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

[Sam Gandhi <samgandhi9@xxxxxxxxx>]

>
>
> It's maybe too late to assign the DMA cookie after mxs_dma_enable_chan() in
> mxs_dma_tx_submit().
> The interrupt may arise before the dma_cookie_assign() finishes.
>
> Why mmc/audio do not have this bug? their interrupt arise too slow.
>
> I tested the following code :
> ==============================================================
>
> diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
> index 5978113..0f5b09a 100644
> --- a/drivers/dma/mxs-dma.c
> +++ b/drivers/dma/mxs-dma.c
> @@ -202,10 +202,12 @@ static struct mxs_dma_chan *to_mxs_dma_chan(struct
> dma_cha
> static dma_cookie_t mxs_dma_tx_submit(struct dma_async_tx_descriptor *tx)
> {
> struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(tx->chan);
> + dma_cookie_t c;
>
> + c = dma_cookie_assign(tx);
> mxs_dma_enable_chan(mxs_chan);
>
> - return dma_cookie_assign(tx);
> + return c;
> }
>
If this is the issue, then why not have mxs_dma_enable_chan itself
call dma_cookie_assign() and return that cookie.

That way mxs_dma_enable_chan() is self contained function that assign
the cookie, enables channel and returns assigned cookie. And nobody
will make mistake of calling just mxs_dma_enable_chan without first
calling dma_cookie_assign?

-Sam

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