From mboxrd@z Thu Jan 1 00:00:00 1970 From: swarren@wwwdotorg.org (Stephen Warren) Date: Mon, 11 Feb 2013 14:13:36 -0700 Subject: [PATCH] pinctrl/pinconfig: add debug interface In-Reply-To: <20130211210041.GW4801@atomide.com> References: <1360527070-18430-1-git-send-email-linus.walleij@stericsson.com> <51195A63.7080706@wwwdotorg.org> <20130211210041.GW4801@atomide.com> Message-ID: <51195F00.4020309@wwwdotorg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/11/2013 02:00 PM, Tony Lindgren wrote: > * Stephen Warren [130211 12:57]: >> On 02/10/2013 01:11 PM, Linus Walleij wrote: >>> From: Laurent Meunier >>> >>> This update adds a debugfs interface to modify a pin configuration >>> for a given state in the pinctrl map. This allows to modify the >>> configuration for a non-active state, typically sleep state. >>> This configuration is not applied right away, but only when the state >>> will be entered. >>> >>> This solution is mandated for us by HW validation: in order >>> to test and verify several pin configurations during sleep without >>> recompiling the software. >> >> I never understood why HW engineers can't just recompile the kernel. >> Besides, it's just a device tree change these days - no recompile even >> required, right? > > Typically when bringing up a new board you do not have the driver > specific mux settings verified. For developers, it's easiest to tweak > the muxing during runtime do the drivers as a loadable module, then > export the verified mux configuration into a .dts file. Well HW engineers typically just write to the HW registers directly rather than screwing around with the Linux pinctrl tables and unloading/reloading drivers.