From b05d39466ba111fc3775d5d46180b73c34ebe8f7 Mon Sep 17 00:00:00 2001
From: Bjorn Andersson <quic_bjorande@quicinc.com>
Date: Mon, 15 May 2023 09:26:04 -0700
Subject: [PATCH] leds: qcom-lpg: Fix PWM period limits
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@linaro.org>
Tested-by: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Acked-by: Lee Jones <lee@kernel.org>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD
Link: https://lore.kernel.org/r/20230515162604.649203-1-quic_bjorande@quicinc.com
Signed-off-by: Johan Hovold <johan@kernel.org>
---
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 55a037234df1b..1c849814a4917 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;
--
2.30.2