Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753477AbaJMTg1 (ORCPT ); Mon, 13 Oct 2014 15:36:27 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:48451 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753170AbaJMTgZ (ORCPT ); Mon, 13 Oct 2014 15:36:25 -0400 Date: Mon, 13 Oct 2014 14:36:18 -0500 From: Felipe Balbi To: Felipe Balbi CC: David Cohen , , , , Subject: Re: [PATCH] pinctrl: baytrail: show output gpio state correctly on Intel Baytrail Message-ID: <20141013193618.GD29810@saruman> Reply-To: References: <1412355319-18946-1-git-send-email-david.a.cohen@linux.intel.com> <1413224639-21552-1-git-send-email-david.a.cohen@linux.intel.com> <20141013191405.GB29810@saruman> <20141013192404.GB4034@psi-dev26.jf.intel.com> <20141013192632.GC29810@saruman> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="uxuisgdDHaNETlh8" Content-Disposition: inline In-Reply-To: <20141013192632.GC29810@saruman> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --uxuisgdDHaNETlh8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 13, 2014 at 02:26:32PM -0500, Felipe Balbi wrote: > Hi, >=20 > On Mon, Oct 13, 2014 at 12:24:04PM -0700, David Cohen wrote: > > On Mon, Oct 13, 2014 at 02:14:05PM -0500, Felipe Balbi wrote: > > > On Mon, Oct 13, 2014 at 11:23:59AM -0700, David Cohen wrote: > > > > Even if a gpio pin is set to output, we still need to set INPUT_EN = bit > > >=20 > > > here you say you're setting that bit. > > >=20 > > > > to be able to read its value. Without this change, we'll always rea= d low > > > > level state. > > > >=20 > > > > Cc: # v3.14+ > > > > Signed-off-by: David Cohen > > > > --- > > > >=20 > > > > Hi, > > > >=20 > > > > I'm resending same v1 patch but now copying linux stable and linux = gpio. > > > > This patch is meant for all linux stable trees >=3D v3.14. > > > >=20 > > > > Br, David > > > > --- > > > >=20 > > > > drivers/pinctrl/pinctrl-baytrail.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > >=20 > > > > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/p= inctrl-baytrail.c > > > > index e12e5b07f6d7..c23d8ded936d 100644 > > > > --- a/drivers/pinctrl/pinctrl-baytrail.c > > > > +++ b/drivers/pinctrl/pinctrl-baytrail.c > > > > @@ -318,7 +318,7 @@ static int byt_gpio_direction_output(struct gpi= o_chip *chip, > > > > "Potential Error: Setting GPIO with direct_irq_en to output"); > > > > =20 > > > > reg_val =3D readl(reg) | BYT_DIR_MASK; > > > > - reg_val &=3D ~BYT_OUTPUT_EN; > > > > + reg_val &=3D ~(BYT_OUTPUT_EN | BYT_INPUT_EN); > > >=20 > > > but code is clearing it. Also, you're not patching byt_gpio_get(), so > > > you can't be 'reading its value' either. Quite frankly, this looks ve= ry > > > fishy to me. Comments on BYT_OUTPUT_EN and BYT_INPUT_EN states that > > > those bits are active low, meaning that clearing them enables that > > > particular feature. > > >=20 > > > How can you enable a pin to be both OUTPUT and INPUT ? Look like what > > > you really want is: > > >=20 > > > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pin= ctrl-baytrail.c > > > index e12e5b0..69f882d 100644 > > > --- a/drivers/pinctrl/pinctrl-baytrail.c > > > +++ b/drivers/pinctrl/pinctrl-baytrail.c > > > @@ -290,6 +290,7 @@ static int byt_gpio_direction_input(struct gpio_c= hip *chip, unsigned offset) > > > =20 > > > value =3D readl(reg) | BYT_DIR_MASK; > > > value &=3D ~BYT_INPUT_EN; /* active low */ > > > + value |=3D BYT_OUTPUT_EN; /* disable output */ > > > writel(value, reg); > > > =20 > > > spin_unlock_irqrestore(&vg->lock, flags); > > > @@ -319,6 +320,7 @@ static int byt_gpio_direction_output(struct gpio_= chip *chip, > > > =20 > > > reg_val =3D readl(reg) | BYT_DIR_MASK; > > > reg_val &=3D ~BYT_OUTPUT_EN; > > > + value |=3D BYT_INPUT_EN; /* disable input */ > > > =20 > > > if (value) > > > writel(reg_val | BYT_LEVEL, reg); > > >=20 > > > completely untested however. Care to further explain why clearing both > > > bits - thus enabling both INPUT and OUTPUT - is correct ? > >=20 > > Actually I really meant what I sent, but perhaps I misspoke during > > explanation. We need to clear the bit to enable the functionality. > >=20 > > !BYT_INPUT_EN allows us to read the value. !BYT_OUTPUT_EN allows us to > > set a value. If we want to set a value (acting as output) and still be > > able to read via sysfs, we need to set both functionality (i.e. clear > > both bits). > >=20 > > I'll resend the patch with a better comment. >=20 > Alright, just make sure that exposing a pin through sysfs and making it > output high, then later switching it to input works. It looks like > byt_gpio_direction_input() still needs to make sure OUTPUT is set. I also noticed that this is missing: diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-b= aytrail.c index e12e5b0..7db5ab9 100644 --- a/drivers/pinctrl/pinctrl-baytrail.c +++ b/drivers/pinctrl/pinctrl-baytrail.c @@ -614,3 +614,9 @@ static int __init byt_gpio_init(void) } =20 subsys_initcall(byt_gpio_init); + +static void __exit byt_gpio_exit(void) +{ + platform_driver_unregister(&byt_gpio_driver); +} +module_exit(byt_gpio_exit); (also untested) ps: is BayTrail documentation available publicly ? --=20 balbi --uxuisgdDHaNETlh8 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUPCmyAAoJEIaOsuA1yqREr6wQAJmkoO9EipDtd/iq4yDMDu99 MZ3llqigUFsqPF/2u+GJOutwPdCHxYvW4/BV8m/1SVXW2bxpb2sYzkO/LpZFZy3O WvxZg8bM8YPP+KQlVefF2FkVd/1S/OdajwojZ4K14wh7SkmSwqsa2ivk0yG7V02w K1OiGYiYi6jISFS/ZAYzRSPJT2htprJYylGa9vx9dYQMJZHtkuD4CUSEcEnoFubU q9MfEdKPZgDEMPSkrbBJGlzZpOJJXc6lcd3dKCQja4HwRSMlW8nhAO6fvSK+LJc8 h0Pgdg6nZxab7qSXr50q4elaXny51t3aNnlIlSk1Qdg/m4EBIMGd3XDI/KhlPTHX PTimoWnCQEaoqJ+ReynFuhOkSfTCsurlo3oTAhf+rUKfDVodwe/3YbibMH8QszcC BoT8CT9bYhJESPOPFH+aLLIU405nIfRQxzKcWN6u+5wXYQQly5y9PZXL8u4Dp+M5 frIc5b/f5A+Pglp9h+jVXCtOGu7kTlAACRya2K1IBVuLqkCFucbgbPZZ4AztpKkj BYQwqpxejwClvPuszFN2Y1bnAgtRBJsCQHcnkYAh6G3Ax7LD94DBYZdngmVnJo8M zyQFpTtDqx90Ukpy7Hxb5CR4CZM8riI1lbOOkwi1oFQWpAGOQ0cXUUawTesV3wnz 4Uxdw+80av++0Rwz+721 =49XI -----END PGP SIGNATURE----- --uxuisgdDHaNETlh8-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/