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SubjectRe: [PATCH] backlight: add regulator support for platform_lcd driver
Hi,

On Mon, Dec 05, 2011 at 02:18:41PM +0530, Thomas Abraham wrote:
> The power source to the lcd panel or the lcd interface such as lvds
> transmitters could be controlled by a regulator supply. Add support
> for enabling/disabling the regulator when switching power to lcd.
>
> Two new elements 'min_uV' and 'max_uV' in the platform data are added
> to allow platform code to specifiy the desired output voltage from the
> regulator.
>
> Cc: Ben Dooks <ben-linux@fluff.org>
> Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
> ---
> drivers/video/backlight/platform_lcd.c | 29 +++++++++++++++++++++++++++++
> include/video/platform_lcd.h | 7 +++++++
> 2 files changed, 36 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/video/backlight/platform_lcd.c b/drivers/video/backlight/platform_lcd.c
> index 302330a..ffa8108 100644
> --- a/drivers/video/backlight/platform_lcd.c
> +++ b/drivers/video/backlight/platform_lcd.c
> @@ -17,6 +17,8 @@
> #include <linux/backlight.h>
> #include <linux/lcd.h>
> #include <linux/slab.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/regulator/machine.h>
>
> #include <video/platform_lcd.h>
>
> @@ -44,11 +46,38 @@ static int platform_lcd_get_power(struct lcd_device *lcd)
> static int platform_lcd_set_power(struct lcd_device *lcd, int power)
> {
> struct platform_lcd *plcd = to_our_lcd(lcd);
> + struct regulator *lcd_regulator;
> int lcd_power = 1;
>
> if (power == FB_BLANK_POWERDOWN || plcd->suspended)
> lcd_power = 0;
>
> + /*
> + * If power to lcd and/or lcd interface is controlled using a regulator,
> + * enable or disable the regulator based in the power setting.
> + */
> + lcd_regulator = regulator_get(plcd->us, "vcc_lcd");
> + if (IS_ERR(lcd_regulator)) {
> + dev_info(plcd->us, "could not get regulator\n");
> + goto set_power;
> + }
> +
> + if (lcd_power) {
> + if (plcd->pdata->min_uV || plcd->pdata->max_uV)
> + if (regulator_set_voltage(lcd_regulator,
> + plcd->pdata->min_uV, plcd->pdata->max_uV))
> + dev_info(plcd->us,
> + "regulator voltage set failed\n");
> +
> + if (regulator_enable(lcd_regulator))
> + dev_info(plcd->us, "failed to enable regulator\n");
> + } else {
> + regulator_disable(lcd_regulator);
> + }
> +
> + regulator_put(lcd_regulator);

I wonder why you ->get() and ->put() everytime here. Wouldn't it be
enough to ->get() on probe() and ->put() on remove() ??

--
balbi
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