Re: [PATCHv2] wlcore: spi: add wl18xx support

From	Mark Brown <broonie@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCHv2] wlcore: spi: add wl18xx support
Date	2016-04-19 19:10 +0200
Message-ID	<rpHjZ-1Nv-25@gated-at.bofh.it> (permalink)
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On Mon, Apr 18, 2016 at 05:55:51AM +0000, Reizer, Eyal wrote:

> > I would suggest fixing this using a new API function from the SPI core, if we
> > don't already have a generic way to do it.

> Originally this is what I have done until I was pointed to the generic cs-gpio mechanism 
> in the SPI core. 
> It is a generic mechanism already in the SPI core driver.
> See: Documentation/devicetree/bindings/spi/spi-bus.txt

> It is also part of the generic spi.h (include/Linux/spi/spi.h), already part of 
> " struct spi_device" So it seemed redundant adding another mechanism for 
> implementing the same.

No!  This is a *terrible* and broken idea.  Client drivers should *not*
be peering inside controller implementations like this, and they should
especially not be trying to change the chip select without the core
knowing about it.  This is at best going to be fragile, at worst it will
actively break some systems.  Whatever you are trying to do needs to go
through the SPI core with some degree of abstraction, the core needs to
know what's going on and the driver needs to support systems that don't
or can't mux the chip select out as a GPIO.

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Re: [PATCHv2] wlcore: spi: add wl18xx support Arnd Bergmann <arnd@arndb.de> - 2016-04-18 00:30 +0200
  RE: [PATCHv2] wlcore: spi: add wl18xx support "Reizer, Eyal" <eyalr@ti.com> - 2016-04-18 08:00 +0200
    Re: [PATCHv2] wlcore: spi: add wl18xx support Arnd Bergmann <arnd@arndb.de> - 2016-04-18 17:00 +0200
      RE: [PATCHv2] wlcore: spi: add wl18xx support "Reizer, Eyal" <eyalr@ti.com> - 2016-04-19 11:10 +0200
        Re: [PATCHv2] wlcore: spi: add wl18xx support Arnd Bergmann <arnd@arndb.de> - 2016-04-19 16:30 +0200
          RE: [PATCHv2] wlcore: spi: add wl18xx support "Reizer, Eyal" <eyalr@ti.com> - 2016-04-19 16:40 +0200
        Re: [PATCHv2] wlcore: spi: add wl18xx support Mark Brown <broonie@kernel.org> - 2016-04-19 19:20 +0200
          Re: [PATCHv2] wlcore: spi: add wl18xx support Mark Brown <broonie@kernel.org> - 2016-04-19 19:30 +0200
            Re: [PATCHv2] wlcore: spi: add wl18xx support Mark Brown <broonie@kernel.org> - 2016-04-19 20:00 +0200
              Re: [PATCHv2] wlcore: spi: add wl18xx support Mark Brown <broonie@kernel.org> - 2016-04-19 20:50 +0200
                RE: [PATCHv2] wlcore: spi: add wl18xx support "Reizer, Eyal" <eyalr@ti.com> - 2016-04-21 13:10 +0200
                Re: [PATCHv2] wlcore: spi: add wl18xx support Mark Brown <broonie@kernel.org> - 2016-04-21 13:20 +0200
    Re: [PATCHv2] wlcore: spi: add wl18xx support Mark Brown <broonie@kernel.org> - 2016-04-19 19:10 +0200

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