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    SubjectRe: [PATCH v3 1/2] mfd: da9062: enable being a system-power-controller
    On Tue, 28 Jun 2022, Helmut Grohne wrote:

    > The DA9062 can be the device used to power the CPU. In that case, it can
    > be used to power off the system. In the CONTROL_A register, the M_*_EN
    > bits must be zero for the corresponding *_EN bits to have an effect. We
    > zero them all to turn off the system.
    >
    > Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>
    > ---
    > drivers/mfd/da9062-core.c | 34 ++++++++++++++++++++++++++++++++++
    > 1 file changed, 34 insertions(+)
    >
    > Compared to v2, this addresses the following concerns raised by Lee Jones:
    > * Drop unnecessary comment.
    > * Restructure da9062_power_off to avoid unnecessary assignments.
    > * Make power off failure message user friendly while still including
    > the error code for diagnostics.
    >
    > Lee Jones also questioned the utility of warning about pm_power_off already
    > being assigned:
    >
    > > Do we really mind/care?
    > >
    > > Is there anything we can do about it?
    > >
    > > Thus, do we really need to warn() about it?
    >
    > I do think this is useful, because it only happens when two nodes decalare
    > being a system-power-controller. It is a misconfiguration of your device tree
    > that is being warned here. Other drivers (e.g. rn5t618.c, act8865-regulator.c,
    > rtc-jz4740.c, and bcm2835_wdt.c) issue a similar warning.
    >
    > I note that Adam Thomson reviewed v2. Thank you. I did not include the
    > Reviewed-by, because noticeable code changed compared to what was reviewed.
    >
    > As pointed out by Adam Thomson, this version still uses regmap (and possibly
    > mutexes) in pm_power_off (with irqs disabled). This is a fundamental problem
    > shared with many other pm_power_off hooks.
    >
    > I've now included Rob Herring's Acked-by on the second patch as the rebase was
    > trivial.
    >
    > Helmut
    > diff --git a/drivers/mfd/da9062-core.c b/drivers/mfd/da9062-core.c
    > index 2774b2cbaea6..0083a2756f28 100644
    > --- a/drivers/mfd/da9062-core.c
    > +++ b/drivers/mfd/da9062-core.c
    > @@ -620,6 +620,26 @@ static const struct of_device_id da9062_dt_ids[] = {
    > };
    > MODULE_DEVICE_TABLE(of, da9062_dt_ids);
    >
    > +static struct i2c_client *da9062_i2c_client;
    > +
    > +static void da9062_power_off(void)
    > +{
    > + int ret;
    > +
    > + ret = regmap_update_bits(
    > + ((struct
    > da9062*)i2c_get_clientdata(da9062_i2c_client))->regmap,

    This is ugly. Please pull this out of the function args and separate
    the whole thing. No func()->attribute craziness please.

    > + DA9062AA_CONTROL_A,
    > + DA9062AA_SYSTEM_EN_MASK | DA9062AA_POWER_EN_MASK |
    > + DA9062AA_POWER1_EN_MASK | DA9062AA_M_SYSTEM_EN_MASK |
    > + DA9062AA_M_POWER_EN_MASK | DA9062AA_M_POWER1_EN_MASK,
    > + 0
    > + );
    > +
    > + if (ret < 0)
    > + dev_err(&da9062_i2c_client->dev,
    > + "failed to power the system off (err=%d)\n", ret);

    Either start with a uppercase char, or don't. Please be consistent.

    > +}
    > +
    > static int da9062_i2c_probe(struct i2c_client *i2c,
    > const struct i2c_device_id *id)
    > {
    > @@ -720,6 +740,15 @@ static int da9062_i2c_probe(struct i2c_client *i2c,
    > return ret;
    > }
    >
    > + if (of_device_is_system_power_controller(i2c->dev.of_node)) {
    > + if (!pm_power_off) {
    > + da9062_i2c_client = i2c;
    > + pm_power_off = da9062_power_off;
    > + } else {
    > + dev_warn(&i2c->dev, "Poweroff callback already assigned\n");
    > + }
    > + }
    > +
    > return ret;
    > }
    >
    > @@ -727,6 +756,11 @@ static int da9062_i2c_remove(struct i2c_client *i2c)
    > {
    > struct da9062 *chip = i2c_get_clientdata(i2c);
    >
    > + if (pm_power_off == da9062_power_off)
    > + pm_power_off = NULL;
    > + if (da9062_i2c_client)
    > + da9062_i2c_client = NULL;
    > +
    > mfd_remove_devices(chip->dev);
    > regmap_del_irq_chip(i2c->irq, chip->regmap_irq);
    >

    --
    Lee Jones [李琼斯]
    Principal Technical Lead - Developer Services
    Linaro.org │ Open source software for Arm SoCs
    Follow Linaro: Facebook | Twitter | Blog

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