From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Date: Sun, 20 Dec 2015 10:33:33 +0000 Subject: Re: [PATCH 4/5] fbdev: omap2: panel-dpi: allow specification of a reset gpio Message-Id: <20151220103333.GF28361@pengutronix.de> List-Id: References: <1449753107-11410-1-git-send-email-uwe@kleine-koenig.org> <1449753107-11410-4-git-send-email-uwe@kleine-koenig.org> <5671A0E2.7000909@ti.com> In-Reply-To: <5671A0E2.7000909-l0cyMroinI0@public.gmane.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Tomi Valkeinen Cc: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Jean-Christophe Plagniol-Villard , linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [Cc +=3D devicetree@vger.kernel.org] Hello Tomi, On Wed, Dec 16, 2015 at 07:35:30PM +0200, Tomi Valkeinen wrote: >=20 > On 10/12/15 15:11, Uwe Kleine-K=F6nig wrote: > > From: Uwe Kleine-K=F6nig > >=20 > > Some displays have a reset input. To assert that the display is > > functional the reset gpio must be deasserted. > >=20 > > Teach the driver to get and drive such a gpio accordingly. > >=20 > > Signed-off-by: Uwe Kleine-K=F6nig > > --- > > Documentation/devicetree/bindings/video/panel-dpi.txt | 1 + > > drivers/video/fbdev/omap2/displays-new/panel-dpi.c | 7 +++++++ > > 2 files changed, 8 insertions(+) >=20 > DT changes should be posted to devicetree@vger.kernel.org. And, I think, > the binding document changes are usually as a separate patch. Right for devicetree@vger.kernel.org, but separate patches for bindings is news to me. Anyhow, I can split this off if you prefer. > > diff --git a/Documentation/devicetree/bindings/video/panel-dpi.txt b/Do= cumentation/devicetree/bindings/video/panel-dpi.txt > > index a40180b05bab..1a1d8f6f884f 100644 > > --- a/Documentation/devicetree/bindings/video/panel-dpi.txt > > +++ b/Documentation/devicetree/bindings/video/panel-dpi.txt > > @@ -7,6 +7,7 @@ Required properties: > > Optional properties: > > - label: a symbolic name for the panel > > - enable-gpios: panel enable gpio > > +- reset-gpios: GPIO to control the RESET pin > > =20 > > Required nodes: > > - "panel-timing" containing video timings > > diff --git a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c b/drive= rs/video/fbdev/omap2/displays-new/panel-dpi.c > > index 1216341a0d19..7e2f9e0813dc 100644 > > --- a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c > > +++ b/drivers/video/fbdev/omap2/displays-new/panel-dpi.c > > @@ -32,6 +32,7 @@ struct panel_drv_data { > > int backlight_gpio; > > =20 > > struct gpio_desc *enable_gpio; > > + struct gpio_desc *reset_gpio; > > }; > > =20 > > #define to_panel_data(p) container_of(p, struct panel_drv_data, dssdev) > > @@ -83,6 +84,7 @@ static int panel_dpi_enable(struct omap_dss_device *d= ssdev) > > if (r) > > return r; > > =20 > > + gpiod_set_value_cansleep(ddata->reset_gpio, 0); > > gpiod_set_value_cansleep(ddata->enable_gpio, 1); > > =20 > > if (gpio_is_valid(ddata->backlight_gpio)) > > @@ -211,6 +213,11 @@ static int panel_dpi_probe_of(struct platform_devi= ce *pdev) > > if (IS_ERR(ddata->enable_gpio)) > > return PTR_ERR(ddata->enable_gpio); > > =20 > > + ddata->reset_gpio =3D devm_gpiod_get_optional(&pdev->dev, > > + "reset", GPIOD_OUT_HIGH); > > + if (IS_ERR(ddata->reset_gpio)) > > + return PTR_ERR(ddata->reset_gpio); > > + > > ddata->backlight_gpio =3D -ENOENT; > > =20 > > r =3D of_get_display_timing(node, "panel-timing", &timing); > >=20 >=20 > This looks a bit odd to me. This only ever sets the reset gpio to 0, on > panel enable. If we never toggle the reset, it could be set to 0 at > probe time, right? >=20 > Reset is a bit tricky. I've seen panels where you have to have only a > short reset pulse (reset high, wait a short time, reset low). If you > leave the reset high, the panel draws extra power. >=20 > So I think the best we can do in a generic way is just to ensure the > reset is not asserted. Good idea, will implement this in v2. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig | Industrial Linux Solutions | http://www.pengutronix.de/ |