2010/8/19 Mike Frysinger <[email protected]>:
> On Thursday, August 19, 2010 12:15:45 Frans Meulenbroeks wrote:
>> Hm. I thought about open/close too. Triggered by your comments I wrote
>> a small test app.
>> If I use fopen/fclose and in a while loop do:
>>            fputc('0', fp);
>>            fputc('1', fp);
>> I get a wave with period  1.96 uS.
>> If I move to open/close with a while loop like:
>>            write(fd, "0", 1);
>>            write(fd, "1", 1);
>> the period reduces to 1.53 uS.
>> Same hw (1.2 ghz ppc)
>
> but what is the difference in your jtag transfers ?

I've no idea, I just crafted a small test program that toggles the gpio flag.
I didn't get to converting the whole gpio module

>> BTW: i tried open with and without O_DIRECT but that did not seem to
>> make any difference.
>
> O_DIRECT is meaningless to pseudo file systems like sysfs

Yeah, figured that, but to be sure I tried it anyway.

Frans

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