Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753904Ab3FQSQB (ORCPT ); Mon, 17 Jun 2013 14:16:01 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:44597 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750970Ab3FQSQA (ORCPT ); Mon, 17 Jun 2013 14:16:00 -0400 Message-ID: <51BF525E.5080508@codeaurora.org> Date: Mon, 17 Jun 2013 11:15:58 -0700 From: Rohit Vaswani User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 MIME-Version: 1.0 To: Linus Walleij CC: Tony Lindgren , Ulf Hansson , Kevin Hilman , Stephen Warren , Linus Walleij , Stephen Warren , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH] pinctrl: document the pinctrl PM states References: <1370980749-15383-1-git-send-email-linus.walleij@stericsson.com> <51BA1FE7.4000900@wwwdotorg.org> <51BB3A2C.608@wwwdotorg.org> <20130617072021.GB4465@atomide.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2367 Lines: 62 On 6/17/2013 8:56 AM, Linus Walleij wrote: > On Mon, Jun 17, 2013 at 9:20 AM, Tony Lindgren wrote: > >> Maybe let's again try to first list all the known cases where we need to >> do remuxing, and the pins we need to remux? > In the pinctrl documentation this is known as "runtime pinmuxing". > This is not common, it is much more common to change > pin config, i.e. all other electrical properties of the pins, > at runtime. Especially when going to sleep or idle. MSM also does a significant amount of *remuxing* during suspend/resume. We have cases where a pin might be connected to a different device during normal operation with a different pull and higher drive strength and we will put it gpio mode, input for a low power configuration. Consolidating them into 1 operation would be preferred. >> Below are the pin remuxing cases I'm aware of: >> >> 1. Remux UART RX pin of a device for a wake-up event >> >> 2. Remux whatever device interrupt line to a GPIO input for wake-up >> >> 3. Remux audio jack between UART RX and TX to provide a debug console >> >> 4. Remux MMC CMD and DAT lines for sleep with pulls to avoid device >> from resetting with lines floating or to save power >> >> Please list any further use cases that I'm not familiar with. I'd like >> to hear how messed up this remuxing business can get :) > We have a debug port that can be muxed out on the keypad(!) > or the SD card, and some other variants... > > Stephen added the I2C block switch thing that switch one > and the same IP core between different sets of pins (IIRC). > > For runtime pin config I have many more examples, we > change a lot of those to so-called "GPIO mode" (basically > just turned into an input with wakeup, or pulled to ground) > at sleep. > > Yours, > Linus Walleij > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel Thanks, Rohit Vaswani -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation -- 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/