linux-kernel - Re: [PATCH v2] tty: serial: msm_serial.c: Cleaning up uninitialized variables

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Message-ID: <CAFo99gaqS747k9kVRh0uyt+TTmdi5RrXOxBb=pgEBca3eSpKTw@mail.gmail.com>
Date:	Wed, 9 Jul 2014 23:01:54 +0200
From:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	David Brown <davidb@...eaurora.org>,
	Daniel Walker <dwalker@...o99.com>,
	Bryan Huntsman <bryanh@...eaurora.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	linux-arm-msm@...r.kernel.org, linux-serial@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2] tty: serial: msm_serial.c: Cleaning up uninitialized variables

2014-07-09 20:02 GMT+02:00 Stephen Boyd <sboyd@...eaurora.org>:
> On 07/06/14 09:47, Rickard Strandqvist wrote:
>> Set reasonable initial value of some variables, in case
>> they do not get set to something otherwise.
>> And I've also added a plausibility control of the values.
>>
>> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
>> ---
>
> This patch doesn't look right...
>
>> @@ -930,17 +930,21 @@ static int __init msm_console_setup(struct console *co, char *options)
>>
>>       msm_init_clock(port);
>>
>> -     if (options)
>> +     if (options) {
>>               uart_parse_options(options, &baud, &parity, &bits, &flow);
>> +             if (baud < 300 || baud > 115200)
>> +                     baud = 115200;
>> +             if (NULL == strchr("noeNOE", parity))
>> +                     parity = 'n';
>> +             if (bits != 7)
>> +                     bits = 8;
>> +             if (flow != 'r')
>> +                     flow = 'n';
>> +     }
>>
>> -     bits = 8;
>> -     parity = 'n';
>> -     flow = 'n';
>>       msm_write(port, UART_MR2_BITS_PER_CHAR_8 | UART_MR2_STOP_BIT_LEN_ONE,
>>                 UART_MR2);    /* 8N1 */
>>
>
> because this code is overriding whatever is parsed from
> uart_parse_options() on purpose. The hardware is configured for 8 bits,
> no parity, no flow control with this msm_write() statement. Maybe we
> should extend the code to configure the parity and flow control bits
> instead.



Hi

Okay, well that explains the strange code.
Maybe there should be a comment about this?

You mean that UART_MR2_BITS_PER_CHAR_8 | UART_MR2_STOP_BIT_LEN_ONE is
set correctly for the msm_write function?
I can do that...

Regardless, the original error whas that baud could be used uninitialized.


Kind regards
Rickard Strandqvist
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