linux-kernel - Re: [PATCH] use callbacks to access UART_DLL/UART

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Date:	Thu, 17 Dec 2015 18:09:07 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Sebastian Frias <sf84@...oste.net>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Magnus Damm <damm@...nsource.se>, linux-serial@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>, Mason <slash.tmp@...e.fr>
Subject: Re: [PATCH] use callbacks to access UART_DLL/UART_DLM

Sebastian Frias <sf84@...oste.net> writes:

>>>        old_lcr = serial_in(p, UART_LCR);
>>> -    serial_out(p, UART_LCR, UART_LCR_CONF_MODE_A);
>>> -
>>> -    old_dll = serial_in(p, UART_DLL);
>>> -    old_dlm = serial_in(p, UART_DLM);
>>>
>>> -    serial_out(p, UART_DLL, 0);
>>> -    serial_out(p, UART_DLM, 0);
>>> +    serial_out(p, UART_LCR, UART_LCR_CONF_MODE_A);
>>>
>>> -    id = serial_in(p, UART_DLL) | serial_in(p, UART_DLM) << 8;
>>> +    old_dl = serial_dl_read(p);
>>> +    serial_dl_write(p, 0);
>>> +    id = serial_dl_read(p);
>>> +    serial_dl_write(p, old_dl);
>>>
>>> -    serial_out(p, UART_DLL, old_dll);
>>> -    serial_out(p, UART_DLM, old_dlm);
>>>        serial_out(p, UART_LCR, old_lcr);
>>>
>>>        return id;
>>> --
>>
>> If you left the blank lines alone, the patch would end up much easier to
>> understand.  In this diff, some of the lines listed as added or removed
>> have actually not changed, and that's not immediately obvious.
>>
>
> The old code had some blank lines, which I suppose were there for clarity.
> I attempted to follow the same idea.
> But I don't mind changing the code as you wish.

It could well be that your patch results in a clearer final version, but
the diff is harder to parse when unchanged lines have moved around.

-- 
Måns Rullgård
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