Messages in this thread | | | Date | Mon, 17 Jun 2013 11:15:58 -0700 | From | Rohit Vaswani <> | Subject | Re: [PATCH] pinctrl: document the pinctrl PM states |
| |
On 6/17/2013 8:56 AM, Linus Walleij wrote: > On Mon, Jun 17, 2013 at 9:20 AM, Tony Lindgren <tony@atomide.com> 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
| |