Messages in this thread | | | Date | Thu, 31 Jul 2014 17:59:06 +0200 | From | Alexandre Belloni <> | Subject | Re: [PATCH] ARM: at91: spi: request all csgpio in spi probe |
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On 29/07/2014 at 10:00:17 +0200, Boris Brezillon wrote : > Hi Alexandre, > > > While this solves the particular issue Jiří is seeing, this will not > > solve the case where PA14 (CS0) is not used by the spi driver at all. It > > will remained muxed as CS0 and toggle when the spi master needs to > > access CS0 until another driver muxes it to something else. I still > > believe we should explicitly ask pinctrl to mux them as gpios. > > > > Do we really care about this case ? > After all, if a given pin needs a specific muxing during kernel boot > (i.e. a pin connected to a gpio-led that needs to stay in its previous > state or a pin connected to the reset line of a device that needs to > stay up and running during kernel boot) the bootloader/bootstrap should > have muxed this pin appropriately before booting the kernel. >
Yeah, you are right.
> What do you mean by "we should explicitly ask pinctrl to mux them as > gpios" ? > Do you mean configuring all the pins as GPIOs when the pin controller is > probed, or just adding a new pinctrl state configuring the pin as an > output GPIO and reference it in the pinctrl-0 property of the spi > controller. > > If the former, you'll break devices that needs their pins to stay in > the state they were during the bootloader/boostrap phase. > The latter won't work if the pin you request as GPIO is later requested > by another device (which, if I'm correct, is exactly the case you're > trying to solve). >
Again you are right, let's not care about that use case. I still feel that the pinctrl-0 property has to be filled correctly.
-- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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