On 15/05/2023 18:26, Bjorn Andersson wrote:
The introduction of high resolution PWM support changed the order of the
operations in the calculation of min and max period. The result in both
divisions is in most cases a truncation to 0, which limits the period to
the range of [0, 0].
Both numerators (and denominators) are within 64 bits, so the whole
expression can be put directly into the div64_u64, instead of doing it
partially.
Fixes: b00d2ed37617 ("leds: rgb: leds-qcom-lpg: Add support for high resolution PWM")
Reviewed-by: Caleb Connolly <caleb.connolly@xxxxxxxxxx>
Tested-by: Steev Klimaszewski <steev@xxxxxxxx>
Signed-off-by: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx>
---
Changes since v1:
- Reworded first sentence to express that it's the order and not the
previously non-existent parenthesis that changed...
- Picked up review tags.
drivers/leds/rgb/leds-qcom-lpg.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/leds/rgb/leds-qcom-lpg.c b/drivers/leds/rgb/leds-qcom-lpg.c
index c9cea797a697..7287fadc00df 100644
--- a/drivers/leds/rgb/leds-qcom-lpg.c
+++ b/drivers/leds/rgb/leds-qcom-lpg.c
@@ -312,14 +312,14 @@ static int lpg_calc_freq(struct lpg_channel *chan, uint64_t period)
max_res = LPG_RESOLUTION_9BIT;
}
- min_period = (u64)NSEC_PER_SEC *
- div64_u64((1 << pwm_resolution_arr[0]), clk_rate_arr[clk_len - 1]);
+ min_period = div64_u64((u64)NSEC_PER_SEC * (1 << pwm_resolution_arr[0]),
+ clk_rate_arr[clk_len - 1]);
if (period <= min_period)
return -EINVAL;
/* Limit period to largest possible value, to avoid overflows */
- max_period = (u64)NSEC_PER_SEC * max_res * LPG_MAX_PREDIV *
- div64_u64((1 << LPG_MAX_M), 1024);
+ max_period = div64_u64((u64)NSEC_PER_SEC * max_res * LPG_MAX_PREDIV * (1 << LPG_MAX_M),
+ 1024);
if (period > max_period)
period = max_period;
Tested-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx> # on SM8550-QRD
