Re: [PATCH 2/6] arm64: Add DTS support for Spreadtrum's Shark64 SoC

[Lyra Zhang]

Hi, Arnd

This problem have been solved, and was submitted in v2.
Thanks for your answer to the question(which Orson asked for me) about
this on Freenode.

Best regards,
Lyra

2014-10-21 3:00 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>:
> On Wednesday 15 October 2014 11:17:07 Lyra Zhang wrote:
>> Hi, Arnd
>
> Hi Lyra,
>
> Sorry for the late reply, I've been away travelling and am just
> now catching up on email. Have you found a solution or do
> you still need help with this?
>
>         Arnd
>
>> 2014-09-29 21:47 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>:
>> > On Monday 29 September 2014 20:04:49 zhang.lyra@xxxxxxxxx wrote:
>> >> +
>> >> +/memreserve/ 0x80000000 0x00010000;
>> >
>> > Maybe add a comment explaining why it is reserved?
>> >
>> >> +     chosen {
>> >> +             bootargs = "earlycon=serial_sprd,0x70000000";
>> >> +      };
>> >
>> > Just remove this for now, the command line should really be set by the
>> > boot loader, not hardcoded in the dts file.
>> >
>> > IIRC, the earlycon=... syntax is not recommended on DT based systems,
>> > better use the "stdout-path" syntax instead.
>> >
>>
>> I have tried to use  "stdout-path" instead of "bootargs= "earlycon=
>> ..." like below :
>>
>> / {
>>      ...
>>
>>      chosen {
>>              stdout-path = "/serial@70000000";
>>       };
>>
>>      uart0: serial@70000000 {
>>              status="okay";
>>      };
>>       ...
>> };
>>
>> But then there is nothing output information on serial console.(I have
>> been testing in Fast Model)
>>
>>
>> I saw the below code in init/main.c
>>
>> /* Check for early params. */
>> static int __init do_early_param(char *param, char *val, const char *unused)
>> {
>> const struct obs_kernel_param *p;
>>
>> for (p = __setup_start; p < __setup_end; p++) {
>> if ((p->early && parameq(param, p->str)) ||
>>    (strcmp(param, "console") == 0 &&
>>     strcmp(p->str, "earlycon") == 0)
>> ) {
>> if (p->setup_func(val) != 0)
>> pr_warn("Malformed early option '%s'\n", param);
>> }
>> }
>> /* We accept everything at this stage. */
>> return 0;
>> }
>>
>> And I saw a patch from Grant Likely, he had a comment in it :
>> "If the devicetree specifies a serial port as a stdout device, then the
>> kernel can use it as the default console if nothing else was selected on
>> the command line. For any serial port that uses the uart_add_one_port()
>> feature, the uart_add_one_port() has all the information needed to
>> automatically enable the console device, which is what this patch does."
>>
>> So, I guess that the reason why I can't see any output information on
>> console after using "stdout-path" instead of "earlycon" is that I
>> haven't a driver of Spreadtrum's serial, and dose not use  the
>> uart_add_one_port() feature.
>>
>> I don't know is correct what I guess.
>>
>> Could you give me some suggestions to solve this problem?
>>
>
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