Re: [Xen-devel] [RFC PATCH 1/2] xen/arm: Add Amlogic S905 SoC early printk support

[Amit Tomer <amittomer25@xxxxxxxxx>]

Hello,

> I would prefer if no new alias are added. The same could be achieved with
> CONFIG_EARLY_PRINTK=meson,0xc81004c0.
>
> This could be documented on the wiki.

Ok.

> I would prefer if we stick with the spec name. So UART_TX_REG should be
> renamed UART_WFIFO_REG.

Yeah right, got your point.
>
> Also, it might be worth considering to prefix them with AML_ so it is easy
> to find them on lookup.

Initially used AML_ as prefix but then I just wanted to be consistent it with
other uart drivers in XEN.

> Looking at the earlyconsole implementation in Linux, it seems that TX needs
> to be enabled first (see meson_uart_enable_tx_engine).
>
> Is it now done in the firmware?

Yes, this has been done in u-boot.
shouldn't we trust it?


>> + */
>> +.macro early_uart_ready xb c
>> +1:
>> +        ldrh   w\c, [\xb, #UART_STATUS_REG] /* status register */
>> +        tst    w\c, #(1 << 21)              /* Check TXFIFO FULL bit */
>
>
> Please define 1 << 21 rather than hardcoding it.

Ok.


Thanks
-Amit

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