summaryrefslogtreecommitdiff
path: root/drivers/dma
diff options
context:
space:
mode:
authorRabin Vincent <rabin.vincent@stericsson.com>2012-05-17 13:47:38 +0530
committerFabio Baltieri <fabio.baltieri@linaro.org>2013-01-14 10:50:37 +0100
commitccc3d6976433aa67131117fccd2b5143d82a6f48 (patch)
tree5ef904efcb61988c273f4987cd2bc86c772cdec9 /drivers/dma
parent42365cf0fa19473dde5fe226b0e7e9ab8ea18af8 (diff)
downloadlinux-ccc3d6976433aa67131117fccd2b5143d82a6f48.tar.gz
dmaengine: ste_dma40: don't allow high priority dest event lines
Hardware bug: when a logical channel is triggerred by a high priority destination event line, an extra packet transaction is generated in case of important data write response latency on previous logical channel A and if the source transfer of current logical channel B is already completed and if no other channel with a higher priority than B is waiting for execution. Software workaround: do not set the high priority level for the destination event lines that trigger logical channels. Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com> Reviewed-by: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com> Acked-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Vinod Koul <vinod.koul@intel.com> Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/ste_dma40.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index 760576b85641..9f8964a0a287 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -2180,11 +2180,24 @@ static void __d40_set_prio_rt(struct d40_chan *d40c, int dev_type, bool src)
{
bool realtime = d40c->dma_cfg.realtime;
bool highprio = d40c->dma_cfg.high_priority;
- u32 prioreg = highprio ? D40_DREG_PSEG1 : D40_DREG_PCEG1;
u32 rtreg = realtime ? D40_DREG_RSEG1 : D40_DREG_RCEG1;
u32 event = D40_TYPE_TO_EVENT(dev_type);
u32 group = D40_TYPE_TO_GROUP(dev_type);
u32 bit = 1 << event;
+ u32 prioreg;
+
+ /*
+ * Due to a hardware bug, in some cases a logical channel triggered by
+ * a high priority destination event line can generate extra packet
+ * transactions.
+ *
+ * The workaround is to not set the high priority level for the
+ * destination event lines that trigger logical channels.
+ */
+ if (!src && chan_is_logical(d40c))
+ highprio = false;
+
+ prioreg = highprio ? D40_DREG_PSEG1 : D40_DREG_PCEG1;
/* Destination event lines are stored in the upper halfword */
if (!src)