From: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
To: "Henrik Nordström"
<henrik-N0bZODiMPoV/1Aw6q1k8hdHuzzzSOjJt@public.gmane.org>
Cc: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org,
Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>,
Jason Cooper <jason-NLaQJdtUoK4Be96aLqz0jA@public.gmane.org>,
Andrew Lunn <andrew-g2DYL2Zd6BY@public.gmane.org>,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Emilio Lopez <emilio-0Z03zUJReD5OxF6Tv1QG9Q@public.gmane.org>,
kevin-0TFLnhJekD6UEPyfVivIlAC/G2K4zDHf@public.gmane.org,
sunny-0TFLnhJekD6UEPyfVivIlAC/G2K4zDHf@public.gmane.org,
shuge-0TFLnhJekD6UEPyfVivIlAC/G2K4zDHf@public.gmane.org,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Tomasz Figa <tomasz.figa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCHv4 7/9] ARM: sun5i: dt: Add i2c muxing options
Date: Wed, 12 Jun 2013 13:20:21 +0200 [thread overview]
Message-ID: <20130612112021.GC16699@lukather> (raw)
In-Reply-To: <1371025788.4659.20.camel@localhost>
Hi Henrik,
On Wed, Jun 12, 2013 at 10:29:48AM +0200, Henrik Nordström wrote:
> ons 2013-06-12 klockan 10:07 +0200 skrev Maxime Ripard:
>
> > + i2c0_pins_a: i2c0@0 {
> > + allwinner,pins = "PB0", "PB1";
> > + allwinner,function = "i2c0";
> > + allwinner,drive = <0>;
> > + allwinner,pull = <0>;
>
> Is this right? All other use pull = 1.
Ah, true.
> I guess it's board dependent depending on if there is external pullups
> or not on the i2c bus. I have seen Allwinner designs both with and
> without external pullups.
>
> It will not work well if there is neither internal or external pullup.
> And may stress the i2c components a bit if there is both..
Yes, but it's a default, so by definition, it won't suit everyone. Yet,
it has to be there. And every board is free to override that default in
its own DT anyway, so it's not really a big issue. But like you pointed
at, we have to be consistent.
I'll disable the pull-ups in the next iteration for every node.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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WARNING: multiple messages have this Message-ID (diff)
From: maxime.ripard@free-electrons.com (Maxime Ripard)
To: linux-arm-kernel@lists.infradead.org
Subject: [linux-sunxi] [PATCHv4 7/9] ARM: sun5i: dt: Add i2c muxing options
Date: Wed, 12 Jun 2013 13:20:21 +0200 [thread overview]
Message-ID: <20130612112021.GC16699@lukather> (raw)
In-Reply-To: <1371025788.4659.20.camel@localhost>
Hi Henrik,
On Wed, Jun 12, 2013 at 10:29:48AM +0200, Henrik Nordstr?m wrote:
> ons 2013-06-12 klockan 10:07 +0200 skrev Maxime Ripard:
>
> > + i2c0_pins_a: i2c0 at 0 {
> > + allwinner,pins = "PB0", "PB1";
> > + allwinner,function = "i2c0";
> > + allwinner,drive = <0>;
> > + allwinner,pull = <0>;
>
> Is this right? All other use pull = 1.
Ah, true.
> I guess it's board dependent depending on if there is external pullups
> or not on the i2c bus. I have seen Allwinner designs both with and
> without external pullups.
>
> It will not work well if there is neither internal or external pullup.
> And may stress the i2c components a bit if there is both..
Yes, but it's a default, so by definition, it won't suit everyone. Yet,
it has to be there. And every board is free to override that default in
its own DT anyway, so it's not really a big issue. But like you pointed
at, we have to be consistent.
I'll disable the pull-ups in the next iteration for every node.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2013-06-12 11:20 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-12 8:07 [PATCHv4 0/9] Add I2C support for Allwinner SoCs Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
[not found] ` <1371024438-16631-1-git-send-email-maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2013-06-12 8:07 ` [PATCHv4 1/9] i2c: mv64xxx: Add macros to access parts of registers Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
2013-06-12 8:07 ` [PATCHv4 2/9] i2c: mv64xxx: make the registers offset configurable Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
2013-06-12 10:54 ` Andrew Lunn
2013-06-12 10:54 ` Andrew Lunn
[not found] ` <20130612105431.GS16502-g2DYL2Zd6BY@public.gmane.org>
2013-06-12 11:29 ` Maxime Ripard
2013-06-12 11:29 ` Maxime Ripard
[not found] ` <1371024438-16631-3-git-send-email-maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2013-06-12 13:57 ` Russell King - ARM Linux
2013-06-12 13:57 ` Russell King - ARM Linux
[not found] ` <20130612135735.GR18614-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2013-06-12 14:44 ` Maxime Ripard
2013-06-12 14:44 ` Maxime Ripard
2013-06-12 14:51 ` Russell King - ARM Linux
2013-06-12 14:51 ` Russell King - ARM Linux
[not found] ` <20130612145139.GS18614-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2013-06-12 15:17 ` Maxime Ripard
2013-06-12 15:17 ` Maxime Ripard
2013-06-12 15:03 ` Sebastian Hesselbarth
2013-06-12 15:03 ` Sebastian Hesselbarth
[not found] ` <51B88DB0.90302-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-06-12 15:37 ` Maxime Ripard
2013-06-12 15:37 ` Maxime Ripard
2013-06-12 8:07 ` [PATCHv4 3/9] ARM: orion: pass the i2c registers definition through the platform data Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
[not found] ` <1371024438-16631-4-git-send-email-maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2013-06-12 8:39 ` Tomasz Figa
2013-06-12 8:39 ` Tomasz Figa
2013-06-12 8:07 ` [PATCHv4 4/9] i2c: mv64xxx: Add Allwinner sun4i compatible Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
[not found] ` <1371024438-16631-5-git-send-email-maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2013-06-12 8:42 ` Tomasz Figa
2013-06-12 8:42 ` Tomasz Figa
2013-06-12 11:27 ` Maxime Ripard
2013-06-12 11:27 ` Maxime Ripard
2013-06-12 10:56 ` Andrew Lunn
2013-06-12 10:56 ` Andrew Lunn
[not found] ` <20130612105613.GT16502-g2DYL2Zd6BY@public.gmane.org>
2013-06-12 11:31 ` Maxime Ripard
2013-06-12 11:31 ` Maxime Ripard
2013-06-12 8:07 ` [PATCHv4 5/9] ARM: sunxi: dt: Add i2c controller nodes to the DTSI Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
2013-06-12 8:07 ` [PATCHv4 6/9] ARM: sun4i: dt: Add i2c muxing options Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
2013-06-12 8:07 ` [PATCHv4 7/9] ARM: sun5i: " Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
[not found] ` <1371024438-16631-8-git-send-email-maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2013-06-12 8:29 ` Henrik Nordström
2013-06-12 8:29 ` [linux-sunxi] " Henrik Nordström
2013-06-12 11:20 ` Maxime Ripard [this message]
2013-06-12 11:20 ` Maxime Ripard
2013-06-12 8:07 ` [PATCHv4 8/9] ARM: sun5i: olinuxino: Enable the i2c controllers Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
2013-06-12 8:07 ` [PATCHv4 9/9] ARM: sun4i: cubieboard: " Maxime Ripard
2013-06-12 8:07 ` Maxime Ripard
2013-06-12 11:26 ` [PATCHv4 0/9] Add I2C support for Allwinner SoCs Arnd Bergmann
2013-06-12 11:26 ` Arnd Bergmann
2013-06-12 11:38 ` Maxime Ripard
2013-06-12 11:38 ` Maxime Ripard
2013-06-12 12:38 ` Arnd Bergmann
2013-06-12 12:38 ` Arnd Bergmann
[not found] ` <201306121438.12549.arnd-r2nGTMty4D4@public.gmane.org>
2013-06-12 12:44 ` Maxime Ripard
2013-06-12 12:44 ` Maxime Ripard
2013-06-14 14:01 ` Wolfram Sang
2013-06-14 14:01 ` Wolfram Sang
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