linux-kernel - Re: [RFC][PATCH v2 2/3] spi_bitbang : get nsecs delay from cs during transfer

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Message-ID: <AANLkTimdw5crEJTdnObURp_kxqjwFas2RuDMewd=CqEG@mail.gmail.com>
Date:	Tue, 14 Dec 2010 11:58:39 -0500
From:	Ben Gardiner <bengardiner@...ometrics.ca>
To:	Wolfram Sang <w.sang@...gutronix.de>
Cc:	spi-devel-general@...ts.sourceforge.net,
	Grant Likely <grant.likely@...retlab.ca>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	linux-kernel@...r.kernel.org, Michael Buesch <mb@...sch.de>
Subject: Re: [RFC][PATCH v2 2/3] spi_bitbang : get nsecs delay from cs during transfer

On Fri, Dec 10, 2010 at 6:46 AM, Wolfram Sang <w.sang@...gutronix.de> wrote:
> Hi,
>
> thanks for the submission. It has some issues, though:

Hi Wolfram,

Thanks for the comments, I appreciate your interest in the RFC.

> On Thu, Dec 09, 2010 at 03:34:55PM -0500, Ben Gardiner wrote:
>
>> +             nsecs =
>> +#if defined(CONFIG_SLOWER_SPI_GPIO)
>> +                             !cs->nsecs ? cs->nsecs : 100;
>> +#else
>> +             100;
>> +#endif
>
> This coding style is very hard to read and gains nothing for it. Also,
> slower_spi should rather be a per-device than a config option.

Yes, now that you mention it the implementation looks very clunky.

I think it is starting to sink-in that a 'slower' spi gpio _driver_ is
needed. I can think of a couple different ways to make the CS-to-data
delay assigned to 'nsecs' a per-device feature:
1) a flag or 2) a function pointer in struct spi_bitbang. Were you
thinking of something else entirely?

Best Regards,
Ben Gardiner

---
Nanometrics Inc.
http://www.nanometrics.ca
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