Hi,
This series fix resource freeing synchronization by:
1. Patch 1/3
Store the IRQ number in the global struct so it can be used later
together with synchronize_irq().
2. Patch 2/3
Adding support for the device_synchronize() callback in patch 2/3.
3. Patch 3/3
Waiting for any ISR that might still be running after the channel is
halted prior to freeing its resources. This was patch previously part
of a patch sent out by Yoshihiro Shimoda and authored by Hiroyuki
Yokoyama, see [1].
In that thread it was suggested by Lars-Peter Clausen to instead
implement the device_synchronize() callback. Unfortunately this is not
enough to solve the issue. In rcar_dmac_free_chan_resources() the
channel is halted by a call to rcar_dmac_chan_halt() and then directly
moves on to freeing resources, here it is still needed to add a wait
for any ISR to finish before freeing the resources, despite that a
device_synchronize() have been added. This is because call chain:
dma_release_channel()
dma_chan_put()
dmaengine_synchronize()
rcar_dmac_free_chan_resources()
rcar_dmac_chan_halt()
Here dmaengine_synchronize() is called prior to rcar_dmac_chan_halt()
so an extra synchronisation to wait for any running ISR is still
needed.
By both adding a device_synchronize() which can be used in conjunction
with device_terminate_all() and fiends and by adding an explicit
synchronize_irq() when freeing channel resources I feel the
synchronisation for freeing channel resources are in a much better
shape. It also solves the issue in the original mail thread.
The series is based on v4.12-rc1 and is tested on r8a7795 Salvator-X.
1. https://patchwork.kernel.org/patch/9557691/
* Changes since v1
- Rebased to v4.12-rc1
Niklas Söderlund (3):
dmaengine: rcar-dmac: store channel IRQ in struct rcar_dmac_chan
dmaengine: rcar-dmac: implement device_synchronize()
dmaengine: rcar-dmac: wait for ISR to finish before freeing resources
drivers/dma/sh/rcar-dmac.c | 27 +++++++++++++++++++++------
1 file changed, 21 insertions(+), 6 deletions(-)
--
2.13.0
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