[PATCH v2 04/15] ARM: mxs: Add interrupt support

[Uwe Kleine-König]

Hello Shawn,

On Wed, Dec 08, 2010 at 04:27:56PM +0800, Shawn Guo wrote:
> 2010/12/8 Uwe Kleine-König <u.kleine-koenig at pengutronix.de>:
> > On Wed, Dec 08, 2010 at 12:31:54AM +0800, Shawn Guo wrote:
> [...]
> >> +
> >> +static void icoll_ack_irq(unsigned int irq)
> >> +{
> >> +     __raw_writel(0, icoll_base + HW_ICOLL_VECTOR);
> > You need to write this before handling the irq, no?  Note this question
> > is a repetition.  You answered "No need, indeed.  Will remove it."
> > According to MCIMX28RM a write to HW_ICOLL_VECTOR "indicates the
> > in-service state".  Are you sure this is not needed?  If no (i.e. it's
> > needed) the write should go into entry-macro.S.  As I don't have
> > hardware yet I cannot test that.  Maybe it's only needed when the
> > priority levels are used?!
> >
> Sorry. I made a mistake.  I thought I had tested the removal of line
> and gave the comment, but actually not. The line is needed, and image
> will stop working without the line.
> 
> Regarding to moving the writing to register VECTOR into entry-macro.S,
> can you please help me understand the reason behind the suggestion?
Section 5.2.1 of MCIMX28RM writes:

	After the CPU enters the interrupt service routine, it must
	notify the interrupt collector as soon as possible. Software
	indicates the in-service state by writing to the HW_ICOLL_VECTOR
	register.

Best regards
Uwe

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