Re: [RFC PATCH 0/3] UART slave device bus

From	Linus Walleij <linus.walleij@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH 0/3] UART slave device bus
Date	2016-08-24 14:30 +0200
Message-ID	<s9FtD-2aP-11@gated-at.bofh.it> (permalink)
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On Mon, Aug 22, 2016 at 5:45 PM, One Thousand Gnomes
<gnomes@lxorguk.ukuu.org.uk> wrote:

> and if I look at the usermode crapfest on a lot of Android systems it
> looks similar but with the notion of things like being able to describe
>
> -       Use GPIO mode sleeping and assume first char is X to save power

It's really nasty hardware design, or a software hack to solve
a hardware problem: what should have been done is
of course create a UART with an asynchronous low-power mode
that can recieve a character and wake up the system at any time,
handing over the wakeup character(s) to the driver. That is
obviously the usecase they were designing for.

But yeah, I guess we have to contain hacks like that.

> -       Power up, wait n ms, write, read, wait n ms, power down (which
>         has to be driven at the ldisc/user level as only the ldisc
>         understands transactions, or via ioctls (right now Android user
>         space tends to do hardcoded writes to /sys.. gpio to drive power

This kind of abominational abuse of the GPIO sysfs ABI is
partly why I've obsoleted it. The right abstraction is the
fixed regulator with a GPIO line obviously, then some
sequencing along the lines of what you can find in
drivers/mmc/core/pwrseq*

Unfortunately that sysfs ABI crept in during a window of time
when GPIO was unmaintained and I am trying my best to
contain and improve the situation.

Yours,
Linus Walleij

Thread

[RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-18 03:20 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 12:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 12:40 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:00 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-18 16:00 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-18 15:20 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-19 03:50 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:10 +0200
  Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 12:40 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 12:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:00 +0200
        Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-18 16:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:10 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-08-18 13:30 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 13:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 14:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 13:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:20 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:50 +0200
            Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 14:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 15:10 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:00 +0200
      Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 13:10 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-18 13:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-18 14:10 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-18 13:10 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Linus Walleij <linus.walleij@linaro.org> - 2016-08-18 15:20 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-19 03:50 +0200
  Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-18 16:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 03:10 +0200
    Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 03:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-19 04:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:40 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 17:40 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 03:30 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-19 03:40 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 07:30 +0200
        Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 09:40 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Oleksij Rempel <linux@rempel-privat.de> - 2016-08-19 10:00 +0200
            Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 20:00 +0200
              Re: [RFC PATCH 0/3] UART slave device bus Oleksij Rempel <linux@rempel-privat.de> - 2016-08-19 22:30 +0200
              Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-20 15:40 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-21 10:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-22 22:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-22 23:30 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 23:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 00:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 01:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 01:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-23 09:30 +0200
          Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-19 19:50 +0200
              Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-20 15:30 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-21 10:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-21 19:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-08-21 20:30 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 11:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 11:40 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 13:10 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-19 16:50 +0200
  Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 14:40 +0200
    Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-22 15:50 +0200
      Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 17:30 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 17:30 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Arnd Bergmann <arnd@arndb.de> - 2016-08-22 18:00 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-22 18:50 +0200
          Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 19:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 19:40 +0200
              Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 23:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 23:40 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Pavel Machek <pavel@ucw.cz> - 2016-08-23 00:10 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 01:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 02:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 02:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 03:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-24 16:00 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-24 16:40 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-23 13:50 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 01:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-22 19:40 +0200
              Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-22 22:10 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-23 00:10 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 00:20 +0200
        Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-22 19:20 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Marcel Holtmann <marcel@holtmann.org> - 2016-08-22 23:10 +0200
            Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 00:10 +0200
              Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 01:20 +0200
                Re: [RFC PATCH 0/3] UART slave device bus Sebastian Reichel <sre@kernel.org> - 2016-08-23 01:50 +0200
            Re: [RFC PATCH 0/3] UART slave device bus One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-23 00:20 +0200
          Re: [RFC PATCH 0/3] UART slave device bus Linus Walleij <linus.walleij@linaro.org> - 2016-08-24 14:30 +0200
        Re: [RFC PATCH 0/3] UART slave device bus Rob Herring <robh@kernel.org> - 2016-08-23 23:20 +0200

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