Messages in this thread | | | Date | Mon, 5 Dec 2011 16:06:17 +0530 | Subject | Re: [PATCH] backlight: add regulator support for platform_lcd driver | From | Thomas Abraham <> |
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Dear Mr. Park,
On 5 December 2011 15:40, Kyungmin Park <kmpark@infradead.org> wrote: [...]
>> + /* >> + * 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; >> + } > > Recent regulator discussion. it should be failed instead fall through > gracefully.
Ok. But in this case, there could be boards that do not use a regulator for the lcd/display interface. Is it mandatory for fail if regulator is not found. Sorry, I have not read through the regulator discussion.
>> + >> + 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"); > Are there case to change the voltage? Doesn't it easy to set the > voltage at board file? I mean don't need to setup at drivers?
The constraint 'apply_uV' cannot be expressed with a device tree. So there has be a mechanism to set the required output voltage for a regulator.
In case of platform-lcd driver, the power source should be turned off to the lcd/interfaces until the display controller driver is enabled. Powering on the lcd/interfaces at boot time by default would not be ideal.
Thanks for your review and comments.
Regards, Thomas.
> > Thank you, > Kyungmin Park
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