Patchwork fix the interrupt loss problem on powerpc IPIC (2.6.25-2.6.28)

login
register
mail settings
Submitter dayu@datangmobile.cn
Date Feb. 18, 2009, 2:16 a.m.
Message ID <D728AD1FA2543948B89DE29C5BF4CD0716AC37FD@bjmail1.bj.datangmobile.com>
Download mbox | patch
Permalink /patch/23321/
State Superseded, archived
Delegated to: Kumar Gala
Headers show

Comments

dayu@datangmobile.cn - Feb. 18, 2009, 2:16 a.m.
From: Da Yu <dayu@datangmobile.cn>
Date: Wed, 18 Feb 2009 19:58:20 +0800
Subject: [PATCH] fix the interrupt loss problem on powerpc IPIC (2.6.25-2.6.28)

Signed-off-by: Da Yu <dayu@datangmobile.cn>
---





-----邮件原件-----
发件人: Li Yang [mailto:leoli@freescale.com] 
发送时间: 2009年2月17日 22:38
收件人: Kumar Gala
抄送: 笪禹; linux-kernel@vger.kernel.org; linuxppc-dev@ozlabs.org
主题: Re: [PATCH] fix the interrupt loss problem on powerpc IPIC (2.6.23)

On Tue, Feb 17, 2009 at 10:12 PM, Kumar Gala <galak@kernel.crashing.org> wrote:
>
> On Feb 17, 2009, at 6:44 AM, <dayu@datangmobile.cn> 
> <dayu@datangmobile.cn>
> wrote:
>
>> From: Da Yu <dayu@datangmobile.cn>
>> Date: Tue, 17 Feb 2009 19:58:20 +0800
>> Subject: [PATCH] fix the interrupt loss problem on powerpc IPIC 
>> (2.6.23)
>>
>> Signed-off-by: Da Yu <dayu@datangmobile.cn>
>> ---
>
> Please provide a bit more description as to why this fixes the issue.

The pending register is write 1 clear.  If there are more than one external interrupts pending at the same time, acking the first interrupt will also clear other interrupt pending bits.  That will cause loss of interrupt.

- Leo
Olof Johansson - Feb. 18, 2009, 2:43 a.m.
On Wed, Feb 18, 2009 at 10:16:07AM +0800, dayu@datangmobile.cn wrote:
> From: Da Yu <dayu@datangmobile.cn>
> Date: Wed, 18 Feb 2009 19:58:20 +0800
> Subject: [PATCH] fix the interrupt loss problem on powerpc IPIC (2.6.25-2.6.28)
> 
> Signed-off-by: Da Yu <dayu@datangmobile.cn>

Still no proper explanation in the patch.

Also, with this change, is 'temp' really needed, or can you just pass in the
mask by hand?


-Olof

> ---
> 
> --- a/arch/powerpc/sysdev/ipic.c	2009-02-18 09:47:04.000000000 +0800
> +++ b/arch/powerpc/sysdev/ipic.c	2009-02-18 09:46:34.000000000 +0800
> @@ -568,8 +568,7 @@ static void ipic_ack_irq(unsigned int vi
> 
>  	spin_lock_irqsave(&ipic_lock, flags);
> 
> -	temp = ipic_read(ipic->regs, ipic_info[src].ack);
> -	temp |= (1 << (31 - ipic_info[src].bit));
> +	temp = 1 << (31 - ipic_info[src].bit);
>  	ipic_write(ipic->regs, ipic_info[src].ack, temp);
> 
>  	/* mb() can't guarantee that ack is finished.  But it does finish

Patch

--- a/arch/powerpc/sysdev/ipic.c	2009-02-18 09:47:04.000000000 +0800
+++ b/arch/powerpc/sysdev/ipic.c	2009-02-18 09:46:34.000000000 +0800
@@ -568,8 +568,7 @@  static void ipic_ack_irq(unsigned int vi

 	spin_lock_irqsave(&ipic_lock, flags);

-	temp = ipic_read(ipic->regs, ipic_info[src].ack);
-	temp |= (1 << (31 - ipic_info[src].bit));
+	temp = 1 << (31 - ipic_info[src].bit);
 	ipic_write(ipic->regs, ipic_info[src].ack, temp);

 	/* mb() can't guarantee that ack is finished.  But it does finish
@@ -592,8 +591,7 @@  static void ipic_mask_irq_and_ack(unsign
 	temp &= ~(1 << (31 - ipic_info[src].bit));
 	ipic_write(ipic->regs, ipic_info[src].mask, temp);

-	temp = ipic_read(ipic->regs, ipic_info[src].ack);
-	temp |= (1 << (31 - ipic_info[src].bit));
+	temp = 1 << (31 - ipic_info[src].bit);
 	ipic_write(ipic->regs, ipic_info[src].ack, temp);

 	/* mb() can't guarantee that ack is finished.  But it does finish