On 28-11-18, 13:15, Peter Ujfalusi wrote:
On 12/11/2018 17.40, Bin Liu wrote:
Can you fix up the subject line to: dmaengine: ti: cppi4: delete channel from pending list when stop channel
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.
So, let me see if I understand this correctly:
- client issued a transfer _after_ the cppi4 driver is suspended
- cppi41_dma_issue_pending() will place it to pending list and will not
start the transfer right away as cdd->is_suspended is true.
- on resume the cppi4 will pick up the pending transfers from the
pending list
This is so far a sane thing to do.
If I guess right, then after the issue_pending the client driver will call terminate_all, presumably from it's suspend callback?
As per the purpose of terminate_all we should terminated all future transfers on the channel, so clearing the pending list is the correct thing to do.
With the fixed subject: Reviewed-by: Peter Ujfalusi peter.ujfalusi@ti.com
Thanks Peter,
Applied after fixing the title, thanks