[PATCH v5 11/11] riscv: Add FPIOA and GPIO support for Kendryte K210

[Sean Anderson]

On 8/18/20 11:48 PM, Rick Chen wrote:
> Hi Tom
> 
>> This patch adds the necessary configs and docs for FPIOA and GPIO support
>> on the K210.
>>
>> The board does not boot unless CONSOLE_LOGLEVEL is set to a non-default
>> value . It also boots when the tree is dirty (and CONSOLE_LOGLEVEL is not
>> changed). It also boots when changes are made to the device tree and then
>> committed. I don't know why this happens. These breakages only occur after
>> bf2fb81ad3.
>>
>> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
>> ---
>>
>> Changes in v5:
>> - Increase CONSOLE_LOGLEVEL to 5 as a hack to get the board booting again
>> - Patch 05/12 "gpio: sifive: Use generic reg read function" has been superseded
>>   by commit 2548493ab4.
> 
> Would you like to pick up this series, [PATCH v5 00/11] riscv: Add
> FPIOA and GPIO support for Kendryte K210 ?
> Or maybe it is better to figure out what is wrong here and find the
> root cause why it need to Increase CONSOLE_LOGLEVEL to 5 as a hack ?

As an additional note, *CONFIG_LOGLEVEL (whoops) can also be decreased
for the same effect. In addition, there are several other ways I found
to "fix" this bug (as noted in the commit message). If you would like to
test this out, I have two trees [1, 2] where this series (actually a slightly
earlier version of this series) is applied just before and just after
bf2fb81ad3. The original patch is located at [3].

--Sean

[1] https://github.com/Forty-Bot/u-boot/tree/maix_gpio_good
[2] https://github.com/Forty-Bot/u-boot/tree/maix_gpio_bad
[3] https://patchwork.ozlabs.org/project/uboot/patch/20200724111225.12513-15-ovidiu.panait@windriver.com/