From mboxrd@z Thu Jan 1 00:00:00 1970 From: Baruch Siach Subject: Re: [PATCH 0/4] spi: dw: fixes, and manages resources migration Date: Wed, 1 Jan 2014 07:01:30 +0200 Message-ID: <20140101050130.GG4263@tarshish> References: <20131226115507.GI8064@book.gsilab.sittig.org> <20131226121224.GA11794@sapphire.tkos.co.il> <20131226154250.GO8064@book.gsilab.sittig.org> <20131226203423.GC3873@tarshish> <20131231123425.GP8064@book.gsilab.sittig.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Mark Brown , linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Feng Tang , Jean-Hugues Deschenes To: Gerhard Sittig Return-path: Content-Disposition: inline In-Reply-To: <20131231123425.GP8064-kDjWylLy9wD0K7fsECOQyeGNnDKD8DIp@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Hi Gerhard, On Tue, Dec 31, 2013 at 01:34:25PM +0100, Gerhard Sittig wrote: > On Thu, Dec 26, 2013 at 22:34 +0200, Baruch Siach wrote: > > That's what I meant. The "dummy-cs" should be an internal > > chip-select that does not control any slave signal. [ ... ] > > Ah, nevermind then, I simply misunderstood. :) Thinking about it again I think that "dummy-cs" is not a good name. Maybe "disconnected-cs" would be better. This is the actual hardware level description of the chip-select, rather than software level use as dummy value. [...] > So the introduction of another dummy-cs property might be > appropriate given the observed behaviour of the hardware. > Alternatively one might just pick an arbitrary internal CS number > at runtime (probably the highest internal number, i.e. the last > one), which should not be a problem as long as this behaviour is > documented -- GPIOs then can get used for this CS number and all > numbers above, so no functionality is missing. Mind that this > workaround then is a feature of the Linux driver, and not the DT > binding. Choosing an arbitrary chip-select number is dangerous. You might damage the hardware by choosing wrong. I don't think that relying on documentation (where?) is reasonable in this case. baruch -- http://baruch.siach.name/blog/ ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - baruch-NswTu9S1W3P6gbPvEgmw2w@public.gmane.org - tel: +972.2.679.5364, http://www.tkos.co.il - -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html