From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sekhar Nori Subject: Re: [PATCH 7/9] ARM: edma: Don't clear EMR of channel in edma_stop Date: Tue, 30 Jul 2013 13:59:54 +0530 Message-ID: <51F77982.7030601@ti.com> References: <1375104595-16018-1-git-send-email-joelf@ti.com> <1375104595-16018-8-git-send-email-joelf@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1375104595-16018-8-git-send-email-joelf-l0cyMroinI0@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: Errors-To: davinci-linux-open-source-bounces-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org To: Joel Fernandes Cc: Mark Brown , Tony Lindgren , Grant Likely , Sricharan R , Russell King , Vinod Koul , Lokesh Vutla , Chris Ball , Arnd Bergmann , Rajendra Nayak , Rob Herring , Jason Kridner , Linux OMAP List , Linux ARM Kernel List , Linux DaVinci Kernel List , Balaji TK , Linux MMC List , Linux Kernel Mailing List , Santosh Shilimkar List-Id: linux-omap@vger.kernel.org On Monday 29 July 2013 06:59 PM, Joel Fernandes wrote: > We certainly don't want error conditions to be cleared anywhere 'anywhere' is a really loaded term. > as this will make us 'forget' about missed events. We depend on > knowing which events were missed in order to be able to reissue them. > This fixes a race condition where the EMR was being cleared > by the transfer completion interrupt handler. > > Basically, what was happening was: > > Missed event > | > | > V > SG1-SG2-SG3-Null > \ > \__TC Interrupt (Almost same time as ARM is executing > TC interrupt handler, an event got missed and also forgotten > by clearing the EMR). Sorry, but I dont see how edma_stop() is coming into picture in the race you describe? > The EMR is ultimately being cleared by the Error interrupt > handler once it is handled so we don't have to do it in edma_stop. This, I agree with. edma_clean_channel() also there to re-initialize the channel so doing it in edma_stop() certainly seems superfluous. Thanks, Sekhar > > Signed-off-by: Joel Fernandes > --- > arch/arm/common/edma.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c > index 10995b2..dec772e 100644 > --- a/arch/arm/common/edma.c > +++ b/arch/arm/common/edma.c > @@ -1328,7 +1328,6 @@ void edma_stop(unsigned channel) > edma_shadow0_write_array(ctlr, SH_EECR, j, mask); > edma_shadow0_write_array(ctlr, SH_ECR, j, mask); > edma_shadow0_write_array(ctlr, SH_SECR, j, mask); > - edma_write_array(ctlr, EDMA_EMCR, j, mask); > > pr_debug("EDMA: EER%d %08x\n", j, > edma_shadow0_read_array(ctlr, SH_EER, j)); >