lkml.org 
[lkml]   [2012]   [Mar]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] ep93xx: Implement double buffering for M2M DMA channels
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 <prylowski@metasoft.pl>
>
> 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;
}


\
 
 \ /
  Last update: 2012-03-21 20:35    [from the cache]
©2003-2011 Jasper Spaans