[PATCH RFC 0/4] ARM: bcm2835: assign pins to sdhci pinctrl

[PATCH RFC 0/4] ARM: bcm2835: assign pins to sdhci pinctrl

[Stefan Wahren]

This patch series fixes the pinctrl of the sdhci pins for all
Raspberry Pis.

The pin configuration based on the proprietary DTS [1].

[1] - https://www.raspberrypi.org/documentation/configuration/images/dt-blob.dts

Stefan Wahren (4):
  ARM: bcm2835: remove sdhci pins from GPIO pinctrl
  ARM: bcm2835: rename sdhci pin group
  ARM: bcm2835: specify card detect pin for RPi B
  ARM: bcm2835: assign pins to sdhci pinctrl

 arch/arm/boot/dts/bcm2835-rpi-a-plus.dts |    6 +++++-
 arch/arm/boot/dts/bcm2835-rpi-b-plus.dts |    6 +++++-
 arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts |    6 +++++-
 arch/arm/boot/dts/bcm2835-rpi-b.dts      |   11 ++++++++++-
 arch/arm/boot/dts/bcm2835-rpi.dtsi       |    2 +-
 5 files changed, 26 insertions(+), 5 deletions(-)

-- 
1.7.9.5

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[PATCH RFC 1/4] ARM: bcm2835: remove sdhci pins from GPIO pinctrl

[Stefan Wahren]

Currently the pins alt3 (sdhci) are assigned to GPIO pinctrl.
This is bad because a user could export it to sysfs and break
sdhci. In order to avoid that remove those pins from GPIO pintrl.

Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
---
 arch/arm/boot/dts/bcm2835-rpi-a-plus.dts |    2 +-
 arch/arm/boot/dts/bcm2835-rpi-b-plus.dts |    2 +-
 arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts |    2 +-
 arch/arm/boot/dts/bcm2835-rpi-b.dts      |    2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
index b2bff43..50be11d 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
@@ -20,7 +20,7 @@
 };
 
 &gpio {
-	pinctrl-0 = <&gpioout &alt0 &i2s_alt0 &alt3>;
+	pinctrl-0 = <&gpioout &alt0 &i2s_alt0>;
 
 	/* I2S interface */
 	i2s_alt0: i2s_alt0 {
diff --git a/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts b/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts
index 668442b..43dd5ef 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts
@@ -20,7 +20,7 @@
 };
 
 &gpio {
-	pinctrl-0 = <&gpioout &alt0 &i2s_alt0 &alt3>;
+	pinctrl-0 = <&gpioout &alt0 &i2s_alt0>;
 
 	/* I2S interface */
 	i2s_alt0: i2s_alt0 {
diff --git a/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts b/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts
index eab8b591..e5a65a8 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts
@@ -13,7 +13,7 @@
 };
 
 &gpio {
-	pinctrl-0 = <&gpioout &alt0 &i2s_alt2 &alt3>;
+	pinctrl-0 = <&gpioout &alt0 &i2s_alt2>;
 
 	/* I2S interface */
 	i2s_alt2: i2s_alt2 {
diff --git a/arch/arm/boot/dts/bcm2835-rpi-b.dts b/arch/arm/boot/dts/bcm2835-rpi-b.dts
index ff6b2d1..e6cd93b 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-b.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-b.dts
@@ -13,5 +13,5 @@
 };
 
 &gpio {
-	pinctrl-0 = <&gpioout &alt0 &alt3>;
+	pinctrl-0 = <&gpioout &alt0>;
 };
-- 
1.7.9.5

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Re: [PATCH RFC 1/4] ARM: bcm2835: remove sdhci pins from GPIO pinctrl

[Stephen Warren]

On 11/19/2015 09:06 AM, Stefan Wahren wrote:
> Currently the pins alt3 (sdhci) are assigned to GPIO pinctrl.
> This is bad because a user could export it to sysfs and break
> sdhci. In order to avoid that remove those pins from GPIO pintrl.

> diff --git a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts

>  &gpio {
> -	pinctrl-0 = <&gpioout &alt0 &i2s_alt0 &alt3>;
> +	pinctrl-0 = <&gpioout &alt0 &i2s_alt0>;

This doesn't make sense. The current DT content is configuring those
pins as SDHCI, not as GPIO. Admitedly this is redundant since the
firmware and/or bootloader already did this in order to boot the system,
but irrespective, the current DT causes no issues. Removing the pinctrl
setting should not influence whether the pins can be exported via GPIO
sysfs either.
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Re: [PATCH RFC 1/4] ARM: bcm2835: remove sdhci pins from GPIO pinctrl

[Stefan Wahren]

> Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> hat am 2. Dezember 2015 um 04:40
> geschrieben:
>
>
> On 11/19/2015 09:06 AM, Stefan Wahren wrote:
> > Currently the pins alt3 (sdhci) are assigned to GPIO pinctrl.
> > This is bad because a user could export it to sysfs and break
> > sdhci. In order to avoid that remove those pins from GPIO pintrl.
>
> > diff --git a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
> > b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
>
> > &gpio {
> > - pinctrl-0 = <&gpioout &alt0 &i2s_alt0 &alt3>;
> > + pinctrl-0 = <&gpioout &alt0 &i2s_alt0>;
>
> This doesn't make sense. The current DT content is configuring those
> pins as SDHCI, not as GPIO. Admitedly this is redundant since the
> firmware and/or bootloader already did this in order to boot the system,
> but irrespective, the current DT causes no issues. Removing the pinctrl
> setting should not influence whether the pins can be exported via GPIO
> sysfs either.

You are right. 

Is it generally possible to avoid the GPIO sysfs export for SDHCI pins? 
Is it an issue of pinctrl-bcm2835?
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Re: [PATCH RFC 1/4] ARM: bcm2835: remove sdhci pins from GPIO pinctrl

[Stephen Warren]

On 12/05/2015 02:12 AM, Stefan Wahren wrote:
> 
>> Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> hat am 2. Dezember 2015 um 04:40
>> geschrieben:
>>
>>
>> On 11/19/2015 09:06 AM, Stefan Wahren wrote:
>>> Currently the pins alt3 (sdhci) are assigned to GPIO pinctrl.
>>> This is bad because a user could export it to sysfs and break
>>> sdhci. In order to avoid that remove those pins from GPIO pintrl.
>>
>>> diff --git a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
>>> b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
>>
>>> &gpio {
>>> - pinctrl-0 = <&gpioout &alt0 &i2s_alt0 &alt3>;
>>> + pinctrl-0 = <&gpioout &alt0 &i2s_alt0>;
>>
>> This doesn't make sense. The current DT content is configuring those
>> pins as SDHCI, not as GPIO. Admitedly this is redundant since the
>> firmware and/or bootloader already did this in order to boot the system,
>> but irrespective, the current DT causes no issues. Removing the pinctrl
>> setting should not influence whether the pins can be exported via GPIO
>> sysfs either.
> 
> You are right. 
> 
> Is it generally possible to avoid the GPIO sysfs export for SDHCI pins? 
> Is it an issue of pinctrl-bcm2835?

I believe this same issue exists on all platforms where GPIO pins can be
mux'd onto the same pins as other functions.

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[PATCH RFC 2/4] ARM: bcm2835: rename sdhci pin group

[Stefan Wahren]

The node name of the sdhci pin group doesn't explain it's
real function. So rename it.

Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
---
 arch/arm/boot/dts/bcm2835-rpi.dtsi |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi b/arch/arm/boot/dts/bcm2835-rpi.dtsi
index 3572f03..c5dc57f 100644
--- a/arch/arm/boot/dts/bcm2835-rpi.dtsi
+++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi
@@ -36,7 +36,7 @@
 		brcm,function = <BCM2835_FSEL_ALT0>;
 	};
 
-	alt3: alt3 {
+	sdhci_alt3: sdhci_alt3 {
 		brcm,pins = <48 49 50 51 52 53>;
 		brcm,function = <BCM2835_FSEL_ALT3>;
 	};
-- 
1.7.9.5

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Re: [PATCH RFC 2/4] ARM: bcm2835: rename sdhci pin group

[Stephen Warren]

On 11/19/2015 09:06 AM, Stefan Wahren wrote:
> The node name of the sdhci pin group doesn't explain it's
> real function. So rename it.

The real function of this node is not to configure SDHCI pins, but to
set pins to alt3, as the current name states. Admittedly it's possible
that currently the only pins that need to be set to ALT3 are SDHCI
related, but that's incidental.
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Re: [PATCH RFC 2/4] ARM: bcm2835: rename sdhci pin group

[Stefan Wahren]

> Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> hat am 2. Dezember 2015 um 04:42
> geschrieben:
>
>
> On 11/19/2015 09:06 AM, Stefan Wahren wrote:
> > The node name of the sdhci pin group doesn't explain it's
> > real function. So rename it.
>
> The real function of this node is not to configure SDHCI pins, but to
> set pins to alt3, as the current name states. Admittedly it's possible
> that currently the only pins that need to be set to ALT3 are SDHCI
> related, but that's incidental.

Yes, i understand the original intension to assign every pin to the available
mux functions ( gpio_in, gpio_out, alt* ).

But 3f37169fb3 ("ARM: bcm2835: dt: Add Raspberry Pi Model B rev2") introduce a
better self-describing pin group naming for I2S. So my idea was to adapt it
according to sdhci first and go on.

So here is a possible vision for bcm2835-rpi.dtsi

&gpio {
	pinctrl-names = "default";

	act_gpio: gpio {
		brcm,pins = <6>;
		brcm,function = <BCM2835_FSEL_GPIO_OUT>;
	};

	i2c0_alt0: i2c {
		brcm,pins = <0 1>;
		brcm,function = <BCM2835_FSEL_ALT0>;
	};

	i2c1_alt0: i2c {
		brcm,pins = <2 3>;
		brcm,function = <BCM2835_FSEL_ALT0>;
	};
	
	gpclk_alt0: gpclk {
		brcm,pins = <4 5>;
		brcm,function = <BCM2835_FSEL_ALT0>;
	};
	
	spi0_alt0: spi {
		brcm,pins = <7 8 9 10 11>;
		brcm,function = <BCM2835_FSEL_ALT0>;
	};
	
	uart0_alt0: spi {
		brcm,pins = <14 15>;
		brcm,function = <BCM2835_FSEL_ALT0>;
	};
	
	pwm0_alt0: pwm {
		brcm,pins = <40>;
		brcm,function = <BCM2835_FSEL_ALT0>;
	};
	
	pwm1_alt0: pwm {
		brcm,pins = <45>;
		brcm,function = <BCM2835_FSEL_ALT0>;
	};

	sdhci_alt3: sdhci_alt3 {
		brcm,pins = <48 49 50 51 52 53>;
		brcm,function = <BCM2835_FSEL_ALT3>;
	};
};

Best regards
Stefan
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Re: [PATCH RFC 2/4] ARM: bcm2835: rename sdhci pin group

[Stephen Warren]

On 12/05/2015 02:43 AM, Stefan Wahren wrote:
> 
>> Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> hat am 2. Dezember 2015 um 04:42
>> geschrieben:
>>
>>
>> On 11/19/2015 09:06 AM, Stefan Wahren wrote:
>>> The node name of the sdhci pin group doesn't explain it's
>>> real function. So rename it.
>>
>> The real function of this node is not to configure SDHCI pins, but to
>> set pins to alt3, as the current name states. Admittedly it's possible
>> that currently the only pins that need to be set to ALT3 are SDHCI
>> related, but that's incidental.
> 
> Yes, i understand the original intension to assign every pin to the available
> mux functions ( gpio_in, gpio_out, alt* ).
> 
> But 3f37169fb3 ("ARM: bcm2835: dt: Add Raspberry Pi Model B rev2") introduce a

FYI I don't have that yet and git fetch is being very slow right now:-(

> better self-describing pin group naming for I2S. So my idea was to adapt it
> according to sdhci first and go on.

OK. I'd suggest explaining that directly in the commit description then.
The commit description above has a quite different semantic meaning.

> So here is a possible vision for bcm2835-rpi.dtsi
> 
> &gpio {
> 	pinctrl-names = "default";
> 
> 	act_gpio: gpio {
> 		brcm,pins = <6>;
> 		brcm,function = <BCM2835_FSEL_GPIO_OUT>;
> 	};
> 
> 	i2c0_alt0: i2c {
> 		brcm,pins = <0 1>;
> 		brcm,function = <BCM2835_FSEL_ALT0>;
> 	};
> 
> 	i2c1_alt0: i2c {
> 		brcm,pins = <2 3>;
> 		brcm,function = <BCM2835_FSEL_ALT0>;
> 	};
...

OK, I guess that can work; I imagine it would make DT overlays easier by
making the pinctrl setup more fine-grained.
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[PATCH RFC 3/4] ARM: bcm2835: specify card detect pin for RPi B

[Stefan Wahren]

Only the Raspberry Pi B has a card detect pin. Specify it
on board level because it's not free to use.

Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
---
 arch/arm/boot/dts/bcm2835-rpi-b.dts |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2835-rpi-b.dts b/arch/arm/boot/dts/bcm2835-rpi-b.dts
index e6cd93b..1be2220 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-b.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-b.dts
@@ -14,4 +14,9 @@
 
 &gpio {
 	pinctrl-0 = <&gpioout &alt0>;
+
+	sdhci_cd: sdhci_cd {
+		brcm,pins = <47>;
+		brcm,function = <BCM2835_FSEL_GPIO_IN>;
+	};
 };
-- 
1.7.9.5

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Re: [PATCH RFC 3/4] ARM: bcm2835: specify card detect pin for RPi B

[Stephen Warren]

On 11/19/2015 09:06 AM, Stefan Wahren wrote:
> Only the Raspberry Pi B has a card detect pin. Specify it
> on board level because it's not free to use.

This seems fine, but it should have no effect in practice; when the SD
controller driver gpio_get()s the GPIO, the same setting will be
programmed into HW. There's a requirement to use the pinctrl bindings to
configure pins to non-GPIO mux settings, but no actual requirement to do
so for GPIOs.

However, the new node sdhci_cd should be added to some pinctrl-0
property or it won't be used.
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Re: [PATCH RFC 3/4] ARM: bcm2835: specify card detect pin for RPi B

[Stefan Wahren]

Am 02.12.2015 um 04:44 schrieb Stephen Warren:
> On 11/19/2015 09:06 AM, Stefan Wahren wrote:
>> Only the Raspberry Pi B has a card detect pin. Specify it
>> on board level because it's not free to use.
> This seems fine, but it should have no effect in practice; when the SD
> controller driver gpio_get()s the GPIO, the same setting will be
> programmed into HW. There's a requirement to use the pinctrl bindings to
> configure pins to non-GPIO mux settings, but no actual requirement to do
> so for GPIOs.
>
> However, the new node sdhci_cd should be added to some pinctrl-0
> property or it won't be used.

This is done in Patch 4
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[PATCH RFC 4/4] ARM: bcm2835: assign pins to sdhci pinctrl

[Stefan Wahren]

Finally this patch assign all relevant pins to the sdhci pinctrl.

Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
---
 arch/arm/boot/dts/bcm2835-rpi-a-plus.dts |    4 ++++
 arch/arm/boot/dts/bcm2835-rpi-b-plus.dts |    4 ++++
 arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts |    4 ++++
 arch/arm/boot/dts/bcm2835-rpi-b.dts      |    4 ++++
 4 files changed, 16 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
index 50be11d..4d562d9 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
@@ -28,3 +28,7 @@
 		brcm,function = <BCM2835_FSEL_ALT0>;
 	};
 };
+
+&sdhci {
+	pinctrl-0 = <&sdhci_alt3>;
+};
diff --git a/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts b/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts
index 43dd5ef..27a533a 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-b-plus.dts
@@ -28,3 +28,7 @@
 		brcm,function = <BCM2835_FSEL_ALT0>;
 	};
 };
+
+&sdhci {
+	pinctrl-0 = <&sdhci_alt3>;
+};
diff --git a/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts b/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts
index e5a65a8..dcc1627 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts
@@ -21,3 +21,7 @@
 		brcm,function = <BCM2835_FSEL_ALT2>;
 	};
 };
+
+&sdhci {
+	pinctrl-0 = <&sdhci_alt3>;
+};
diff --git a/arch/arm/boot/dts/bcm2835-rpi-b.dts b/arch/arm/boot/dts/bcm2835-rpi-b.dts
index 1be2220..bdb9308 100644
--- a/arch/arm/boot/dts/bcm2835-rpi-b.dts
+++ b/arch/arm/boot/dts/bcm2835-rpi-b.dts
@@ -20,3 +20,7 @@
 		brcm,function = <BCM2835_FSEL_GPIO_IN>;
 	};
 };
+
+&sdhci {
+	pinctrl-0 = <&sdhci_alt3 &sdhci_cd>;
+};
-- 
1.7.9.5

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Re: [PATCH RFC 4/4] ARM: bcm2835: assign pins to sdhci pinctrl

[Eric Anholt]

[-- Attachment #1: Type: text/plain, Size: 1177 bytes --]

Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org> writes:

> Finally this patch assign all relevant pins to the sdhci pinctrl.
>
> Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
> ---
>  arch/arm/boot/dts/bcm2835-rpi-a-plus.dts |    4 ++++
>  arch/arm/boot/dts/bcm2835-rpi-b-plus.dts |    4 ++++
>  arch/arm/boot/dts/bcm2835-rpi-b-rev2.dts |    4 ++++
>  arch/arm/boot/dts/bcm2835-rpi-b.dts      |    4 ++++
>  4 files changed, 16 insertions(+)
>
> diff --git a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
> index 50be11d..4d562d9 100644
> --- a/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
> +++ b/arch/arm/boot/dts/bcm2835-rpi-a-plus.dts
> @@ -28,3 +28,7 @@
>  		brcm,function = <BCM2835_FSEL_ALT0>;
>  	};
>  };
> +
> +&sdhci {
> +	pinctrl-0 = <&sdhci_alt3>;
> +};

[...]

What effect does this have?  Does this change any pinmuxing at boot?  If
so, is it just resetting things from what the firmware has set to what
we expect it to be?  Does it enable card detection on the Pi B?

As far as the whole series, I really like the improved description in
patch 2, and patch 3 seems like a good idea, too.

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