From mboxrd@z Thu Jan  1 00:00:00 1970
From: Renato Andreola <renato.andreola@imagos.it>
Date: Fri, 07 Aug 2009 14:14:06 +0200
Subject: [U-Boot] PATCH mtd CFI flash: timeout calculation underflow if
 imprecise 1kHz timer: fix
In-Reply-To: <20090807091647.3F231832E416@gemini.denx.de>
References: <4A7AD624.9030902@imagos.it>
	<20090806202615.GH13346@game.jcrosoft.org>
	<20090806205329.8A31C832E416@gemini.denx.de>
	<4A7BE28A.8080701@imagos.it>
	<20090807091647.3F231832E416@gemini.denx.de>
Message-ID: <4A7C1A8E.2080208@imagos.it>
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To: u-boot@lists.denx.de

Ok, for the change.
What is the preferred way to proceed? have I got to resubmit a patch for 
the change with the DIV_ROUND_UP macro?

Best regards,
Renato Andreola

Wolfgang Denk wrote:
> Dear Renato Andreola,
>
> In message <4A7BE28A.8080701@imagos.it> you wrote:
>   
>> I'd like to clarify what is the problem with the timeout and the Intel 
>> flash (even if the following comments can be obvious or already well 
>> known) and to ask you an opinion on a small code change.
>>     
>
> Thanks.
>
> ...
>   
>> I think that an expression like this
>>
>> #if CONFIG_SYS_HZ != 1000
>> if ((ulong)CONFIG_SYS_HZ > 10000)
>>     tout *= ((ulong)CONFIG_SYS_HZ)/1000;  /* for a big HZ, avoid 
>> overflow */
>> else
>>     tout = (tout * (ulong)CONFIG_SYS_HZ + 500) / 1000;
>> #endif
>>
>> could be better because
>> - it forces the data type of the system dependent CONFIG_SYS_HZ value to 
>> ulong (no float!)
>> - it rounds tout to 0.5 timer tick and leaves tout unchanged if 
>> CONFIG_SYS_HZ == 1000
>>
>> What do you think about?
>>     
>
> I'd prefer "tout = DIV_ROUND_UP(tout*CONFIG_SYS_HZ, 1000);"
>
>
> Best regards,
>
> Wolfgang Denk
>
>