[RFC 2/2] DTS: davinci: da850evm: Enable LCD and Backlight

[Adam Ford]

On Mon, Sep 11, 2017 at 5:02 AM, Sekhar Nori <nsekhar at ti.com> wrote:
> On Saturday 09 September 2017 10:28 AM, Adam Ford wrote:
>> When using the board files the LCD works, but not with the DT.
>> This adds enables the original da850-evm to work with the same
>> LCD in device tree mode.
>>
>> RFC:  Currently, I cannot get the backlight to do anything other
>> than 100%. I don't get the userspace files to write the brightness.
>> Any suggestions on what I am dowing wrong?
>
> Not sure what went wrong for you here, but applying your patches and
> building the new kernel & modules did create the
> /sys/class/backlight/backlight/brightness needed.
>
> That said, the brightness changes did not seem take effect. I did not
> debug it further.
>

It looks like there is an issue with the PWM.  The pin is able to be
muxed between EPWM0_TZ or ECAP2_PWM2.
I am trying to use ecap2, but when looking at the pin on the scope
it's not toggling.  Is that the correct PWM to use?

Do you know if ecap2 is setup to clock correctly on L138 using DT?
Looking at this patch, do you see anything that stands out

Thanks for any suggestions you might have.  I know I let this go stale
for a while, but I'm still trying to modernize the DT whenever
possible.

adam
> Do you have the pwm_bl and backlight modules loaded?
>
>> RFC:  The board-file version enables the LCD, but the only way
>> I can enable the LCD is the disable the VPIF display.  Should
>> I use a new name for the this DTS file to maintain compatibility,
>> or is there a better way to enable the LCD without losing VPIF
>
> For pinmux clashes of this sort, we need to keep one of the nodes
> disabled (status = "disabled"). In future, a device-tree overlay may be
> used to enable the node. For now, user has to hand-edit the device-tree
> file to disable LCD node and enable VPIF display.
>
> In case of VPIF, it looks like the pins should be part of the display
> port node (port at 1) so only the display port can be kept disabled. I have
> not tried to see if thats possible.
>
>> Signed-off-by: Adam Ford <aford173 at gmail.com>
>
> Can you follow subject line prefix format of existing patches on this
> file. See:
>
> $ git log --oneline arch/arm/boot/dts/da850-evm.dts
>
>>
>> diff --git a/arch/arm/boot/dts/da850-evm.dts b/arch/arm/boot/dts/da850-evm.dts
>> index 67e72bc..10df630 100644
>> --- a/arch/arm/boot/dts/da850-evm.dts
>> +++ b/arch/arm/boot/dts/da850-evm.dts
>> @@ -10,6 +10,7 @@
>>  /dts-v1/;
>>  #include "da850.dtsi"
>>  #include <dt-bindings/gpio/gpio.h>
>> +#include <dt-bindings/pwm/pwm.h>
>>
>>  / {
>>       compatible = "ti,da850-evm", "ti,da850";
>> @@ -30,6 +31,7 @@
>>                                       0x04 0x00011000 0x000ff000
>>                               >;
>>                       };
>> +
>
> Please drop this stray change for next time.
>
> Thanks,
> Sekhar