Re: [PATCH] fix the interrupt loss problem on powerpc IPIC(2.6.25-2.6.28)

renew description in  the patch,  with this change the 'temp'  is still =
used to make code clear.

___________________________________________

From: Da Yu <redacted>
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)

Description: The interrupt pending register is write 1 clear.  If there =
are more than one external interrupts pending at the same time, acking =
the first interrupt by reading pending register then OR the =
corresponding bit and write back to pending register will also clear =
other interrupt pending bits.  That will cause loss of interrupt.

Signed-off-by: Da Yu <redacted>
---

--- 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 =3D ipic_read(ipic->regs, ipic_info[src].ack);
-	temp |=3D (1 << (31 - ipic_info[src].bit));
+	temp =3D 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 &=3D ~(1 << (31 - ipic_info[src].bit));
 	ipic_write(ipic->regs, ipic_info[src].mask, temp);

-	temp =3D ipic_read(ipic->regs, ipic_info[src].ack);
-	temp |=3D (1 << (31 - ipic_info[src].bit));
+	temp =3D 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

=20
=20

-----=D3=CA=BC=FE=D4=AD=BC=FE-----
=B7=A2=BC=FE=C8=CB: Olof Johansson [mailto:olof@lixom.net]=20
=B7=A2=CB=CD=CA=B1=BC=E4: 2009=C4=EA2=D4=C218=C8=D5 10:43
=CA=D5=BC=FE=C8=CB: =F3=CE=D3=ED
=B3=AD=CB=CD: leoli@freescale.com; galak@kernel.crashing.org; =
linuxppc-dev@ozlabs.org; linux-kernel@vger.kernel.org
=D6=F7=CC=E2: Re: [PATCH] fix the interrupt loss problem on powerpc =
IPIC(2.6.25-2.6.28)

On Wed, Feb 18, 2009 at 10:16:07AM +0800, dayu@datangmobile.cn wrote:

From: Da Yu <redacted>
Date: Wed, 18 Feb 2009 19:58:20 +0800
Subject: [PATCH] fix the interrupt loss problem on powerpc IPIC=20
(2.6.25-2.6.28)
=20
Signed-off-by: Da Yu <redacted>

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

On Feb 17, 2009, at 11:47 PM, [off-list ref] <dayu@datangmobile.cn 
 > wrote:

From: Da Yu <redacted>
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)

Description: The interrupt pending register is write 1 clear.  If  
there are more than one external interrupts pending at the same  
time, acking the first interrupt by reading pending register then OR  
the corresponding bit and write back to pending register will also  
clear other interrupt pending bits.  That will cause loss of  
interrupt.

Signed-off-by: Da Yu <redacted>
---

applied to next

- k