[PATCH 4.4 81/91] dmaengine: cppi41: delete channel from pending list when stop channel

Greg Kroah-Hartman
2018-12-11T15:48:08Z

From: Bin Liu <b-liu@ti.com>

commit 59861547ec9a9736e7882f6fb0c096a720ff811a upstream.

The driver defines three states for a cppi channel.
- idle: .chan_busy == 0 && not in .pending list
- pending: .chan_busy == 0 && in .pending list
- busy: .chan_busy == 1 && not in .pending list

There are cases in which the cppi channel could be in the pending state
when cppi41_dma_issue_pending() is called after cppi41_runtime_suspend()
is called.

cppi41_stop_chan() has a bug for these cases to set channels to idle state.
It only checks the .chan_busy flag, but not the .pending list, then later
when cppi41_runtime_resume() is called the channels in .pending list will
be transitioned to busy state.

Removing channels from the .pending list solves the problem.

Fixes: 975faaeb9985 ("dma: cppi41: start tear down only if channel is busy")
Cc: stable@vger.kernel.org # v3.15+
Signed-off-by: Bin Liu <b-liu@ti.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/dma/cppi41.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/dma/cppi41.c
+++ b/drivers/dma/cppi41.c
@@ -628,8 +628,22 @@ static int cppi41_stop_chan(struct dma_c

desc_phys = lower_32_bits(c->desc_phys);
desc_num = (desc_phys - cdd->descs_phys) / sizeof(struct cppi41_desc);
- if (!cdd->chan_busy[desc_num])
+ if (!cdd->chan_busy[desc_num]) {
+ struct cppi41_channel *cc, *_ct;
+
+ /*
+ * channels might still be in the pendling list if
+ * cppi41_dma_issue_pending() is called after
+ * cppi41_runtime_suspend() is called
+ */
+ list_for_each_entry_safe(cc, _ct, &cdd->pending, node) {
+ if (cc != c)
+ continue;
+ list_del(&cc->node);
+ break;
+ }
return 0;
+ }

ret = cppi41_tear_down_chan(c);
if (ret)