[PATCH v2 2/4] clk: qcom: clk-rcg2: Make sure to not write d=0 to the NMD register

From: Nikita Travkin <nikita@trvn.ru>
To: mturquette@baylibre.com, sboyd@kernel.org, linus.walleij@linaro.org
Cc: bjorn.andersson@linaro.org, agross@kernel.org,
	tdas@codeaurora.org, joonwoop@codeaurora.org,
	svarbanov@mm-sol.com, linux-arm-msm@vger.kernel.org,
	linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	~postmarketos/upstreaming@lists.sr.ht,
	Nikita Travkin <nikita@trvn.ru>
Subject: [PATCH v2 2/4] clk: qcom: clk-rcg2: Make sure to not write d=0 to the NMD register
Date: Sun, 12 Jun 2022 19:59:53 +0500	[thread overview]
Message-ID: <20220612145955.385787-3-nikita@trvn.ru> (raw)
In-Reply-To: <20220612145955.385787-1-nikita@trvn.ru>

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>

---
v2:
 - Use clamp()
---
 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;
-- 
2.35.3

