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    Subject[PATCH 5.19 0762/1157] clk: qcom: clk-rcg2: Make sure to not write d=0 to the NMD register
    Date
    From: Nikita Travkin <nikita@trvn.ru>

    [ Upstream commit d0696770cef35a1fd16ea2167e2198c18aa6fbfe ]

    Sometimes calculation of d value may result in 0 because of the
    rounding after integer division. This causes the following error:

    [ 113.969689] camss_gp1_clk_src: rcg didn't update its configuration.
    [ 113.969754] WARNING: CPU: 3 PID: 35 at drivers/clk/qcom/clk-rcg2.c:122 update_config+0xc8/0xdc

    Make sure that D value is never zero.

    Fixes: 7f891faf596e ("clk: qcom: clk-rcg2: Add support for duty-cycle for RCG")
    Signed-off-by: Nikita Travkin <nikita@trvn.ru>
    Reviewed-by: Stephen Boyd <sboyd@kernel.org>
    Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
    Link: https://lore.kernel.org/r/20220612145955.385787-3-nikita@trvn.ru
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/clk/qcom/clk-rcg2.c | 9 ++++++---
    1 file changed, 6 insertions(+), 3 deletions(-)

    diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
    index 2375e8122012..28019edd2a50 100644
    --- a/drivers/clk/qcom/clk-rcg2.c
    +++ b/drivers/clk/qcom/clk-rcg2.c
    @@ -13,6 +13,7 @@
    #include <linux/rational.h>
    #include <linux/regmap.h>
    #include <linux/math64.h>
    +#include <linux/minmax.h>
    #include <linux/slab.h>

    #include <asm/div64.h>
    @@ -461,9 +462,11 @@ static int clk_rcg2_set_duty_cycle(struct clk_hw *hw, struct clk_duty *duty)
    /* Calculate 2d value */
    d = DIV_ROUND_CLOSEST(n * duty_per * 2, 100);

    - /* Check bit widths of 2d. If D is too big reduce duty cycle. */
    - if (d > mask)
    - d = mask;
    + /*
    + * Check bit widths of 2d. If D is too big reduce duty cycle.
    + * Also make sure it is never zero.
    + */
    + d = clamp_val(d, 1, mask);

    if ((d / 2) > (n - m))
    d = (n - m) * 2;
    --
    2.35.1


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