[PATCH] ARM: at91: panic when the mck rate is zero

[PATCH] ARM: at91: panic when the mck rate is zero

[Alexandre Belloni]

If the mck rate is zero, we'll hit the following warning:

WARNING: CPU: 0 PID: 0 at arch/arm/mach-at91/at91sam926x_time.c:257 at91sam926x_pit_init+0x13c/0x260()

But the kernel will continue to try booting and face a lot of divisions by zero
when trying to handle the various clocks.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
 arch/arm/mach-at91/at91sam926x_time.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/mach-at91/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c
index 0f04ffe9c5a8..f060f6371392 100644
--- a/arch/arm/mach-at91/at91sam926x_time.c
+++ b/arch/arm/mach-at91/at91sam926x_time.c
@@ -250,6 +250,8 @@ void __init at91sam926x_pit_init(void)
 	if (IS_ERR(mck))
 		panic("AT91: PIT: Unable to get mck clk\n");
 	pit_rate = clk_get_rate(mck) / 16;
+	if (pit_rate == 0)
+		panic("AT91: PIT: can't continue, mck rate is zero\n");
 	pit_cycle = (pit_rate + HZ/2) / HZ;
 	WARN_ON(((pit_cycle - 1) & ~AT91_PIT_PIV) != 0);
 
-- 
1.8.3.2

[PATCH] ARM: at91: panic when the mck rate is zero

[Boris BREZILLON]

Le 20/03/2014 17:14, Alexandre Belloni a ?crit :
> If the mck rate is zero, we'll hit the following warning:
>
> WARNING: CPU: 0 PID: 0 at arch/arm/mach-at91/at91sam926x_time.c:257 at91sam926x_pit_init+0x13c/0x260()
>
> But the kernel will continue to try booting and face a lot of divisions by zero
> when trying to handle the various clocks.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
>   arch/arm/mach-at91/at91sam926x_time.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/mach-at91/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c
> index 0f04ffe9c5a8..f060f6371392 100644
> --- a/arch/arm/mach-at91/at91sam926x_time.c
> +++ b/arch/arm/mach-at91/at91sam926x_time.c
> @@ -250,6 +250,8 @@ void __init at91sam926x_pit_init(void)
>   	if (IS_ERR(mck))
>   		panic("AT91: PIT: Unable to get mck clk\n");
>   	pit_rate = clk_get_rate(mck) / 16;
> +	if (pit_rate == 0)
> +		panic("AT91: PIT: can't continue, mck rate is zero\n");
You're testing pit_rate why not printing:

"AT91: PIT: can't continue, *pit* rate is zero\n"


Otherwise,

Acked-by: Boris BREZILLON <b.brezillon.dev@gmail.com>
>   	pit_cycle = (pit_rate + HZ/2) / HZ;
>   	WARN_ON(((pit_cycle - 1) & ~AT91_PIT_PIV) != 0);
>   

[PATCH] ARM: at91: panic when the mck rate is zero

[Alexandre Belloni]

On 20/03/2014 at 17:34:09 +0100, Boris BREZILLON wrote :
> Le 20/03/2014 17:14, Alexandre Belloni a ?crit :
> >If the mck rate is zero, we'll hit the following warning:
> >
> >WARNING: CPU: 0 PID: 0 at arch/arm/mach-at91/at91sam926x_time.c:257 at91sam926x_pit_init+0x13c/0x260()
> >
> >But the kernel will continue to try booting and face a lot of divisions by zero
> >when trying to handle the various clocks.
> >
> >Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> >---
> >  arch/arm/mach-at91/at91sam926x_time.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> >diff --git a/arch/arm/mach-at91/at91sam926x_time.c b/arch/arm/mach-at91/at91sam926x_time.c
> >index 0f04ffe9c5a8..f060f6371392 100644
> >--- a/arch/arm/mach-at91/at91sam926x_time.c
> >+++ b/arch/arm/mach-at91/at91sam926x_time.c
> >@@ -250,6 +250,8 @@ void __init at91sam926x_pit_init(void)
> >  	if (IS_ERR(mck))
> >  		panic("AT91: PIT: Unable to get mck clk\n");
> >  	pit_rate = clk_get_rate(mck) / 16;
> >+	if (pit_rate == 0)
> >+		panic("AT91: PIT: can't continue, mck rate is zero\n");
> You're testing pit_rate why not printing:
> 
> "AT91: PIT: can't continue, *pit* rate is zero\n"
> 

pit_rate is zero because mck is zero I just didn't want to introduce a
new variable or another call to clk_get_rate(mck). I don't have any
strong opinion about that either so I can definitely make that change.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com