From mboxrd@z Thu Jan 1 00:00:00 1970 From: gregory.clement@bootlin.com (Gregory CLEMENT) Date: Mon, 05 Mar 2018 17:22:53 +0100 Subject: [PATCH 1/2] ARM: dts: armada388-clearfog: increase speed of i2c0 to 400kHz In-Reply-To: <20180305160929.GG9418@n2100.armlinux.org.uk> (Russell King's message of "Mon, 5 Mar 2018 16:09:30 +0000") References: <20180227160135.GU9418@n2100.armlinux.org.uk> <87d10i5xqx.fsf@bootlin.com> <20180305160929.GG9418@n2100.armlinux.org.uk> Message-ID: <878tb65w6a.fsf@bootlin.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Russell King, On lun., mars 05 2018, Russell King - ARM Linux wrote: > On Mon, Mar 05, 2018 at 04:48:54PM +0100, Gregory CLEMENT wrote: >> Hi Russell, >> >> On mar., f?vr. 27 2018, Russell King wrote: >> >> > All the devices on I2C0 support fast mode, so increase the bus speed >> > to match. >> >> I agree with this part. I didn't pay attention to it in the initial >> submission but now I've checked it, and indeed according to the >> datasheet the MCP3021 support "standard (100 kHz) and Fast (400 kHz) I2C >> Compatible modes" >> >> > The Armada 388 is known to have a timing issue when in >> > standard mode, which we believe causes the ficticious device at 0x64 >> > to appear. >> >> This errata "FE-8471889 I2C Repeated Start is not supported in standard >> mode (up to 100K)" was supposed to be fixed with the commit c1d15b68aab8 >> ("i2c: mv64xxx: Fix timing issue on Armada XP (errata FE-8471889)"). And >> it was used on the Armada 38x SoCs since fbffee74986c ("ARM: dts: Fix I2C >> repeated start issue on Armada-38x") in 4.14. > > The commit pre-dates 4.14, and the commit message was correct at the time > it was committed (Nov 29 2016). I don't know whether its still the case > that the ficticious device still appears, but increasing the bus speed is > still a sensible thing to do if the devices all support it. I agree to apply it. I was concerned by the fact that the i2c fix might not work. I've just tested it and by using the "marvell,mv78230-a0-i2c" there was no more ficticious device at 100KHz, so I am happy with it. In order to make know that now the Standard mode is working on Armada 38x, I will just add a the following comment to your commit log: [gregory.clement at bootlin.com: Note that since the commit fbffee74986c ("ARM: dts: Fix I2C repeated start issue on Armada-38x") in 4.14, the timing issue is managed for the Armada 38x SoCs.] Thanks, Gregory > >> So I think that now even at 100kHz the ficticious device should not >> appear any more. If it is still the case then there might be an issue >> with the fix in the 2c driver. >> >> Gregory >> >> > >> > Signed-off-by: Russell King >> > --- >> > arch/arm/boot/dts/armada-388-clearfog.dtsi | 7 ++----- >> > 1 file changed, 2 insertions(+), 5 deletions(-) >> > >> > diff --git a/arch/arm/boot/dts/armada-388-clearfog.dtsi b/arch/arm/boot/dts/armada-388-clearfog.dtsi >> > index 68acfc968706..0e3b1f140e6d 100644 >> > --- a/arch/arm/boot/dts/armada-388-clearfog.dtsi >> > +++ b/arch/arm/boot/dts/armada-388-clearfog.dtsi >> > @@ -143,8 +143,7 @@ >> > }; >> > >> > &i2c0 { >> > - /* Is there anything on this? */ >> > - clock-frequency = <100000>; >> > + clock-frequency = <400000>; >> > pinctrl-0 = <&i2c0_pins>; >> > pinctrl-names = "default"; >> > status = "okay"; >> > @@ -239,13 +238,11 @@ >> > }; >> > }; >> > >> > - /* The MCP3021 is 100kHz clock only */ >> > + /* The MCP3021 supports standard and fast modes */ >> > mikrobus_adc: mcp3021 at 4c { >> > compatible = "microchip,mcp3021"; >> > reg = <0x4c>; >> > }; >> > - >> > - /* Also something at 0x64 */ >> > }; >> > >> > &i2c1 { >> > -- >> > 2.7.4 >> > >> >> -- >> Gregory Clement, Bootlin (formerly Free Electrons) >> Embedded Linux and Kernel engineering >> http://bootlin.com > > -- > RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up > According to speedtest.net: 8.21Mbps down 510kbps up -- Gregory Clement, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering http://bootlin.com From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory CLEMENT Subject: Re: [PATCH 1/2] ARM: dts: armada388-clearfog: increase speed of i2c0 to 400kHz Date: Mon, 05 Mar 2018 17:22:53 +0100 Message-ID: <878tb65w6a.fsf@bootlin.com> References: <20180227160135.GU9418@n2100.armlinux.org.uk> <87d10i5xqx.fsf@bootlin.com> <20180305160929.GG9418@n2100.armlinux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20180305160929.GG9418@n2100.armlinux.org.uk> (Russell King's message of "Mon, 5 Mar 2018 16:09:30 +0000") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Russell King - ARM Linux Cc: Mark Rutland , Andrew Lunn , Jason Cooper , devicetree@vger.kernel.org, Rob Herring , Gregory Clement , linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth List-Id: devicetree@vger.kernel.org SGkgUnVzc2VsbCBLaW5nLAogCiBPbiBsdW4uLCBtYXJzIDA1IDIwMTgsIFJ1c3NlbGwgS2luZyAt IEFSTSBMaW51eCA8bGludXhAYXJtbGludXgub3JnLnVrPiB3cm90ZToKCj4gT24gTW9uLCBNYXIg MDUsIDIwMTggYXQgMDQ6NDg6NTRQTSArMDEwMCwgR3JlZ29yeSBDTEVNRU5UIHdyb3RlOgo+PiBI aSBSdXNzZWxsLAo+PiAgCj4+ICBPbiBtYXIuLCBmw6l2ci4gMjcgMjAxOCwgUnVzc2VsbCBLaW5n IDxybWsra2VybmVsQGFybWxpbnV4Lm9yZy51az4gd3JvdGU6Cj4+IAo+PiA+IEFsbCB0aGUgZGV2 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