2012-06-20 20:36:56

by Stephan Linz

Subject: [PATCH] microblaze: improve failure handling for GPIO reset

Early exit from of_platform_reset_gpio_probe() if there
was no GPIO reset line configured.

Avoid kernel oops in gpio_system_reset():

[ 27.413294] Restarting system.
[ 27.415674] Machine restart...
[ 27.418787] Oops: kernel access of bad area, sig: 11
[ 27.423252] Registers dump: mode=83871D1C
[ 27.427428] r1=00000000, r2=00000000, r3=FFFFFEF8, r4=00000000
[ 27.433310] r5=C026AED0, r6=00000001, r7=00000068, r8=00000000
[ 27.439189] r9=C3871DAC, r10=000011A5, r11=00000000, r12=0000000A
[ 27.445318] r13=00000000, r14=0000000F, r15=C00029BC, r16=00000000
[ 27.451558] r17=C011DE8C, r18=80000115, r19=0000000F, r20=48184ED8
[ 27.457770] r21=00000000, r22=FFFFFFEA, r23=00000001, r24=FEE1DEAD
[ 27.463982] r25=00000054, r26=1000B1C8, r27=00000000, r28=00000000
[ 27.470208] r29=00000000, r30=00000000, r31=C32D30C0, rPC=C011DE8C
[ 27.476433] msr=000042A2, ear=0000004B, esr=00000872, fsr=342E3732

Signed-off-by: Stephan Linz <[email protected]>
---
arch/microblaze/kernel/reset.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/microblaze/kernel/reset.c b/arch/microblaze/kernel/reset.c
index 88a0163..7a08071 100644
--- a/arch/microblaze/kernel/reset.c
+++ b/arch/microblaze/kernel/reset.c
@@ -28,6 +28,7 @@ void of_platform_reset_gpio_probe(void)
if (!gpio_is_valid(handle)) {
printk(KERN_INFO "Skipping unavailable RESET gpio %d (%s)\n",
handle, "reset");
+ return;
}

ret = gpio_request(handle, "reset");
@@ -60,7 +61,8 @@ err:

static void gpio_system_reset(void)
{
- gpio_set_value(handle, 1 - reset_val);
+ if (gpio_is_valid(handle))
+ gpio_set_value(handle, 1 - reset_val);
}
#else
#define gpio_system_reset() do {} while (0)
@@ -74,6 +76,7 @@ void machine_restart(char *cmd)
{
printk(KERN_NOTICE "Machine restart...\n");
gpio_system_reset();
+ printk(KERN_NOTICE "Dump stack on machines without reset line ...\n");
dump_stack();
while (1)
;
--
1.7.0.4

2012-06-21 06:34:49

by Michal Simek

Subject: Re: [PATCH] microblaze: improve failure handling for GPIO reset

On 06/20/2012 10:36 PM, Stephan Linz wrote:
> Early exit from of_platform_reset_gpio_probe() if there
> was no GPIO reset line configured.
>
> Avoid kernel oops in gpio_system_reset():
>
> [ 27.413294] Restarting system.
> [ 27.415674] Machine restart...
> [ 27.418787] Oops: kernel access of bad area, sig: 11
> [ 27.423252] Registers dump: mode=83871D1C
> [ 27.427428] r1=00000000, r2=00000000, r3=FFFFFEF8, r4=00000000
> [ 27.433310] r5=C026AED0, r6=00000001, r7=00000068, r8=00000000
> [ 27.439189] r9=C3871DAC, r10=000011A5, r11=00000000, r12=0000000A
> [ 27.445318] r13=00000000, r14=0000000F, r15=C00029BC, r16=00000000
> [ 27.451558] r17=C011DE8C, r18=80000115, r19=0000000F, r20=48184ED8
> [ 27.457770] r21=00000000, r22=FFFFFFEA, r23=00000001, r24=FEE1DEAD
> [ 27.463982] r25=00000054, r26=1000B1C8, r27=00000000, r28=00000000
> [ 27.470208] r29=00000000, r30=00000000, r31=C32D30C0, rPC=C011DE8C
> [ 27.476433] msr=000042A2, ear=0000004B, esr=00000872, fsr=342E3732
>
> Signed-off-by: Stephan Linz<[email protected]>
> ---
> arch/microblaze/kernel/reset.c | 5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/arch/microblaze/kernel/reset.c b/arch/microblaze/kernel/reset.c
> index 88a0163..7a08071 100644
> --- a/arch/microblaze/kernel/reset.c
> +++ b/arch/microblaze/kernel/reset.c
> @@ -28,6 +28,7 @@ void of_platform_reset_gpio_probe(void)
> if (!gpio_is_valid(handle)) {
> printk(KERN_INFO "Skipping unavailable RESET gpio %d (%s)\n",
> handle, "reset");
> + return;
> }
>
> ret = gpio_request(handle, "reset");
> @@ -60,7 +61,8 @@ err:
>
> static void gpio_system_reset(void)
> {
> - gpio_set_value(handle, 1 - reset_val);
> + if (gpio_is_valid(handle))
> + gpio_set_value(handle, 1 - reset_val);
> }
> #else
> #define gpio_system_reset() do {} while (0)
> @@ -74,6 +76,7 @@ void machine_restart(char *cmd)
> {
> printk(KERN_NOTICE "Machine restart...\n");
> gpio_system_reset();
> + printk(KERN_NOTICE "Dump stack on machines without reset line ...\n");
> dump_stack();
> while (1)
> ;

Your changes looks good. Some weeks ago we have changed this code a little bit too by removing dump_stack()
and change printk message to "NO reset GPIO available in the system" or similar.
I think we can add these two changes together because truth is that dump_stack didn't give you any useful
output.

Thanks,
Michal



--
Michal Simek, Ing. (M.Eng)
w: http://www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian

2012-06-21 16:34:28

by Stephan Linz

Subject: Re: [PATCH] microblaze: improve failure handling for GPIO reset

Am Donnerstag, den 21.06.2012, 08:34 +0200 schrieb Michal Simek:
> On 06/20/2012 10:36 PM, Stephan Linz wrote:
> > Early exit from of_platform_reset_gpio_probe() if there
> > was no GPIO reset line configured.
> >
> > Avoid kernel oops in gpio_system_reset():
> >
> > [ 27.413294] Restarting system.
> > [ 27.415674] Machine restart...
> > [ 27.418787] Oops: kernel access of bad area, sig: 11
> > [ 27.423252] Registers dump: mode=83871D1C
> > [ 27.427428] r1=00000000, r2=00000000, r3=FFFFFEF8, r4=00000000
> > [ 27.433310] r5=C026AED0, r6=00000001, r7=00000068, r8=00000000
> > [ 27.439189] r9=C3871DAC, r10=000011A5, r11=00000000, r12=0000000A
> > [ 27.445318] r13=00000000, r14=0000000F, r15=C00029BC, r16=00000000
> > [ 27.451558] r17=C011DE8C, r18=80000115, r19=0000000F, r20=48184ED8
> > [ 27.457770] r21=00000000, r22=FFFFFFEA, r23=00000001, r24=FEE1DEAD
> > [ 27.463982] r25=00000054, r26=1000B1C8, r27=00000000, r28=00000000
> > [ 27.470208] r29=00000000, r30=00000000, r31=C32D30C0, rPC=C011DE8C
> > [ 27.476433] msr=000042A2, ear=0000004B, esr=00000872, fsr=342E3732
> >
> > Signed-off-by: Stephan Linz<[email protected]>
> > ---
> > arch/microblaze/kernel/reset.c | 5 ++++-
> > 1 files changed, 4 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/microblaze/kernel/reset.c b/arch/microblaze/kernel/reset.c
> > index 88a0163..7a08071 100644
> > --- a/arch/microblaze/kernel/reset.c
> > +++ b/arch/microblaze/kernel/reset.c
> > @@ -28,6 +28,7 @@ void of_platform_reset_gpio_probe(void)
> > if (!gpio_is_valid(handle)) {
> > printk(KERN_INFO "Skipping unavailable RESET gpio %d (%s)\n",
> > handle, "reset");
> > + return;
> > }
> >
> > ret = gpio_request(handle, "reset");
> > @@ -60,7 +61,8 @@ err:
> >
> > static void gpio_system_reset(void)
> > {
> > - gpio_set_value(handle, 1 - reset_val);
> > + if (gpio_is_valid(handle))
> > + gpio_set_value(handle, 1 - reset_val);
> > }
> > #else
> > #define gpio_system_reset() do {} while (0)
> > @@ -74,6 +76,7 @@ void machine_restart(char *cmd)
> > {
> > printk(KERN_NOTICE "Machine restart...\n");
> > gpio_system_reset();
> > + printk(KERN_NOTICE "Dump stack on machines without reset line ...\n");
> > dump_stack();
> > while (1)
> > ;
>
> Your changes looks good. Some weeks ago we have changed this code a little bit too by removing dump_stack()
> and change printk message to "NO reset GPIO available in the system" or similar.
> I think we can add these two changes together because truth is that dump_stack didn't give you any useful
> output.

OK, more important are the changes in of_platform_reset_gpio_probe() and
gpio_system_reset() ... the printk message should be a hint. Merge
together with your work as you like / need ...


br,
Stephan