linux-kernel - Re: [PATCH 14/14] staging: comedi: daqboard2000: prefer usleep

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Message-ID: <573C43B8.2090705@mev.co.uk>
Date:	Wed, 18 May 2016 11:28:08 +0100
From:	Ian Abbott <abbotti@....co.uk>
To:	Hartley Sweeten <HartleyS@...ionengravers.com>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 14/14] staging: comedi: daqboard2000: prefer
 usleep_range()

On 17/05/16 18:42, Hartley Sweeten wrote:
> On Tuesday, May 17, 2016 2:53 AM, Ian Abbott wrote:
>> The checkpatch.pl warns about two `udelay(x)` calls, one of 100
>> microseconds, and one of 10 microseconds.  The 100 microseconds one is
>> used when waiting for FPGA to become ready to accept firmware, and is
>> not that critical, so replace it with a call to `usleep_range(100,
>> 1000)`.  The 10 microseconds one is called as each 16-bit word of
>> firmware data is written.  A longer sleep would slow down firmware
>> loading, so leave it alone.
>
> The firmware blob in comedi-nonfree-firmware/daqboard2000 is
> 41236 bytes or 20618 words. With the 10 microsecond delay for
> each word to total delay time is only 0.0206 seconds. I don't think a
> small usleep_range() would slow down the firmware loading by much.
> How about usleep_range(10, 20)?
>
> Regards,
> Hartley

Okay.

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@....co.uk> )=-
-=(                          Web: http://www.mev.co.uk/  )=-