From 2a926e46022ad7a03e0ac167d8c2b0d88c12c5a8 Mon Sep 17 00:00:00 2001 From: Russell King - ARM Linux Date: Tue, 6 Mar 2012 22:36:07 +0000 Subject: dmaengine: fix cookie handling in iop-adma.c and ppc4xx/adma.c MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Dan Williams said: > > Russell King wrote: > > Firstly, we have DMA_MIN_COOKIE which has value 1 - so any cookies below > > that aren't valid.  That seems sane. > > > > We seem to have different behaviours: > > > > -       cookie = c->cookie; > > -       cookie++; > > -       if (cookie < 0) > > -               cookie = 1; > > -       c->cookie = cookie; > > -       tx->cookie = cookie; > > > > c->cookie here is initialized to zero, so the first cookie given out will > > be 1.  This is how most DMA engine drivers implement this. > > > > Then we have this: > > > >                cookie = chan->common.cookie; > >                cookie++; > >                if (cookie <= 1) > >                        cookie = 2; > > > >                /* initialize the completed cookie to be less than > >                 * the most recently used cookie > >                 */ > >                chan->common.completed_cookie = cookie - 1; > >                chan->common.cookie = sw_desc->async_tx.cookie = cookie; > > > > Again, chan->common.cookie starts off at 0.  The first cookie given out > > will be 2, and 1 will never be used.  There are three drivers which > > implement it this way. > > > > Why is there this difference, and can these three be corrected to behave > > the same way as the first (and therefore the assignment of cookies > > consolidated?) > > Yes, they should be consolidated, and I believe they have drifted only > because there were no good common helpers and murphy's law took over. So lets fix this up to use the common dma_cookie_assign() helper. Signed-off-by: Russell King Tested-by: Linus Walleij Reviewed-by: Linus Walleij Acked-by: Jassi Brar [imx-sdma.c & mxs-dma.c] Tested-by: Shawn Guo Signed-off-by: Vinod Koul --- drivers/dma/iop-adma.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) (limited to 'drivers/dma/iop-adma.c') diff --git a/drivers/dma/iop-adma.c b/drivers/dma/iop-adma.c index b1e3be089c52..4370b1015f73 100644 --- a/drivers/dma/iop-adma.c +++ b/drivers/dma/iop-adma.c @@ -1622,16 +1622,12 @@ static void iop_chan_start_null_memcpy(struct iop_adma_chan *iop_chan) iop_desc_set_dest_addr(grp_start, iop_chan, 0); iop_desc_set_memcpy_src_addr(grp_start, 0); - cookie = iop_chan->common.cookie; - cookie++; - if (cookie <= 1) - cookie = 2; + cookie = dma_cookie_assign(&sw_desc->async_tx); /* initialize the completed cookie to be less than * the most recently used cookie */ iop_chan->common.completed_cookie = cookie - 1; - iop_chan->common.cookie = sw_desc->async_tx.cookie = cookie; /* channel should not be busy */ BUG_ON(iop_chan_is_busy(iop_chan)); @@ -1679,16 +1675,12 @@ static void iop_chan_start_null_xor(struct iop_adma_chan *iop_chan) iop_desc_set_xor_src_addr(grp_start, 0, 0); iop_desc_set_xor_src_addr(grp_start, 1, 0); - cookie = iop_chan->common.cookie; - cookie++; - if (cookie <= 1) - cookie = 2; + cookie = dma_cookie_assign(&sw_desc->async_tx); /* initialize the completed cookie to be less than * the most recently used cookie */ iop_chan->common.completed_cookie = cookie - 1; - iop_chan->common.cookie = sw_desc->async_tx.cookie = cookie; /* channel should not be busy */ BUG_ON(iop_chan_is_busy(iop_chan)); -- cgit v1.2.3