Re: [PATCH] clk: at91: generated: Truncate divisor to GENERATED_MAX_DIV + 1

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:

quoted

From: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>

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 <codrin.ciubotariu@microchip.com>

Yes:
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>

Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

Thanks

Ludovic

Thanks for having fixed this Codrin. Best regards,
   Nicolas

quoted

---
  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

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