From: Peter Ujfalusi Subject: Re: [PATCH 1/3] ARM: common: edma: clear completion interrupts on stop Date: Mon, 27 Apr 2015 14:55:26 +0300 Message-ID: <553E23AE.5010601@ti.com> References: <87wq0xaivk.fsf@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <87wq0xaivk.fsf@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org To: John Ogness , linux-kernel@vger.kernel.org Cc: linux-serial@vger.kernel.org, Sekhar Nori , Greg Kroah-Hartman , Sebastian Andrzej Siewior List-Id: linux-serial@vger.kernel.org On 04/27/2015 02:52 PM, John Ogness wrote: > When stopping a DMA transfer with interrupts disabled it is possible > that the DMA transfer completes before the events are cleared. In > this case the completion interrupt will be pending, causing a > completion callback after the transfer was stopped. >=20 > By clearing the completion interrupt for the stopping channel it is > ensured that no completion event will be generated after the stop. Acked-by: Peter Ujfalusi > Signed-off-by: John Ogness > --- > arch/arm/common/edma.c | 3 +++ > 1 file changed, 3 insertions(+) >=20 > diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c > index 5662a87..873dbfc 100644 > --- a/arch/arm/common/edma.c > +++ b/arch/arm/common/edma.c > @@ -1350,6 +1350,9 @@ void edma_stop(unsigned channel) > edma_shadow0_write_array(ctlr, SH_SECR, j, mask); > edma_write_array(ctlr, EDMA_EMCR, j, mask); > =20 > + /* clear possibly pending completion interrupt */ > + edma_shadow0_write_array(ctlr, SH_ICR, j, mask); > + > pr_debug("EDMA: EER%d %08x\n", j, > edma_shadow0_read_array(ctlr, SH_EER, j)); > =20 >=20 --=20 P=E9ter