This is a note to let you know that I've just added the patch titled clk: at91: clk-master: check if div or pres is zero to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: clk-at91-clk-master-check-if-div-or-pres-is-zero.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit ed6fc38e97cb892e09c0381a32e390ee1e011723 Author: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> Date: Mon Oct 11 14:27:12 2021 +0300 clk: at91: clk-master: check if div or pres is zero [ Upstream commit c2910c00fee4cbb7b222d6e02846adef9ae4135a ] Check if div or pres is zero before using it as argument for ffs(). In case div is zero ffs() will return 0 and thus substracting from zero will lead to invalid values to be setup in registers. Fixes: 7a110b9107ed8 ("clk: at91: clk-master: re-factor master clock") Fixes: 75c88143f3b87 ("clk: at91: clk-master: add master clock support for SAMA7G5") Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20211011112719.3951784-9-claudiu.beznea@xxxxxxxxxxxxx Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/clk/at91/clk-master.c b/drivers/clk/at91/clk-master.c index a80427980bf73..2e410815a3405 100644 --- a/drivers/clk/at91/clk-master.c +++ b/drivers/clk/at91/clk-master.c @@ -280,7 +280,7 @@ static int clk_master_pres_set_rate(struct clk_hw *hw, unsigned long rate, else if (pres == 3) pres = MASTER_PRES_MAX; - else + else if (pres) pres = ffs(pres) - 1; spin_lock_irqsave(master->lock, flags); @@ -610,7 +610,7 @@ static int clk_sama7g5_master_set_rate(struct clk_hw *hw, unsigned long rate, if (div == 3) div = MASTER_PRES_MAX; - else + else if (div) div = ffs(div) - 1; spin_lock_irqsave(master->lock, flags);