From mboxrd@z Thu Jan 1 00:00:00 1970 From: mika.westerberg@iki.fi (Mika Westerberg) Date: Wed, 21 Mar 2012 21:32:31 +0200 Subject: [PATCH] ep93xx: Implement double buffering for M2M DMA channels In-Reply-To: References: <4F683B36.8090101@metasoft.pl> Message-ID: <20120321193231.GA3740@mwesterb-mobl.ger.corp.intel.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Mar 21, 2012 at 12:12:11PM -0500, H Hartley Sweeten wrote: > On Tuesday, March 20, 2012 1:09 AM, Rafal Prylowski wrote: > > > > Implement double buffering for M2M DMA channels. > > > > Signed-off-by: Rafal Prylowski > > Hmm... This isn't working on my ep9307 board... > > When the system boots I get stormed with messages: > > dma dma1chan0: unknown interrupt! > dma dma1chan0: unknown interrupt! > dma dma1chan0: unknown interrupt! > dma dma1chan1: unknown interrupt! > dma dma1chan1: unknown interrupt! > dma dma1chan1: unknown interrupt! > dma dma1chan0: unknown interrupt! > dma dma1chan0: unknown interrupt! > dma dma1chan1: unknown interrupt! > > Note, I have use_dma set for the ep93xx_spi driver and am using mmc_spi. > > Also note, without your patch I also get a couple messages: > > dma dma1chan1: got interrupt while active list is empty > > But, the mmc card is working fine. I haven't tracked down why I get these > yet. Mika, any ideas? I've noticed the same. But they also happen without this patch applied. I've tracked it down to MULTI_IRQ_HANDLER support patches for ARM vic but not sure what might be wrong there (or is the ep93xx_dma driver behaving badly). I noticed that when we get that 'got interrupt while active list is empty' we don't have any interrupts set in the M2M_INTERRUPT register but we still got an interrupt.. weird. Below is a workaround I've been using lately but it certainly is a hack and we should figure out what is the root cause for this. diff --git a/arch/arm/common/vic.c b/arch/arm/common/vic.c index dcb004a..cb6b49a 100644 --- a/arch/arm/common/vic.c +++ b/arch/arm/common/vic.c @@ -441,11 +441,9 @@ static int handle_one_vic(struct vic_device *vic, struct pt_regs *regs) u32 stat, irq; int handled = 0; - stat = readl_relaxed(vic->base + VIC_IRQ_STATUS); - while (stat) { + while ((stat = readl_relaxed(vic->base + VIC_IRQ_STATUS))) { irq = ffs(stat) - 1; handle_IRQ(irq_domain_to_irq(&vic->domain, irq), regs); - stat &= ~(1 << irq); handled = 1; }