Messages in this thread | | | Date | Thu, 24 Jul 2014 17:06:43 +0200 | From | Jiří Prchal <> | Subject | Re: [PATCH] ARM: at91: at91sam9x5: sets NPCS0 (PA14) back to GPIO |
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Hi,
Dne 24.7.2014 v 16:26 Boris BREZILLON napsal(a): > Hello Jiří, > > First of all, please try to use git format-patch when submitting a > patch to any kernel mailing list. Sorry for that. > > On Thu, 24 Jul 2014 15:38:24 +0200 > Jiří Prchal <jiri.prchal@aksignal.cz> wrote: > >> After ROMBOOT tries boot from flash on SPI0 NPCS0, this NPCS0 (PA14) remains set to PERIPH_A. >> Because of that, this pin is unusable to something else. >> This patch sets it back to GPIO. > > The policy is to leave pins in an unknown state till some peripheral > need them. > > What are you trying to use this pin for ? For chip select, but #3. And when SPI communicate with cs0 (PA22), it goes down too (PA14), so 2 devices on bus were selected. > If you just want to use it as a chip select for an spi device, take a > look at [1]. At [1] it's OK until as cs0 is for example PA22 and cs1 is PA14. > > Here the gpio is requested by the spi core when defining the cs-gpios > property. The gpio controller then request the listed pins to the pin > controller (pinctrl driver). GPIO is not set in driver as GPIO, at least I didn't find it. > > You can explicitly define a new pinctrl state (by defining a new > pinctrl_spi0_cs0 subnode in your dts file) and reference it in the > spi0 node, though this is not mandatory. > > Best Regards, > > Boris > > [1]http://lxr.free-electrons.com/source/arch/arm/boot/dts/at91sam9x5ek.dtsi#L85 > -- 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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