lwn.git/drivers/dma/mxs-dma.c, branch next

dma: mxs-dma: Use semaphores for cyclic DMA

2013-11-13T10:08:31+00:00

mxs dma channel hardware reset command is not reliable and can cause a channel stall. The only way to fix the channel stall is a DMA engine reset. To avoid channel resets we use the hardware semaphore counter. For each transmitted segment, the DMA channel will decrease the counter by one. To use this mechanism with cyclic DMA, we need to increase the semaphore counter with each completed DMA command in the interrupt handler. To avoid any interruptions between the DMA transfers, the semaphore counter is initialized with 2. This way the counter can be increased in the interrupt handler without an influence on the transfer of the DMA engine. When disabling the channel, we stop increasing the semaphore counter in the interrupt handler. This patch was tested on i.MX28 with the SAIF DMA channel. Signed-off-by: Markus Pargmann Signed-off-by: Vinod Koul

dma: mxs-dma: Update state after channel reset

2013-11-13T10:08:30+00:00

After a channel reset, the channel stops running automatically. The state update was missing so that a channel perperation right after a channel reset failed. Signed-off-by: Markus Pargmann Signed-off-by: Vinod Koul

dma: mxs-dma: Fix channel reset hardware bug

2013-11-13T10:08:30+00:00

This is no official errata, but I noticed that the channel reset may stop working if the DMA state engine is in the READ_FLUSH state. This patch uses the channel debug1 register to wait for the DMA statemachine to leave the READ_FLUSH state. After that we can continue to reset the channel. Tested on i.MX28. Signed-off-by: Markus Pargmann Signed-off-by: Vinod Koul

dma: mxs-dma: Report correct residue for cyclic DMA

2013-11-13T10:08:30+00:00

Use the channel's buffer address register to calculate correct residue value for tx_status. Signed-off-by: Markus Pargmann Signed-off-by: Vinod Koul

dma: mxs-dma: Cleanup interrupt handler

2013-11-13T10:08:30+00:00

The DMA interrupt handler uses its controll registers to handle all available channel interrupts it can find. This patch changes it to handle only one interrupt by directly mapping irq number to channel. It also includes a cleanup of the ctrl-register usage. Signed-off-by: Markus Pargmann Signed-off-by: Vinod Koul

dmaengine: mxs-dma: use DMA_COMPLETE for dma completion status

2013-10-25T05:46:10+00:00

Acked-by: Dan Williams Acked-by: Linus Walleij Signed-off-by: Vinod Koul

dma: mxs-dma: remove code left from generic DMA binding conversion

2013-08-19T08:50:21+00:00

With all mxs-dma clients moved to use generic DMA helper, the code left from generic DMA binding conversion can be removed now. Signed-off-by: Shawn Guo Reviewed-by: Arnd Bergmann Signed-off-by: Vinod Koul

mxs-dma: remove useless variable

2013-08-05T04:02:24+00:00

last_used variable is applied only once, so, let's substitute it by its value. Signed-off-by: Andy Shevchenko Signed-off-by: Vinod Koul

dma: mxs-dma: Staticize mxs_dma_xlate

2013-07-05T06:10:33+00:00

Fix the following sparse warning: drivers/dma/mxs-dma.c:696:17: warning: symbol 'mxs_dma_xlate' was not declared. Should it be static? Signed-off-by: Fabio Estevam Acked-by: Shawn Guo Signed-off-by: Vinod Koul

dma: mxs-dma: move to generic device tree binding

2013-04-04T13:22:43+00:00

Update mxs-dma driver to adopt generic DMA device tree binding. It calls of_dma_controller_register() with mxs specific of_dma_xlate to get the generic DMA device tree helper support. Then DMA clients only need to call dma_request_slave_channel() for requesting a DMA channel from dmaengine. The existing way of requesting channel, clients directly call dma_request_channel(), still work there, and will be removed after all mxs-dma clients get converted to generic DMA device tree helper. Signed-off-by: Shawn Guo Reviewed-by: Arnd Bergmann