Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753609AbaJMT0n (ORCPT ); Mon, 13 Oct 2014 15:26:43 -0400 Received: from bear.ext.ti.com ([192.94.94.41]:37118 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752116AbaJMT0l (ORCPT ); Mon, 13 Oct 2014 15:26:41 -0400 Date: Mon, 13 Oct 2014 14:26:32 -0500 From: Felipe Balbi To: David Cohen CC: Felipe Balbi , , , , Subject: Re: [PATCH] pinctrl: baytrail: show output gpio state correctly on Intel Baytrail Message-ID: <20141013192632.GC29810@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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="vOmOzSkFvhd7u8Ms" Content-Disposition: inline In-Reply-To: <20141013192404.GB4034@psi-dev26.jf.intel.com> 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 --vOmOzSkFvhd7u8Ms Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, 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 read = 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 gp= io. > > > 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/pin= ctrl-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 gpio_= 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 very > > 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/pinct= rl-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_chi= p *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_ch= ip *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. 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. --=20 balbi --vOmOzSkFvhd7u8Ms Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUPCdoAAoJEIaOsuA1yqRE6V4QAJrDdR8OCm+lsv/ZLT2gmDVF 1c9P92J5bLiwfQxwjGrFdyBklZ0mFI/4cohFJE+oSLsZ4N0myaAJbaeM8WT0PjBX 8szRZpNmypwjrbGp9qU3tCsOxFCdDU2wQz++y4Nwr6GxOxAtXDn8bIe0Z9MSJA7v JHTWnf43r6qQ5KhKdtyPjyJrh91WnC3rnBgllJKKZb5SCrVb1WR9fNPC1GuN6gJQ 3LRkcVbEj88QhQsL0pp0jv5Ee8j9sW5/V7cUi8Y96JNnuBQ3o6KQhxze/LB3wbl3 2pzCCFz488PXbAtzLWHboT6MRKJquimjcYhTemYTaH5AqcX+YdDPgt3tkPr1E3aR qc5QDXJyL+agzZ3iBfySBoD1CevKd9heVI3r0bLt+GvsYkxHVARUHnVZ6JYnl8Vq LkfR8ShAFwuU6gA1JhjVIC0SBQzWvPgZFt6KOZ/HiIp1Vk5AhdGknfxK8H+Lc1C/ HYHHRVB7zT5w2M+YwIk9Br8t7HswwC0sG2IpqpHrlImps3q7/uOBUDF/h6cwkpr+ jkk3PglSRYTLYpSr2vvvxhU5fd+OQLDAom9OPhm3GMPG+ugaiSCV9CxpemgNktTQ 1XOkijEo+417dGpJ8EMvr7HtCNi3tMY7pbjRmI/uA+rxwq3560KRvQVWwDdSLauB 6umnGkhLAM0TE2i4IM86 =UJ+x -----END PGP SIGNATURE----- --vOmOzSkFvhd7u8Ms-- -- 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/