[U-Boot] [PATCH] serial: ns16550: fix different reg size access

Wolfgang Denk
2011-04-01T19:04:41Z

Dear Prafulla Wadaskar,

In message <F766E4F80769BD478052FB6533FA745D19F9A29D36@SC-VEXCH4.marvell.com> you wrote:
>
> 1. ns16550 is standard IP used across several SoC and has driver in place.
> 2. Your specific implementation of the same IP on your specific SoC need
> bit9 or x register to be set to 0 to work this IP correctly on your h/w.
> 3. but doing in ns16550 driver may brake other implementations.

Right.

> (correct me if I am wrong)
>
> So what I suggest here-
> 1. do not disturb/touch nx16550 driver at all.
> 2. write a small init code in cpu.c (specific to this SoC/arch) to reset this bit only.

Sorry, but I dislike this approach. I think it would be better to
provide a proper driver infrastructure for this type of UART, as it
might be used in other appliances, and it is a good idea to keep all
related code parts together in one driver file.

Here is what I suggested (I think I repeat it the 3rd time now):

| 2) If you have additional, non-standard bits in your device, you must
| initialize these separately. Eventually you provide a custom
| driver which just calls the standard NS16550 driver functions,
| except where you have additional need to manipulate the extra,
| non-standard bits of your device.

Thanks.

Wolfgang Denk

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