Hi,
> On 03/14/2012 07:49 AM, Gupta, Ajay Kumar wrote:
> >> I *think* that the DMA engine is performing some access on its own to
> >> those registers behind the bridge which leads to the same read&
> clear
> >> interrupt race.
> >
> > DMA driver (CPPI4.1) is not yet available for AM35x but DMA might read
> > Mentor core registers. The solution is to disable non-PDR interrupt in
> > CONTROL register (bit D3) at offset 0x0004.
> > "D3 | uint | USB non-PDR interrupt enable"
>
> I see. Care to send a patch to replace my "force DMA off"?
We need to enable non-PDR (Mentor core only) interrupts using below patch.
------------------------------------------------------------------------
diff --git a/drivers/usb/musb/am35x.c b/drivers/usb/musb/am35x.c
index e233d2b..cbd17e5 100644
--- a/drivers/usb/musb/am35x.c
+++ b/drivers/usb/musb/am35x.c
@@ -68,6 +68,7 @@
/* Control register bits */
#define AM35X_SOFT_RESET_MASK 1
+#define AM35X_ENABLE_NON_PDR (1 << 3)
/* USB interrupt register bits */
#define AM35X_INTR_USB_SHIFT 16
@@ -353,7 +354,7 @@ static int am35x_musb_init(struct musb *musb)
struct musb_hdrc_platform_data *plat = dev->platform_data;
struct omap_musb_board_data *data = plat->board_data;
void __iomem *reg_base = musb->ctrl_base;
- u32 rev;
+ u32 rev, ctrl;
musb->mregs += USB_MENTOR_CORE_OFFSET;
@@ -383,6 +384,11 @@ static int am35x_musb_init(struct musb *musb)
msleep(5);
+ /* Enable the non-PDR interrupts */
+ ctrl = musb_readl(reg_base, USB_CTRL_REG);
+ ctrl |= AM35X_ENABLE_NON_PDR;
+ musb_writel(reg_base, USB_CTRL_REG, ctrl);
+
musb->isr = am35x_musb_interrupt;
/* clear level interrupt */
------------------------------------------------------------------------
Ajay
>
> > Ajay
>
> Sebastian
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