pwm: Make .get_state() callback return an error code

[ Upstream commit 6c452cff79f8bf1c0146fda598d32061cfd25443 ]

.get_state() might fail in some cases. To make it possible that a driver
signals such a failure change the prototype of .get_state() to return an
error code.

This patch was created using coccinelle and the following semantic patch:

@p1@
identifier getstatefunc;
identifier driver;
@@
 struct pwm_ops driver = {
        ...,
        .get_state = getstatefunc
        ,...
 };

@p2@
identifier p1.getstatefunc;
identifier chip, pwm, state;
@@
-void
+int
 getstatefunc(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state)
 {
   ...
-  return;
+  return 0;
   ...
 }

plus the actual change of the prototype in include/linux/pwm.h (plus some
manual fixing of indentions and empty lines).

So for now all drivers return success unconditionally. They are adapted
in the following patches to make the changes easier reviewable.

Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Acked-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221130152148.2769768-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Stable-dep-of: 6f5793798014 ("pwm: hibvt: Explicitly set .polarity in .get_state()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 8 insertions, 6 deletions

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index eb24322df721..aeca9c066bf2 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -1500,8 +1500,8 @@ out:
 	return ret;
 }
 
-static void ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				struct pwm_state *state)
+static int ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			       struct pwm_state *state)
 {
 	struct ti_sn65dsi86 *pdata = pwm_chip_to_ti_sn_bridge(chip);
 	unsigned int pwm_en_inv;
@@ -1512,19 +1512,19 @@ static void ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	ret = regmap_read(pdata->regmap, SN_PWM_EN_INV_REG, &pwm_en_inv);
 	if (ret)
-		return;
+		return 0;
 
 	ret = ti_sn65dsi86_read_u16(pdata, SN_BACKLIGHT_SCALE_REG, &scale);
 	if (ret)
-		return;
+		return 0;
 
 	ret = ti_sn65dsi86_read_u16(pdata, SN_BACKLIGHT_REG, &backlight);
 	if (ret)
-		return;
+		return 0;
 
 	ret = regmap_read(pdata->regmap, SN_PWM_PRE_DIV_REG, &pre_div);
 	if (ret)
-		return;
+		return 0;
 
 	state->enabled = FIELD_GET(SN_PWM_EN_MASK, pwm_en_inv);
 	if (FIELD_GET(SN_PWM_INV_MASK, pwm_en_inv))
@@ -1539,6 +1539,8 @@ static void ti_sn_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	if (state->duty_cycle > state->period)
 		state->duty_cycle = state->period;
+
+	return 0;
 }
 
 static const struct pwm_ops ti_sn_pwm_ops = {