -----Original Message-----
> From: Sebastian Siewior [mailto:linuxppc-embedded at ml.breakpoint.cc] 
> Sent: Thursday, March 13, 2008 2:04 AM
> To: linuxppc-embedded at ozlabs.org
> Cc: Zhang Wei
> Subject: fsldma seems to be buggy, noticed in loop mode
> 
> Hello,
> 
> I have a little kmod where I dma data from one place to another (can
> post it if someone wants to see it). It works in general according to
> memcmp :)
> 
> If I set the DAHE flag (DAHTS = 0, for one byte transfers) everything
> seems to work as well (I see only the last byte which has the correct
> value).
> Now if I change the destination address to my FIFO I get the requested
> transfer size plus some extra bytes. The extra bytes are looking like
> exactly the same DMA transfer once again. Then my FIFO overruns.
> Enabling some printks in the kernel gave me the following log:
> 
> |of-fsl-dma-channel e0021100.dma-channe: new link desc alloc df32a000
> |of-fsl-dma-channel e0021100.dma-channe: --memcpy issue--
> |of-fsl-dma-channel e0021100.dma-channe: Ch 0, LD 1f32a000
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 0: 00050000
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 1: 1f0be000
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 2: 00050000
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 3: 1f36c000
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 4: 00000000
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 5: 00000001
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 6: 00000100
> |of-fsl-dma-channel e0021100.dma-channe: LD offset 7: 00000000
> |of-fsl-dma-channel e0021100.dma-channe: ----------------
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: xfer LDs staring 
> from 0x000000001f32a000
> |of-fsl-dma-channel e0021100.dma-channe: chan completed_cookie = 1
> |of-fsl-dma-channel e0021100.dma-channe: link descriptor 
> df32a000 will be recycle.
> |of-fsl-dma-channel e0021100.dma-channe: chan completed_cookie = 1
> |of-fsl-dma-channel e0021100.dma-channe: chan completed_cookie = 1
> 
> done. 
> I have one list entry which is df32a000. According to the output that
> single request gets started a couple of times what would 
> explain why the
> FIFO overruns.
> Is it possible that the driver does not properly recognize that the
> transfer is finished _and_ that is the last one in line? Enabling the
> dma self test Kconfig option shows no error message but the number of
> interrupts that have been generated differ from channel to channel,
> from boot to boot.
> 
> btw: It is a MPC8544 DS with -rc5.
> 
> thanks,
>  Sebastian
>