From mboxrd@z Thu Jan 1 00:00:00 1970 From: stanley.miao@windriver.com (stanley.miao) Date: Mon, 24 May 2010 19:59:30 +0800 Subject: [PATCH 3/6] davinci: edma: clear events in edma_start() In-Reply-To: <1268841163-5868-4-git-send-email-khilman@deeprootsystems.com> References: <1268841163-5868-1-git-send-email-khilman@deeprootsystems.com> <1268841163-5868-4-git-send-email-khilman@deeprootsystems.com> Message-ID: <4BFA6A22.1000006@windriver.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org This patch causes that the sound can not work normally on OMAP_L138. Stanley. Kevin Hilman wrote: > From: Brian Niebuhr > > 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 > --- > arch/arm/mach-davinci/dma.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/arch/arm/mach-davinci/dma.c b/arch/arm/mach-davinci/dma.c > index 15dd886..260485c 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); >