From: Brian Niebuhr Date: Tue, 9 Mar 2010 22:48:03 +0000 (-0600) Subject: davinci: edma: clear events in edma_start() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=bb17ef102b72e38557bfa829511e06c4bd3bb972;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git davinci: edma: clear events in edma_start() This patch fixes an issue where a DMA channel can erroneously process an event generated by a previous transfer. A failure case is where DMA is being used for SPI transmit and receive channels on OMAP L138. In this case there is a single bit that controls all event generation from the SPI peripheral. Therefore it is possible that between when edma_stop() has been called for the transmit channel on a previous transfer and edma_start() is called for the transmit channel on a subsequent transfer, that a transmit event has been generated. The fix is to clear events in edma_start(). This prevents false events from being processed when events are enabled for that channel. Signed-off-by: Brian Niebuhr Signed-off-by: Kevin Hilman --- diff --git a/arch/arm/mach-davinci/dma.c b/arch/arm/mach-davinci/dma.c index 15dd886df04c..260485cc76df 100644 --- a/arch/arm/mach-davinci/dma.c +++ b/arch/arm/mach-davinci/dma.c @@ -1266,7 +1266,8 @@ int edma_start(unsigned channel) /* EDMA channel with event association */ pr_debug("EDMA: ER%d %08x\n", j, edma_shadow0_read_array(ctlr, SH_ER, j)); - /* Clear any pending error */ + /* Clear any pending event or error */ + edma_write_array(ctlr, EDMA_ECR, j, mask); edma_write_array(ctlr, EDMA_EMCR, j, mask); /* Clear any SER */ edma_shadow0_write_array(ctlr, SH_SECR, j, mask);