Using GPMI-NAND driver on iMX28 using 3.4-rc1?

[Sam Gandhi]

Vinod,

On Thu, Apr 5, 2012 at 5:27 AM, Vinod Koul <vinod.koul at linux.intel.com> wrote:
> On Thu, 2012-04-05 at 05:03 -0700, Sam Gandhi wrote:
>> 2012/4/4 Huang Shijie <b32955 at freescale.com>:
>> > Hi All:
>> >> On Wed, Apr 4, 2012 at 7:07 PM, Sam Gandhi<samgandhi9 at gmail.com>  wrote:
>> >>
>> >>> I reverted that commit and I still see following  error!
>> >> Huang,
>> >>
>> >> Are you able to use gpmi on mx28 running 3.4-rc1?
>> >>
>> > I also meet the same problem today.
>> >
>> >
>> >>> flash_erase /dev/mtd1 0 0
>> >>> Erasing 1------------[ cut here ]------------
>> >>> kernel BUG at /home/sam/linux/drivers/dma/dmaengine.h:53!
>> > the mxs-dma has added some patches about the cookie.
>> > The bug is in the dmaengine.h.
>> >
>> > So let more people know this bug.
>> >
>> > BR
>> > Huang Shijie
>> >
>> >
>> FWIW, Just a data point.
>>
>> I coverted BUG_ON in dmaengine.h to printk as shown below. With this
>> change I was able to format nand, create UBI partition. I have been
>> running UBI torture test called integck on my board that does lot of
>> I/O, mounting/unmounting of filesystem for close to 8 hour now without
>> crash. But I do see those printks. I haven't followed logic of
>> tx->cookie well enough to figure out what the appropriate change
>> should be. Note this is with commit
>> 00292bbf769620dea923dbd906afd88955f7ea19 reverted in my tree.
>>
>> Cookie 0  completed 102118268 DMA_MIN 1
>> Cookie 0  completed 102120401 DMA_MIN 1
>> Cookie 0  completed 102237726 DMA_MIN 1
>>
>> git diff drivers/dma/dmaengine.h
>> diff --git a/drivers/dma/dmaengine.h b/drivers/dma/dmaengine.h
>> index 17f983a..3d10a70 100644
>> --- a/drivers/dma/dmaengine.h
>> +++ b/drivers/dma/dmaengine.h
>> @@ -50,7 +50,11 @@ static inline dma_cookie_t dma_cookie_assign(struct
>> dma_async_tx_descriptor *tx)
>>   */
>>  static inline void dma_cookie_complete(struct dma_async_tx_descriptor *tx)
>>  {
>> -       BUG_ON(tx->cookie < DMA_MIN_COOKIE);
>> +       if ( tx->cookie < DMA_MIN_COOKIE)
>> +               printk(KERN_ERR "Cookie %d,  completed %d DMA_MIN %d
>> ",tx->cookie,
>> +               tx->chan->completed_cookie,
>> +               DMA_MIN_COOKIE);
>> +       /* BUG_ON(tx->cookie < DMA_MIN_COOKIE); */
>>         tx->chan->completed_cookie = tx->cookie;
>>         tx->cookie = 0;
>>  }
> This means you are trying to mark a cookie complete when it is already
> marked so!, hence dmaengine screams.
> The bug is is mxs-dma.
> Let me know if below fixes it (assuming you are not using cyclic API,
> that would need fixup as well)
>
> diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
> index c81ef7e..5ddd84e 100644
> --- a/drivers/dma/mxs-dma.c
> +++ b/drivers/dma/mxs-dma.c
> @@ -399,6 +399,10 @@ static struct dma_async_tx_descriptor
> *mxs_dma_prep_slave_sg(
>                ccw->bits &= ~CCW_DEC_SEM;
>        } else {
>                idx = 0;
> +               /* assign cookie here,
> +                * hopefully for above case we dont need it
> +                */
> +               dma_cookie_assign(&mxs_chan->desc);
>        }
>
>        if (direction == DMA_TRANS_NONE) {
>
I applied your suggested change and don't hit the BUG_ON in
dmaengine.h with this change UBI torture test has run for last 30 min
or so I will let it run for a day. [ I will let mxs-dma authors
comment if this is a right change.. ]

-Sam