[PATCH 1/2] spi: spidev: introduce SPI_IOC_WR_DEFAULT_MAX_SPEED_HZ command

From	Seraphime Kirkovski <kirkseraph@gmail.com>
Newsgroups	linux.kernel
Subject	[PATCH 1/2] spi: spidev: introduce SPI_IOC_WR_DEFAULT_MAX_SPEED_HZ command
Date	2017-05-15 10:30 +0200
Message-ID	<tHjy9-5Dw-7@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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christophe.blaess@gmail.com, fred@haapie.com
Bcc: Subject: Re: [PATCH 1/2] spi: spidev: introduce
 SPI_IOC_WR_DEFAULT_MAX_SPEED_HZ command
Reply-To: 
In-Reply-To: <20170514092716.kqx634djffgj32r6@sirena.org.uk>

On Sun, May 14, 2017 at 06:27:16PM +0900, Mark Brown wrote:
> On Tue, May 09, 2017 at 02:24:00PM +0200, Seraphime Kirkovski wrote:
> 
> > I think, this change is necessary, on the one hand, because there are still
> > a lot of longterm[2] supported kernels out there, whose users may be relying on
> > SPI_IOC_WR_MAX_SPEED being system-wide and, on the other hand, this
> > same command has been exhibiting a different behaviour for 3 years now,
> > so its users may break, if 9169051617df7 is reverted in one way or
> > another.
> 
> Do we have any evidence that such users exist?  

I can't guarantee for other such users, but this change did disturb our 
workflow. We were using this feature to prototype and test 
hardware/firmware at different speeds.

I was thinking this morning that maybe a sysfs interface will be better 
for setting global settings. Do you prefer ?

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[PATCH 1/2] spi: spidev: introduce SPI_IOC_WR_DEFAULT_MAX_SPEED_HZ  command Seraphime Kirkovski <kirkseraph@gmail.com> - 2017-05-15 10:30 +0200
  Re: [PATCH 1/2] spi: spidev: introduce  SPI_IOC_WR_DEFAULT_MAX_SPEED_HZ command Mark Brown <broonie@kernel.org> - 2017-05-17 11:10 +0200

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