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| /openbmc/linux/drivers/spi/ |
| H A D | spi-bcm2835.c | 2527704d Thu Nov 29 09:45:24 CST 2018 Lukas Wunner <lukas@wunner.de> spi: bcm2835: Synchronize with callback on DMA termination
Commit b36f09c3c441 ("dmaengine: Add transfer termination
synchronization support") deprecated dmaengine_terminate_all() in favor
of dmaengine_terminate_sync() and dmaengine_terminate_async() to avoid
freeing resources used by the DMA callback before its execution has
concluded.
Commit de92436ac40f ("dmaengine: bcm2835-dma: Use vchan_terminate_vdesc()
instead of desc_free") amended the BCM2835 DMA driver with an
implementation of ->device_synchronize(), which is a prerequisite for
dmaengine_terminate_sync(). Thus, clients of the DMA driver (such as
the BCM2835 SPI driver) may now be converted to the new API.
It is generally desirable to use the _sync() variant except in atomic
context. There is only a single occurrence where the BCM2835 SPI driver
calls dmaengine_terminate_all() in atomic context and that is in
bcm2835_spi_dma_done() (the RX DMA channel's callback) to terminate the
TX DMA channel. The TX DMA channel doesn't have a callback (yet), hence
it is safe to use the _async() variant there.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Frank Pavlic <f.pavlic@kunbus.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2527704d Thu Nov 29 09:45:24 CST 2018 Lukas Wunner <lukas@wunner.de> spi: bcm2835: Synchronize with callback on DMA termination
Commit b36f09c3c441 ("dmaengine: Add transfer termination
synchronization support") deprecated dmaengine_terminate_all() in favor
of dmaengine_terminate_sync() and dmaengine_terminate_async() to avoid
freeing resources used by the DMA callback before its execution has
concluded.
Commit de92436ac40f ("dmaengine: bcm2835-dma: Use vchan_terminate_vdesc()
instead of desc_free") amended the BCM2835 DMA driver with an
implementation of ->device_synchronize(), which is a prerequisite for
dmaengine_terminate_sync(). Thus, clients of the DMA driver (such as
the BCM2835 SPI driver) may now be converted to the new API.
It is generally desirable to use the _sync() variant except in atomic
context. There is only a single occurrence where the BCM2835 SPI driver
calls dmaengine_terminate_all() in atomic context and that is in
bcm2835_spi_dma_done() (the RX DMA channel's callback) to terminate the
TX DMA channel. The TX DMA channel doesn't have a callback (yet), hence
it is safe to use the _async() variant there.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Frank Pavlic <f.pavlic@kunbus.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
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