clk: at91: generated: Truncate divisor to GENERATED_MAX_DIV + 1

Commit Message

Codrin Ciubotariu June 10, 2019, 3:20 p.m. UTC

From: Codrin Ciubotariu <[e-mail]>

In clk_generated_determine_rate(), if the divisor is greater than
GENERATED_MAX_DIV + 1, then the wrong best_rate will be returned.
If clk_generated_set_rate() will be called later with this wrong
rate, it will return -EINVAL, so the generated clock won't change
its value. Do no let the divisor be greater than GENERATED_MAX_DIV + 1.

Fixes: 8c7aa6328947 ("clk: at91: clk-generated: remove useless divisor loop")
Signed-off-by: Codrin Ciubotariu <[e-mail]>
---
 drivers/clk/at91/clk-generated.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Nicolas Ferre June 12, 2019, 1:54 p.m. UTC | #1

On 10/06/2019 at 17:20, Codrin Ciubotariu - M19940 wrote:
> From: Codrin Ciubotariu <[e-mail]>
> 
> In clk_generated_determine_rate(), if the divisor is greater than
> GENERATED_MAX_DIV + 1, then the wrong best_rate will be returned.
> If clk_generated_set_rate() will be called later with this wrong
> rate, it will return -EINVAL, so the generated clock won't change
> its value. Do no let the divisor be greater than GENERATED_MAX_DIV + 1.
> 
> Fixes: 8c7aa6328947 ("clk: at91: clk-generated: remove useless divisor loop")
> Signed-off-by: Codrin Ciubotariu <[e-mail]>

Yes:
Acked-by: Nicolas Ferre <[e-mail]>

Thanks for having fixed this Codrin. Best regards,
   Nicolas

> ---
>   drivers/clk/at91/clk-generated.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c
> index 5f18847965c1..290cffe35deb 100644
> --- a/drivers/clk/at91/clk-generated.c
> +++ b/drivers/clk/at91/clk-generated.c
> @@ -146,6 +146,8 @@ static int clk_generated_determine_rate(struct clk_hw *hw,
>   			continue;
>   
>   		div = DIV_ROUND_CLOSEST(parent_rate, req->rate);
> +		if (div > GENERATED_MAX_DIV + 1)
> +			div = GENERATED_MAX_DIV + 1;
>   
>   		clk_generated_best_diff(req, parent, parent_rate, div,
>   					&best_diff, &best_rate);
>

Ludovic Desroches June 12, 2019, 2:29 p.m. UTC | #2

On Wed, Jun 12, 2019 at 03:54:00PM +0200, Nicolas Ferre - M43238 wrote:
> On 10/06/2019 at 17:20, Codrin Ciubotariu - M19940 wrote:
> > From: Codrin Ciubotariu <[e-mail]>
> > 
> > In clk_generated_determine_rate(), if the divisor is greater than
> > GENERATED_MAX_DIV + 1, then the wrong best_rate will be returned.
> > If clk_generated_set_rate() will be called later with this wrong
> > rate, it will return -EINVAL, so the generated clock won't change
> > its value. Do no let the divisor be greater than GENERATED_MAX_DIV + 1.
> > 
> > Fixes: 8c7aa6328947 ("clk: at91: clk-generated: remove useless divisor loop")
> > Signed-off-by: Codrin Ciubotariu <[e-mail]>
> 
> Yes:
> Acked-by: Nicolas Ferre <[e-mail]>

Acked-by: Ludovic Desroches <[e-mail]>

Thanks

Ludovic

> 
> Thanks for having fixed this Codrin. Best regards,
>    Nicolas
> 
> > ---
> >   drivers/clk/at91/clk-generated.c | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c
> > index 5f18847965c1..290cffe35deb 100644
> > --- a/drivers/clk/at91/clk-generated.c
> > +++ b/drivers/clk/at91/clk-generated.c
> > @@ -146,6 +146,8 @@ static int clk_generated_determine_rate(struct clk_hw *hw,
> >   			continue;
> >   
> >   		div = DIV_ROUND_CLOSEST(parent_rate, req->rate);
> > +		if (div > GENERATED_MAX_DIV + 1)
> > +			div = GENERATED_MAX_DIV + 1;
> >   
> >   		clk_generated_best_diff(req, parent, parent_rate, div,
> >   					&best_diff, &best_rate);
> > 
> 
> 
> -- 
> Nicolas Ferre

Patch

diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c
index 5f18847965c1..290cffe35deb 100644
--- a/drivers/clk/at91/clk-generated.c
+++ b/drivers/clk/at91/clk-generated.c
@@ -146,6 +146,8 @@  static int clk_generated_determine_rate(struct clk_hw *hw,
 			continue;
 
 		div = DIV_ROUND_CLOSEST(parent_rate, req->rate);
+		if (div > GENERATED_MAX_DIV + 1)
+			div = GENERATED_MAX_DIV + 1;
 
 		clk_generated_best_diff(req, parent, parent_rate, div,
 					&best_diff, &best_rate);