2019-12-03 14:24:13

by Ingo van Lil

Subject: [PATCH] ARM: dts: at91: Reenable UART TX pull-ups

Pull-ups for SAM9 UART/USART TX lines were disabled in a previous
commit. However, several chips in the SAM9 family require pull-ups to
prevent the TX lines from falling (and causing an endless break
condition) when the transceiver is disabled.

From the SAM9G20 datasheet, 32.5.1: "To prevent the TXD line from
falling when the USART is disabled, the use of an internal pull up
is mandatory.". This commit reenables the pull-ups for all chips having
that sentence in their datasheets.

Fixes: 5e04822f7db5 ("ARM: dts: at91: fixes uart pinctrl, set pullup on rx, clear pullup on tx")
Signed-off-by: Ingo van Lil <[email protected]>
Cc: Peter Rosin <[email protected]>
---
arch/arm/boot/dts/at91sam9260.dtsi | 12 ++++++------
arch/arm/boot/dts/at91sam9261.dtsi | 6 +++---
arch/arm/boot/dts/at91sam9263.dtsi | 6 +++---
arch/arm/boot/dts/at91sam9g45.dtsi | 8 ++++----
arch/arm/boot/dts/at91sam9rl.dtsi | 8 ++++----
5 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/arm/boot/dts/at91sam9260.dtsi b/arch/arm/boot/dts/at91sam9260.dtsi
index dee9c0c8a096..16c6fd3c4246 100644
--- a/arch/arm/boot/dts/at91sam9260.dtsi
+++ b/arch/arm/boot/dts/at91sam9260.dtsi
@@ -187,7 +187,7 @@
usart0 {
pinctrl_usart0: usart0-0 {
atmel,pins =
- <AT91_PIOB 4 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 4 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 5 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -221,7 +221,7 @@
usart1 {
pinctrl_usart1: usart1-0 {
atmel,pins =
- <AT91_PIOB 6 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 6 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 7 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -239,7 +239,7 @@
usart2 {
pinctrl_usart2: usart2-0 {
atmel,pins =
- <AT91_PIOB 8 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 8 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 9 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -257,7 +257,7 @@
usart3 {
pinctrl_usart3: usart3-0 {
atmel,pins =
- <AT91_PIOB 10 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 10 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 11 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -275,7 +275,7 @@
uart0 {
pinctrl_uart0: uart0-0 {
atmel,pins =
- <AT91_PIOA 31 AT91_PERIPH_B AT91_PINCTRL_NONE
+ <AT91_PIOA 31 AT91_PERIPH_B AT91_PINCTRL_PULL_UP
AT91_PIOA 30 AT91_PERIPH_B AT91_PINCTRL_PULL_UP>;
};
};
@@ -283,7 +283,7 @@
uart1 {
pinctrl_uart1: uart1-0 {
atmel,pins =
- <AT91_PIOB 12 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 12 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 13 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};
};
diff --git a/arch/arm/boot/dts/at91sam9261.dtsi b/arch/arm/boot/dts/at91sam9261.dtsi
index dba025a98527..5ed3d745ac86 100644
--- a/arch/arm/boot/dts/at91sam9261.dtsi
+++ b/arch/arm/boot/dts/at91sam9261.dtsi
@@ -329,7 +329,7 @@
usart0 {
pinctrl_usart0: usart0-0 {
atmel,pins =
- <AT91_PIOC 8 AT91_PERIPH_A AT91_PINCTRL_NONE>,
+ <AT91_PIOC 8 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>,
<AT91_PIOC 9 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -347,7 +347,7 @@
usart1 {
pinctrl_usart1: usart1-0 {
atmel,pins =
- <AT91_PIOC 12 AT91_PERIPH_A AT91_PINCTRL_NONE>,
+ <AT91_PIOC 12 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>,
<AT91_PIOC 13 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -365,7 +365,7 @@
usart2 {
pinctrl_usart2: usart2-0 {
atmel,pins =
- <AT91_PIOC 14 AT91_PERIPH_A AT91_PINCTRL_NONE>,
+ <AT91_PIOC 14 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>,
<AT91_PIOC 15 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

diff --git a/arch/arm/boot/dts/at91sam9263.dtsi b/arch/arm/boot/dts/at91sam9263.dtsi
index 99678abdda93..5c990cfae254 100644
--- a/arch/arm/boot/dts/at91sam9263.dtsi
+++ b/arch/arm/boot/dts/at91sam9263.dtsi
@@ -183,7 +183,7 @@
usart0 {
pinctrl_usart0: usart0-0 {
atmel,pins =
- <AT91_PIOA 26 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOA 26 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOA 27 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -201,7 +201,7 @@
usart1 {
pinctrl_usart1: usart1-0 {
atmel,pins =
- <AT91_PIOD 0 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOD 0 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOD 1 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -219,7 +219,7 @@
usart2 {
pinctrl_usart2: usart2-0 {
atmel,pins =
- <AT91_PIOD 2 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOD 2 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOD 3 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

diff --git a/arch/arm/boot/dts/at91sam9g45.dtsi b/arch/arm/boot/dts/at91sam9g45.dtsi
index 691c95ea6175..fd179097a4bf 100644
--- a/arch/arm/boot/dts/at91sam9g45.dtsi
+++ b/arch/arm/boot/dts/at91sam9g45.dtsi
@@ -556,7 +556,7 @@
usart0 {
pinctrl_usart0: usart0-0 {
atmel,pins =
- <AT91_PIOB 19 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 19 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 18 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -574,7 +574,7 @@
usart1 {
pinctrl_usart1: usart1-0 {
atmel,pins =
- <AT91_PIOB 4 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 4 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 5 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -592,7 +592,7 @@
usart2 {
pinctrl_usart2: usart2-0 {
atmel,pins =
- <AT91_PIOB 6 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 6 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 7 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -610,7 +610,7 @@
usart3 {
pinctrl_usart3: usart3-0 {
atmel,pins =
- <AT91_PIOB 8 AT91_PERIPH_A AT91_PINCTRL_NONE
+ <AT91_PIOB 8 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
AT91_PIOB 9 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

diff --git a/arch/arm/boot/dts/at91sam9rl.dtsi b/arch/arm/boot/dts/at91sam9rl.dtsi
index 8643b7151565..ea024e4b6e09 100644
--- a/arch/arm/boot/dts/at91sam9rl.dtsi
+++ b/arch/arm/boot/dts/at91sam9rl.dtsi
@@ -682,7 +682,7 @@
usart0 {
pinctrl_usart0: usart0-0 {
atmel,pins =
- <AT91_PIOA 6 AT91_PERIPH_A AT91_PINCTRL_NONE>,
+ <AT91_PIOA 6 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>,
<AT91_PIOA 7 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -721,7 +721,7 @@
usart1 {
pinctrl_usart1: usart1-0 {
atmel,pins =
- <AT91_PIOA 11 AT91_PERIPH_A AT91_PINCTRL_NONE>,
+ <AT91_PIOA 11 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>,
<AT91_PIOA 12 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -744,7 +744,7 @@
usart2 {
pinctrl_usart2: usart2-0 {
atmel,pins =
- <AT91_PIOA 13 AT91_PERIPH_A AT91_PINCTRL_NONE>,
+ <AT91_PIOA 13 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>,
<AT91_PIOA 14 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

@@ -767,7 +767,7 @@
usart3 {
pinctrl_usart3: usart3-0 {
atmel,pins =
- <AT91_PIOB 0 AT91_PERIPH_A AT91_PINCTRL_NONE>,
+ <AT91_PIOB 0 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>,
<AT91_PIOB 1 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
};

--
2.21.0

2019-12-10 10:58:37

by Alexandre Belloni

Subject: Re: [PATCH] ARM: dts: at91: Reenable UART TX pull-ups

On 03/12/2019 15:21:47+0100, Ingo van Lil wrote:
> Pull-ups for SAM9 UART/USART TX lines were disabled in a previous
> commit. However, several chips in the SAM9 family require pull-ups to
> prevent the TX lines from falling (and causing an endless break
> condition) when the transceiver is disabled.
>
> From the SAM9G20 datasheet, 32.5.1: "To prevent the TXD line from
> falling when the USART is disabled, the use of an internal pull up
> is mandatory.". This commit reenables the pull-ups for all chips having
> that sentence in their datasheets.
>
> Fixes: 5e04822f7db5 ("ARM: dts: at91: fixes uart pinctrl, set pullup on rx, clear pullup on tx")
> Signed-off-by: Ingo van Lil <[email protected]>
> Cc: Peter Rosin <[email protected]>
> ---
> arch/arm/boot/dts/at91sam9260.dtsi | 12 ++++++------
> arch/arm/boot/dts/at91sam9261.dtsi | 6 +++---
> arch/arm/boot/dts/at91sam9263.dtsi | 6 +++---
> arch/arm/boot/dts/at91sam9g45.dtsi | 8 ++++----
> arch/arm/boot/dts/at91sam9rl.dtsi | 8 ++++----
> 5 files changed, 20 insertions(+), 20 deletions(-)
>
Applied, thanks.

--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com