linux-kernel - Re: [PATCH] ARM: at91/dt: pullup dbgu rx instead of tx

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Message-ID: <5604154E.6050404@lysator.liu.se>
Date:	Thu, 24 Sep 2015 17:22:54 +0200
From:	Peter Rosin <peda@...ator.liu.se>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Peter Rosin <peda@...ntia.se>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] ARM: at91/dt: pullup dbgu rx instead of tx

On 2015-09-24 16:47, Alexandre Belloni wrote:
> Hi Peter,
> 
> Thanks for the patch but you actually got beaten by Sylvain:
> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-September/368426.html

Ok, great!

I just noticed that other ports have the same problem in sama5d3.dtsi. E.g.

	uart1 {
		pinctrl_uart1: uart1-0 {
			atmel,pins =
				<AT91_PIOA 30 AT91_PERIPH_B AT91_PINCTRL_NONE   /* conflicts with TWD0, ISI_VSYNC */
				 AT91_PIOA 31 AT91_PERIPH_B AT91_PINCTRL_PULL_UP>;      /* conflicts with TWCK0, ISI_HSYNC */
		};
	};

Given that the original bug I found spread all over the map, it seems
like someone was confused when the pull-ups were originally added.
Someone (else?) at Atmel needs to audit this so that pull-ups are
added on the rx-pins instead of the tx-pins.

Cheers,
Peter

> On 24/09/2015 at 16:44:15 +0200, Peter Rosin wrote :
>> From: Peter Rosin <peda@...ntia.se>
>>
>> It seems pointless to pullup the tx line, but there is value in pulling
>> up the rx line.
>>
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Peter Rosin <peda@...ntia.se>
>> ---
>>  arch/arm/boot/dts/sama5d3.dtsi |    4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/boot/dts/sama5d3.dtsi b/arch/arm/boot/dts/sama5d3.dtsi
>> index 9e2444b07bce..304a40c5552a 100644
>> --- a/arch/arm/boot/dts/sama5d3.dtsi
>> +++ b/arch/arm/boot/dts/sama5d3.dtsi
>> @@ -545,8 +545,8 @@
>>  				dbgu {
>>  					pinctrl_dbgu: dbgu-0 {
>>  						atmel,pins =
>> -							<AT91_PIOB 30 AT91_PERIPH_A AT91_PINCTRL_NONE	/* PB30 periph A */
>> -							 AT91_PIOB 31 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;	/* PB31 periph A with pullup */
>> +							<AT91_PIOB 30 AT91_PERIPH_A AT91_PINCTRL_PULL_UP	/* PB30 periph A with pullup */
>> +							 AT91_PIOB 31 AT91_PERIPH_A AT91_PINCTRL_NONE>;	/* PB31 periph A */
>>  					};
>>  				};
>>  
>> -- 
>> 1.7.10.4
>>
> 

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