linux-kernel - Re: [PATCH] arm: dts: mt7623: enable all four available UARTs on bananapi-r2

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Date:   Fri, 9 Feb 2018 11:55:46 +0800
From:   Sean Wang <sean.wang@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>
CC:     <robh+dt@...nel.org>, <mark.rutland@....com>,
        <devicetree@...r.kernel.org>, <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm: dts: mt7623: enable all four available UARTs on
 bananapi-r2

On Wed, 2018-02-07 at 17:01 +0100, Matthias Brugger wrote:
> 
> On 01/23/2018 09:51 AM, Sean Wang wrote:
> > On Sat, 2017-12-23 at 23:35 +0800, Sean Wang wrote:
> >> On Sat, 2017-12-23 at 08:52 +0100, Matthias Brugger wrote:
> >>>
> >>> On 12/22/2017 07:06 AM, sean.wang@...iatek.com wrote:
> >>>> From: Sean Wang <sean.wang@...iatek.com>
> >>>>
> >>>> On bpi-r2 board, totally there're four uarts which we usually called
> >>>> uart[0-3] helpful to extend slow I/O devices. Among those ones, uart2 has
> >>>> dedicated pin slot which is used to conolse log. uart[0-1] appear at the
> >>>> 40-pins connector and uart3 has no pinout, but just has test points (TP47
> >>>> for TX and TP48 for RX, respectively) nearby uart2. Also, some missing
> >>>> pinctrl is being complemented for those devices.
> >>>>
> >>>> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> >>>> ---
> >>>>  arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts | 26 ++++++++++++++++++++++++--
> >>>>  1 file changed, 24 insertions(+), 2 deletions(-)
> >>>>
> >>>> diff --git a/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts b/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts
> >>>> index 7bf5aa2..64bf5db 100644
> >>>> --- a/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts
> >>>> +++ b/arch/arm/boot/dts/mt7623n-bananapi-bpi-r2.dts
> >>>> @@ -409,6 +409,20 @@
> >>>>  				 <MT7623_PIN_82_UTXD1_FUNC_UTXD1>;
> >>>>  		};do you like it or quite want me to remove the uart3 node?
> >>>>  	};
> >>>> +
> >>>> +	uart2_pins_a: uart@2 {
> >>>> +		pins_dat {
> >>>> +			pinmux = <MT7623_PIN_14_GPIO14_FUNC_URXD2>,
> >>>> +				 <MT7623_PIN_15_GPIO15_FUNC_UTXD2>;
> >>>> +		};
> >>>> +	};
> >>>> +
> >>>> +	uart3_pins_a: uart@3 {
> >>>> +		pins_dat {
> >>>> +			pinmux = <MT7623_PIN_242_URTS2_FUNC_URTS2>,
> >>>> +				 <MT7623_PIN_243_UCTS2_FUNC_UTXD3>;
> >>>> +		};
> >>>> +	};
> >>>>  };
> >>>>  
> >>>>  &pwm {
> >>>> @@ -454,16 +468,24 @@
> >>>>  &uart0 {
> >>>>  	pinctrl-names = "default";
> >>>>  	pinctrl-0 = <&uart0_pins_a>;
> >>>> -	status = "disabled";
> >>>> +	status = "okay";
> >>>>  };
> >>>>  
> >>>>  &uart1 {
> >>>>  	pinctrl-names = "default";
> >>>>  	pinctrl-0 = <&uart1_pins_a>;
> >>>> -	status = "disabled";
> >>>> +	status = "okay";
> >>>>  };
> >>>>  
> >>>>  &uart2 {
> >>>> +	pinctrl-names = "default";
> >>>> +	pinctrl-0 = <&uart2_pins_a>;
> >>>> +	status = "okay";
> >>>> +};
> >>>> +
> >>>> +&uart3 {
> >>>> +	pinctrl-names = "default";
> >>>> +	pinctrl-0 = <&uart3_pins_a>;
> >>>>  	status = "okay";
> >>>>  };
> >>>>  
> >>>
> >>> Why do we want to enable uart3 when there are only test points?
> >>> It is not very useful, or do I oversee something?
> >>>
> > 
> >> I have been listening to the sound from potential users of bpi-r2 to
> >> understand what assistance I have to provide to them. Something could
> >> be seen through [1] in the forum to know they had been trying hard to
> >> explore all available UARTs from the SoC in the last weeks. The patch
> >> should be really useful for these people and for the extra soldering
> >> it shouldn't become a problem for these makers.
> >>
> >> [1] http://forum.banana-pi.org/t/gpio-uart-not-the-debug-port/3748
> >>
> >> 	Sean 
> >>
> > 
> > Hi, Matthias
> > 
> > do you like it or quite want me to remove the uart3 node?
> > 
> > I can take it into account along with other pending dts changes in my
> > queue.
> > 
> 
> Sorry for the late answer.
> Do I understand correctly that uart3 is routed to TP47 and TP48, and these test
> points are accessible through the SATA connector? Doesn't they break SATA then?
> 

TP47 and TP48 are directly pins out from SoC, not through the SATA
connector.

> I think as they are only available through a non-documented test point, we
> shouldn't enable it.
> 

Okay, let's drop uart 3 setting here.

> Regards,
> Matthias