[U-Boot] [PATCH 1/2] ARM: dts: zynq: Update dts for Z-turn board

[Michal Simek]

On 14.3.2018 23:40, Anton Gerasimov wrote:
> Hi Alexander,
> 
> 
>>>           device_type = "memory";
>>>           reg = <0x0 0x40000000>;
>>>       };
>>>         chosen {
>>> -        stdout-path = "serial0:115200n8";
>> Nack. By default graphical output is quite unusable on this board, so we
>> want to output to serial.
>>
>> If your Linux submitted device tree doesn't contain this part, please
>> fix it there.
>>
>>> +        bootargs = "console=ttyPS0,115200 earlyprintk
>>> root=/dev/mmcblk0p2 rootwait";
>> This is even worse. Please don't prepopulate any bootargs, otherwise
>> people may end up assuming that they're actually getting used.
> 
> The older one is much cleaner I agree, thank you. I'll just need to test
> with both u-boot and linux.
> 
>>>       };
>>>         gpio-leds {
>>>           compatible = "gpio-leds";
>>> -        led_r {
>>> -            label = "led_r";
>>> -            gpios = <&gpio0 0x72 0x1>;
>>> -            default-state = "on";
>>> -            linux,default-trigger = "heartbeat";
>>> -        };
>>> -
>>> -        led_g {
>>> -            label = "led_g";
>>> -            gpios = <&gpio0 0x73 0x1>;
>>> -            default-state = "on";
>>> -            linux,default-trigger = "heartbeat";
>>> -        };
>>> -
>>> -        led_b {
>>> -            label = "led_b";
>>> -            gpios = <&gpio0 0x74 0x1>;
>>> -            default-state = "on";
>>> -            linux,default-trigger = "heartbeat";
>>> -        };
>> Why remove them? They're hard wired on the board, no?
> No this RGB LED is connected to PL, that's for sure.
> 
>>>       ps-clk-frequency = <33333333>;
>>> -    fclk-enable = <0xf>;
>> Why?
> 
>> IIRC on my Z-Turn, I had to take a PL clock back into the PS as AXI
>> reference clock. See "Connect clocks" here:
>>
>>
>>
>>    https://wiki.hackerspace.pl/projects:zturn-hackers:helloworld
>>
>>
>>
>> So we need to have the PL clock enabled, no? Or is that only needed for
>> PL AXI peripherals?
>>
> 
> As far as I understand M_AXI_GPn connects AXI slaves implemented on PL
> to AXI and S_AXI_HPn provides access for AXI slaves in PS to PL slaves.
> So both involve PL and can be disconnected if PL is not clocked.

As you see that connection is done via PL. I am booting zynq boards
without fclk-enable and without PL and they are booting properly.
I have never had a time to investing what it is broken if you don't load
bitstream. Definitely feel free to test.
And as you see only one clk is used not all 4.


> 
>>>   };
>>>     &qspi {
>>> @@ -152,8 +114,8 @@
>>>           reg = <0x49>;
>>>       };
>>>   -    adxl345 at 53 {
>>> -        compatible = "adi,adxl34x", "adxl34x";
>>> +    accelerometer at 53 {
>>> +        compatible = "adi,adxl345", "adxl345";
>> You can't just remove compatibles. Device trees are supposed to be
>> compatible with whatever used them before someone thought they want to
>> prettify them, so in this case you'd have to add the concrete names in
>> the list before the abstract ones:
>>
>>    compatible = "adi,adxl345", "adxl345", "adi,adxl34x", "adxl34x";
> Yes sorry, I didn't realize that Linux kernel had both.

Ok. I think it will be good to sync these two dts with the kernel. It
means can you please send new updated version for linux kernel too?

Thanks,
Michal