[PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[Dave Gerlach]

This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
bootloader configures gpio5_7 to control the DDR3 termination regulator,
the linked patch prevents that gpio bank from being reset and losing
the previously configured state, and this patch binds the gpio to a
regulator so the kernel is aware of the state of the gpio.

[1] https://www.mail-archive.com/linux-omap@vger.kernel.org/msg102941.html

Dave Gerlach (1):
  ARM: dts: am437x-gp-evm: Add vtt_fixed regulator

 arch/arm/boot/dts/am437x-gp-evm.dts | 11 +++++++++++
 1 file changed, 11 insertions(+)

-- 
1.9.0

[PATCH] ARM: dts: am437x-gp-evm: Add vtt_fixed regulator

[Dave Gerlach]

The VTT regulator for DDR3 termination on the am437x-gp-evm is
controlled by a gpio. It is configured by the bootloader so here we
define an always-on, fixed voltage regulator to hold the gpio.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
---
 arch/arm/boot/dts/am437x-gp-evm.dts | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm/boot/dts/am437x-gp-evm.dts b/arch/arm/boot/dts/am437x-gp-evm.dts
index a055f7f..e68d12c 100644
--- a/arch/arm/boot/dts/am437x-gp-evm.dts
+++ b/arch/arm/boot/dts/am437x-gp-evm.dts
@@ -27,6 +27,17 @@
 		enable-active-high;
 	};
 
+	vtt_fixed: fixedregulator-vtt {
+		compatible = "regulator-fixed";
+		regulator-name = "vtt_fixed";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-always-on;
+		regulator-boot-on;
+		enable-active-high;
+		gpio = <&gpio5 7 GPIO_ACTIVE_HIGH>;
+	};
+
 	backlight {
 		compatible = "pwm-backlight";
 		pwms = <&ecap0 0 50000 PWM_POLARITY_INVERTED>;
-- 
1.9.0

Re: [PATCH] ARM: dts: am437x-gp-evm: Add vtt_fixed regulator

[Nishanth Menon]

On 04/22/2014 01:52 PM, Dave Gerlach wrote:
> The VTT regulator for DDR3 termination on the am437x-gp-evm is
> controlled by a gpio. It is configured by the bootloader so here we
> define an always-on, fixed voltage regulator to hold the gpio.
> 
> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
> ---
>  arch/arm/boot/dts/am437x-gp-evm.dts | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/am437x-gp-evm.dts b/arch/arm/boot/dts/am437x-gp-evm.dts
> index a055f7f..e68d12c 100644
> --- a/arch/arm/boot/dts/am437x-gp-evm.dts
> +++ b/arch/arm/boot/dts/am437x-gp-evm.dts
> @@ -27,6 +27,17 @@
>  		enable-active-high;
>  	};
>  
> +	vtt_fixed: fixedregulator-vtt {

Would you like to consider any explicit pinctrl here?

> +		compatible = "regulator-fixed";
> +		regulator-name = "vtt_fixed";
> +		regulator-min-microvolt = <3300000>;
> +		regulator-max-microvolt = <3300000>;
> +		regulator-always-on;
> +		regulator-boot-on;
> +		enable-active-high;
> +		gpio = <&gpio5 7 GPIO_ACTIVE_HIGH>;
> +	};
> +
>  	backlight {
>  		compatible = "pwm-backlight";
>  		pwms = <&ecap0 0 50000 PWM_POLARITY_INVERTED>;
> 

Do we still need https://patchwork.kernel.org/patch/3871201/ (prevent
hwmod from resetting GPIO5) ?

-- 
Regards,
Nishanth Menon

Re: [PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[Tony Lindgren]

* Dave Gerlach <d-gerlach@ti.com> [140422 11:52]:
> This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
> bootloader configures gpio5_7 to control the DDR3 termination regulator,
> the linked patch prevents that gpio bank from being reset and losing
> the previously configured state, and this patch binds the gpio to a
> regulator so the kernel is aware of the state of the gpio.
> 
> [1] https://www.mail-archive.com/linux-omap@vger.kernel.org/msg102941.html

Setting up the GPIO regulator makes sense to me. But the hack in the
link above is potentially a nasty time bomb for anybody trying to
use GPIO bank 5 on that board.

What tests have been done that the GPIO bank behaves properly when
it's not reset?

Regards,

Tony

Re: [PATCH] ARM: dts: am437x-gp-evm: Add vtt_fixed regulator

[Dave Gerlach]

On 04/22/2014 01:58 PM, Nishanth Menon wrote:
> On 04/22/2014 01:52 PM, Dave Gerlach wrote:
>> The VTT regulator for DDR3 termination on the am437x-gp-evm is
>> controlled by a gpio. It is configured by the bootloader so here we
>> define an always-on, fixed voltage regulator to hold the gpio.
>>
>> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
>> ---
>>   arch/arm/boot/dts/am437x-gp-evm.dts | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/am437x-gp-evm.dts b/arch/arm/boot/dts/am437x-gp-evm.dts
>> index a055f7f..e68d12c 100644
>> --- a/arch/arm/boot/dts/am437x-gp-evm.dts
>> +++ b/arch/arm/boot/dts/am437x-gp-evm.dts
>> @@ -27,6 +27,17 @@
>>   		enable-active-high;
>>   	};
>>
>> +	vtt_fixed: fixedregulator-vtt {
>
> Would you like to consider any explicit pinctrl here?

Yes, it's a good idea for me to add that in for next version.

>
>> +		compatible = "regulator-fixed";
>> +		regulator-name = "vtt_fixed";
>> +		regulator-min-microvolt = <3300000>;
>> +		regulator-max-microvolt = <3300000>;
>> +		regulator-always-on;
>> +		regulator-boot-on;
>> +		enable-active-high;
>> +		gpio = <&gpio5 7 GPIO_ACTIVE_HIGH>;
>> +	};
>> +
>>   	backlight {
>>   		compatible = "pwm-backlight";
>>   		pwms = <&ecap0 0 50000 PWM_POLARITY_INVERTED>;
>>
>
> Do we still need https://patchwork.kernel.org/patch/3871201/ (prevent
> hwmod from resetting GPIO5) ?
>

Yes, without preventing the reset boot still hangs.

Re: [PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[Dave Gerlach]

On 04/22/2014 02:01 PM, Tony Lindgren wrote:
> * Dave Gerlach <d-gerlach@ti.com> [140422 11:52]:
>> This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
>> bootloader configures gpio5_7 to control the DDR3 termination regulator,
>> the linked patch prevents that gpio bank from being reset and losing
>> the previously configured state, and this patch binds the gpio to a
>> regulator so the kernel is aware of the state of the gpio.
>>
>> [1] https://www.mail-archive.com/linux-omap@vger.kernel.org/msg102941.html
>
> Setting up the GPIO regulator makes sense to me. But the hack in the
> link above is potentially a nasty time bomb for anybody trying to
> use GPIO bank 5 on that board.
>
> What tests have been done that the GPIO bank behaves properly when
> it's not reset?

We've been using this configuration on this board for a while without 
any apparent issues. Also, am335x-evmsk already uses the same idea for 
the VTT regulator on board from commit 
6046adb6ad701026c10adeac8d6a4138895f12e5 [ARM: dts: am335x-evmsk: Do not 
reset gpio0] and I am unaware of any issues with that either.

Regards,
Dave

>
> Regards,
>
> Tony
>

Re: [PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[Tony Lindgren]

* Dave Gerlach <d-gerlach@ti.com> [140422 12:53]:
> On 04/22/2014 02:01 PM, Tony Lindgren wrote:
> >* Dave Gerlach <d-gerlach@ti.com> [140422 11:52]:
> >>This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
> >>bootloader configures gpio5_7 to control the DDR3 termination regulator,
> >>the linked patch prevents that gpio bank from being reset and losing
> >>the previously configured state, and this patch binds the gpio to a
> >>regulator so the kernel is aware of the state of the gpio.
> >>
> >>[1] https://www.mail-archive.com/linux-omap@vger.kernel.org/msg102941.html
> >
> >Setting up the GPIO regulator makes sense to me. But the hack in the
> >link above is potentially a nasty time bomb for anybody trying to
> >use GPIO bank 5 on that board.
> >
> >What tests have been done that the GPIO bank behaves properly when
> >it's not reset?
> 
> We've been using this configuration on this board for a while without any
> apparent issues. Also, am335x-evmsk already uses the same idea for the VTT
> regulator on board from commit 6046adb6ad701026c10adeac8d6a4138895f12e5
> [ARM: dts: am335x-evmsk: Do not reset gpio0] and I am unaware of any issues
> with that either.

OK. Do you have other GPIOs in use as interrupts for devices in these
banks and do they work fine?

Also, can you please test to make sure this works with the most recent
Javier's GPIO patches that had the issue of not booting on am335x-evmsk?

Regards,

Tony

Re: [PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[Dave Gerlach]

On 04/23/2014 09:59 AM, Tony Lindgren wrote:
> * Dave Gerlach <d-gerlach@ti.com> [140422 12:53]:
>> On 04/22/2014 02:01 PM, Tony Lindgren wrote:
>>> * Dave Gerlach <d-gerlach@ti.com> [140422 11:52]:
>>>> This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
>>>> bootloader configures gpio5_7 to control the DDR3 termination regulator,
>>>> the linked patch prevents that gpio bank from being reset and losing
>>>> the previously configured state, and this patch binds the gpio to a
>>>> regulator so the kernel is aware of the state of the gpio.
>>>>
>>>> [1] https://www.mail-archive.com/linux-omap@vger.kernel.org/msg102941.html
>>>
>>> Setting up the GPIO regulator makes sense to me. But the hack in the
>>> link above is potentially a nasty time bomb for anybody trying to
>>> use GPIO bank 5 on that board.
>>>
>>> What tests have been done that the GPIO bank behaves properly when
>>> it's not reset?
>>
>> We've been using this configuration on this board for a while without any
>> apparent issues. Also, am335x-evmsk already uses the same idea for the VTT
>> regulator on board from commit 6046adb6ad701026c10adeac8d6a4138895f12e5
>> [ARM: dts: am335x-evmsk: Do not reset gpio0] and I am unaware of any issues
>> with that either.
>
> OK. Do you have other GPIOs in use as interrupts for devices in these
> banks and do they work fine?

I dont see any interrupts in use from gpio5 bank but as a quick test if 
I add ti,no-reset-on-init to gpio3 and gpio4 I see no issue with 
matrix-keypad operation which uses gpios from each of those banks.

>
> Also, can you please test to make sure this works with the most recent
> Javier's GPIO patches that had the issue of not booting on am335x-evmsk?
>

Yes, when using Javier's patches in addition to this patch [1], which 
was found to be necessary through this discussion [2], the AM437x GP EVM 
boots fine with linux-next with my regulator patch and gpio5 no reset 
patch applied.

Regards,
Dave

[1] https://patchwork.kernel.org/patch/4041881/
[2] http://marc.info/?t=139817273800014&r=1&w=2

> Regards,
>
> Tony
>

Re: [PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[Tony Lindgren]

* Dave Gerlach <d-gerlach@ti.com> [140423 10:25]:
> On 04/23/2014 09:59 AM, Tony Lindgren wrote:
> >* Dave Gerlach <d-gerlach@ti.com> [140422 12:53]:
> >>On 04/22/2014 02:01 PM, Tony Lindgren wrote:
> >>>* Dave Gerlach <d-gerlach@ti.com> [140422 11:52]:
> >>>>This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
> >>>>bootloader configures gpio5_7 to control the DDR3 termination regulator,
> >>>>the linked patch prevents that gpio bank from being reset and losing
> >>>>the previously configured state, and this patch binds the gpio to a
> >>>>regulator so the kernel is aware of the state of the gpio.
> >>>>
> >>>>[1] https://www.mail-archive.com/linux-omap@vger.kernel.org/msg102941.html
> >>>
> >>>Setting up the GPIO regulator makes sense to me. But the hack in the
> >>>link above is potentially a nasty time bomb for anybody trying to
> >>>use GPIO bank 5 on that board.
> >>>
> >>>What tests have been done that the GPIO bank behaves properly when
> >>>it's not reset?
> >>
> >>We've been using this configuration on this board for a while without any
> >>apparent issues. Also, am335x-evmsk already uses the same idea for the VTT
> >>regulator on board from commit 6046adb6ad701026c10adeac8d6a4138895f12e5
> >>[ARM: dts: am335x-evmsk: Do not reset gpio0] and I am unaware of any issues
> >>with that either.
> >
> >OK. Do you have other GPIOs in use as interrupts for devices in these
> >banks and do they work fine?
> 
> I dont see any interrupts in use from gpio5 bank but as a quick test if I
> add ti,no-reset-on-init to gpio3 and gpio4 I see no issue with matrix-keypad
> operation which uses gpios from each of those banks.

OK thanks for testing. I'll apply the ti,no-reset-on-init patch from [1]
above into omap-for-v3.15/fixes-v2.

The regulator patch can wait for v3.16, and should be also implemented
for the am335x-evmsk the same way, so maybe add that too to your patch?

> >Also, can you please test to make sure this works with the most recent
> >Javier's GPIO patches that had the issue of not booting on am335x-evmsk?
> >
> 
> Yes, when using Javier's patches in addition to this patch [1], which was
> found to be necessary through this discussion [2], the AM437x GP EVM boots
> fine with linux-next with my regulator patch and gpio5 no reset patch
> applied.

OK good to hear.

Tony
 
> [1] https://patchwork.kernel.org/patch/4041881/
> [2] http://marc.info/?t=139817273800014&r=1&w=2
> 
> >Regards,
> >
> >Tony
> >
> 

Re: [PATCH] ARM: dts: am437x-gp-evm: Boot fixes

[Dave Gerlach]

On 04/25/2014 11:41 AM, Tony Lindgren wrote:
> * Dave Gerlach <d-gerlach@ti.com> [140423 10:25]:
>> On 04/23/2014 09:59 AM, Tony Lindgren wrote:
>>> * Dave Gerlach <d-gerlach@ti.com> [140422 12:53]:
>>>> On 04/22/2014 02:01 PM, Tony Lindgren wrote:
>>>>> * Dave Gerlach <d-gerlach@ti.com> [140422 11:52]:
>>>>>> This patch, along with patch here [1], fixes boot for am437x-gp-evm. The
>>>>>> bootloader configures gpio5_7 to control the DDR3 termination regulator,
>>>>>> the linked patch prevents that gpio bank from being reset and losing
>>>>>> the previously configured state, and this patch binds the gpio to a
>>>>>> regulator so the kernel is aware of the state of the gpio.
>>>>>>
>>>>>> [1] https://www.mail-archive.com/linux-omap@vger.kernel.org/msg102941.html
>>>>>
>>>>> Setting up the GPIO regulator makes sense to me. But the hack in the
>>>>> link above is potentially a nasty time bomb for anybody trying to
>>>>> use GPIO bank 5 on that board.
>>>>>
>>>>> What tests have been done that the GPIO bank behaves properly when
>>>>> it's not reset?
>>>>
>>>> We've been using this configuration on this board for a while without any
>>>> apparent issues. Also, am335x-evmsk already uses the same idea for the VTT
>>>> regulator on board from commit 6046adb6ad701026c10adeac8d6a4138895f12e5
>>>> [ARM: dts: am335x-evmsk: Do not reset gpio0] and I am unaware of any issues
>>>> with that either.
>>>
>>> OK. Do you have other GPIOs in use as interrupts for devices in these
>>> banks and do they work fine?
>>
>> I dont see any interrupts in use from gpio5 bank but as a quick test if I
>> add ti,no-reset-on-init to gpio3 and gpio4 I see no issue with matrix-keypad
>> operation which uses gpios from each of those banks.
>
> OK thanks for testing. I'll apply the ti,no-reset-on-init patch from [1]
> above into omap-for-v3.15/fixes-v2.
>
> The regulator patch can wait for v3.16, and should be also implemented
> for the am335x-evmsk the same way, so maybe add that too to your patch?

Alright thanks, yes I can do that as well for v2.

Regards,
Dave

>
>>> Also, can you please test to make sure this works with the most recent
>>> Javier's GPIO patches that had the issue of not booting on am335x-evmsk?
>>>
>>
>> Yes, when using Javier's patches in addition to this patch [1], which was
>> found to be necessary through this discussion [2], the AM437x GP EVM boots
>> fine with linux-next with my regulator patch and gpio5 no reset patch
>> applied.
>
> OK good to hear.
>
> Tony
>
>> [1] https://patchwork.kernel.org/patch/4041881/
>> [2] http://marc.info/?t=139817273800014&r=1&w=2
>>
>>> Regards,
>>>
>>> Tony
>>>
>>