From dc881123aa1aeff02ce2dc94c2b810d37173aa90 Mon Sep 17 00:00:00 2001
From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Date: Mon, 12 Oct 2015 15:29:03 +0300
Subject: [PATCH] backlight: pwm: Reject legacy PWM request for device defined
in DT
Platform PWM backlight data provided by board's device tree should be
complete enough to successfully request a pwm device using pwm_get()
API. This change fixes a bug, when an arbitrary (first found) PWM is
connected to a "pwm-backlight" compatible device, when explicit PWM
device reference is not given.
Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
already describes "pwms" as a required property, instead of blind
selection of a potentially wrong PWM reject legacy PWM device
registration request, leave legacy API only for non-dt cases.
Based on initial implementation done by Dmitry Eremin-Solenikov.
Reported-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
drivers/video/backlight/pwm_bl.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index eff379b234cc..ae3c6b6fd5db 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -271,19 +271,18 @@ static int pwm_backlight_probe(struct platform_device *pdev)
}
pb->pwm = devm_pwm_get(&pdev->dev, NULL);
- if (IS_ERR(pb->pwm)) {
- ret = PTR_ERR(pb->pwm);
- if (ret == -EPROBE_DEFER)
- goto err_alloc;
-
+ if (IS_ERR(pb->pwm) && PTR_ERR(pb->pwm) != -EPROBE_DEFER
+ && !pdev->dev.of_node) {
dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
pb->legacy = true;
pb->pwm = pwm_request(data->pwm_id, "pwm-backlight");
- if (IS_ERR(pb->pwm)) {
- dev_err(&pdev->dev, "unable to request legacy PWM\n");
- ret = PTR_ERR(pb->pwm);
- goto err_alloc;
- }
+ }
+
+ if (IS_ERR(pb->pwm)) {
+ ret = PTR_ERR(pb->pwm);
+ if (ret != -EPROBE_DEFER)
+ dev_err(&pdev->dev, "unable to request PWM\n");
+ goto err_alloc;
}
dev_dbg(&pdev->dev, "got pwm for backlight\n");
--
2.30.9