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authorLinus Walleij <linus.walleij@linaro.org>2011-07-01 16:47:28 +0200
committerVinod Koul <vinod.koul@intel.com>2011-07-14 04:56:59 +0530
commitb89243dd0e6a1c96a4a346cb3e1ba2c637cdfe98 (patch)
tree44cf691c79d5ce229ec0afe76d04ebd438c1576e /drivers/dma
parent98ca528916c47ad17f78a07b45e49de3940fba77 (diff)
downloadlinux-b89243dd0e6a1c96a4a346cb3e1ba2c637cdfe98.tar.bz2
dmaengine/coh901318: fix slave submission semantics
While testing Per Forlins MMC speed improvements I noticed a semantic bug in the COH901318 driver: it will write to channel registers in the prep_slave_sg() function, instead of deferring it to later, breaking the assumption from the drivers to be able to queue up new jobs while another job is running. Fix this by storing up the initial register writes in the job descriptors and write them to hardware when we process the descriptor instead. Now the stress tests work. Acked-by: Per Forlin <per.forlin@linaro.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/coh901318.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
index af8c0b5ed70f..a7fca1653933 100644
--- a/drivers/dma/coh901318.c
+++ b/drivers/dma/coh901318.c
@@ -40,6 +40,8 @@ struct coh901318_desc {
struct coh901318_lli *lli;
enum dma_data_direction dir;
unsigned long flags;
+ u32 head_config;
+ u32 head_ctrl;
};
struct coh901318_base {
@@ -660,6 +662,9 @@ static struct coh901318_desc *coh901318_queue_start(struct coh901318_chan *cohc)
coh901318_desc_submit(cohc, cohd);
+ /* Program the transaction head */
+ coh901318_set_conf(cohc, cohd->head_config);
+ coh901318_set_ctrl(cohc, cohd->head_ctrl);
coh901318_prep_linked_list(cohc, cohd->lli);
/* start dma job on this channel */
@@ -1090,8 +1095,6 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
} else
goto err_direction;
- coh901318_set_conf(cohc, config);
-
/* The dma only supports transmitting packages up to
* MAX_DMA_PACKET_SIZE. Calculate to total number of
* dma elemts required to send the entire sg list
@@ -1128,16 +1131,18 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
if (ret)
goto err_lli_fill;
- /*
- * Set the default ctrl for the channel to the one from the lli,
- * things may have changed due to odd buffer alignment etc.
- */
- coh901318_set_ctrl(cohc, lli->control);
COH_DBG(coh901318_list_print(cohc, lli));
/* Pick a descriptor to handle this transfer */
cohd = coh901318_desc_get(cohc);
+ cohd->head_config = config;
+ /*
+ * Set the default head ctrl for the channel to the one from the
+ * lli, things may have changed due to odd buffer alignment
+ * etc.
+ */
+ cohd->head_ctrl = lli->control;
cohd->dir = direction;
cohd->flags = flags;
cohd->desc.tx_submit = coh901318_tx_submit;