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 _______________________________________________ Linuxppc-embedded mailing list [email protected] https://ozlabs.org/mailman/listinfo/linuxppc-embedded
