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    SubjectRE: [PATCH] ARM: SAMSUNG: Save/restore GPIO drive strength across suspend/resume
    Thomas Abraham wrote at Monday, November 14, 2011 6:57 AM:
    > On 12 November 2011 16:30, Linus Walleij <linus.walleij@linaro.org> wrote:
    > > On Sat, Nov 12, 2011 at 6:01 AM, Inderpal Singh
    > > <inderpal.singh@linaro.org> wrote:
    > >
    > >> GPIO driver strength settings are not preserved across suspend/resume
    > >> for s5pc100, s5pv210 and Exynos platforms which has been the cause of
    > >> mmc/sd card read/write failures after resume. Fix this by saving and
    > >> restoring the GPIO driver strength register settings across suspend/resume.
    > >>
    > >> Signed-off-by: Inderpal Singh <inderpal.singh@linaro.org>
    > >
    > > On a related theme: I am thinking about how to support preserving
    > > drive strength (etc) across suspend/resume and deepsleep in the
    > > pincontrol subsystem.
    > >
    > > Currently I am playing with the idea to let pin groups have states,
    > > as the different configurations seem to be 90% or so about very
    > > specific sleep modes, so say:
    > >
    > > pinconf_set_group_state("mmcgroup", PINCONF_STATE_ACTIVE);
    > > pinconf_set_group_state("mmcgroup", PINCONF_STATE_SUSPENDED);
    > > pinconf_set_group_state("mmcgroup", PINCONF_STATE_SLEEP);
    >
    >
    > The API name suggests that power state is set based on a pin group.
    > For a driver, the following could be convenient as the driver transits
    > through various power management states.
    >
    > struct pinmux pmx;
    > pmx = pinmux_get(dev, "i2c0");
    >
    > [...]
    >
    > pinmux_set_state(pmx, PINCONF_STATE_SLEEP);
    > [...]
    > pinmux_set_state(pmx, PINCONF_STATE_ACTIVE);

    That seems a more consistent driver-oriented API, yes.

    I'd of course lean towards adding the pin config data into the mapping
    table, and using the existing feature struct pinmux_map name field to
    name those states, and allowing dynamic transitioning between states,
    rather than adding a complete new API and namespace for these states.

    --
    nvpublic



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