[PATCH] pwm: sun4i: Propagate errors in .get_state() to the caller

From: Andre Przywara <andre.przywara@arm.com>
To: "Thierry Reding" <thierry.reding@gmail.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Samuel Holland <samuel@sholland.org>,
	linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev
Subject: [PATCH] pwm: sun4i: Propagate errors in .get_state() to the caller
Date: Thu,  1 Dec 2022 15:22:23 +0000	[thread overview]
Message-ID: <20221201152223.3133-1-andre.przywara@arm.com> (raw)

.get_state() can return an error indication now. Make use of it to
propagate an impossible prescaler encoding, should that have sneaked in
somehow.
Also check the return value of clk_get_rate(). That's unlikely to fail,
but we use that in two divide operations down in the code, so let's
avoid a divide-by-zero condition on the way.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
Hi,

this goes on top of Uwe's series to introduce and observe .get_state
failures: https://lore.kernel.org/linux-pwm/20221130152148.2769768-12-u.kleine-koenig@pengutronix.de/T/#m9af39aa03bbd9bb7b31b3600f110c65ee0e8e70b
Actually it only relies on patch 01/11 from that.

Cheers,
Andre

 drivers/pwm/pwm-sun4i.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 37d75e252d4e..b973da73e9ab 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -118,6 +118,8 @@ static int sun4i_pwm_get_state(struct pwm_chip *chip,
 	unsigned int prescaler;
 
 	clk_rate = clk_get_rate(sun4i_pwm->clk);
+	if (!clk_rate)
+		return -EINVAL;
 
 	val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 
@@ -142,7 +144,7 @@ static int sun4i_pwm_get_state(struct pwm_chip *chip,
 		prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];
 
 	if (prescaler == 0)
-		return 0;
+		return -EINVAL;
 
 	if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
 		state->polarity = PWM_POLARITY_NORMAL;
-- 
2.17.1


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