Commit dc881123 authored Oct 12, 2015 by Vladimir Zapolskiy Committed by Lee Jones Oct 15, 2015

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>

parent f85de2d9

drivers/video/backlight/pwm_bl.c

+9 −10

Original line number	Diff line number	Diff line
		@@ -271,20 +271,19 @@ 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);
		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");