From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Date: Fri, 26 Feb 2016 12:10:08 +0000 Subject: Re: [PATCH v2 3/3] fbdev: omap2: panel-dpi: implement support for a vcc regulator Message-Id: <20160226121008.GV15189@pengutronix.de> List-Id: References: <1450610002-10531-4-git-send-email-u.kleine-koenig@pengutronix.de> In-Reply-To: <1450610002-10531-4-git-send-email-u.kleine-koenig@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: linux-fbdev@vger.kernel.org Hello, Cc +=3D Liam Girdwood, Mark Brown On Fri, Feb 26, 2016 at 12:13:07PM +0200, Tomi Valkeinen wrote: > On 16/02/16 15:48, Uwe Kleine-K=F6nig wrote: > > Hello Tomi, > >=20 > > On Tue, Feb 16, 2016 at 03:00:00PM +0200, Tomi Valkeinen wrote: > >> On 20/12/15 13:13, Uwe Kleine-K=F6nig wrote: > >>> @@ -223,6 +232,10 @@ static int panel_dpi_probe_of(struct platform_de= vice *pdev) > >>> if (IS_ERR(gpio)) > >>> return PTR_ERR(gpio); > >>> =20 > >>> + ddata->vcc_supply =3D devm_regulator_get(&pdev->dev, "vcc"); > >>> + if (IS_ERR(ddata->vcc_supply)) > >>> + return PTR_ERR(ddata->vcc_supply); > >> > >> devm_regulator_get_optional()? > >=20 > > That would make the specification of a vcc supply obligatory IIUC. (Yes, > > the semantic difference between regulator_get vs. regulator_get_optional > > is reversed when comparing to gpio_get vs. gpio_get_optional.) >=20 > This is a bit confusing... >=20 > So, is regulator_get_optional() meant for cases where the device can > truly function without the supply in question? And regulator_get() > should be used when the device needs the supply, even if the supply > cannot be controlled via SW, and thus we may not even have the supply > visible in the SW side (leading to using dummy regulator)? Yeah, I think this is the right picture. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig | Industrial Linux Solutions | http://www.pengutronix.de/ |