From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH] spi: Force the registration of the spidev devices Date: Wed, 13 May 2015 21:10:48 +0200 Message-ID: References: <1431462804-30467-1-git-send-email-maxime.ripard@free-electrons.com> <20150513112604.GI3066@sirena.org.uk> <20150513125102.GA2628@lukather> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Mark Brown , Greg Kroah-Hartman , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Hans de Goede , linux-spi , Martin Sperl , Michal Suchanek To: Maxime Ripard Return-path: In-Reply-To: <20150513125102.GA2628@lukather> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: On Wed, May 13, 2015 at 2:51 PM, Maxime Ripard wrote: >> > This also adds an i2cdev-like feeling, where you get all the >> > spidev devices all the time, without any modification. >> >> I2C is a bit safer here since it's a shared bus so you can't do >> anything to devices not connected to the bus by mistake. > > I'm not sure to understand what you mean here. How is SPI different > from that aspect? If you talk to a nonexistent i2c device, nothing happens, as it just sends a message with a nonexistent address on the shared bus. If you talk to a nonexistent spi device, hell may break loose if e.g. some "smart" hardware engineer used the "unused" CS as a pull-up for the _RESET line on an external device... It's a bit like banging random "unused" GPIOs. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- 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