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From:   Billy Laws <blaws05@gmail.com>
Date:   Tue, 29 Jan 2019 13:33:46 +0000
Message-ID: <CAFUUQHN=mge+RFWssYJDc9PiVGo5XtcZLwjek-xNbxmFX0tPUA@mail.gmail.com>
Subject: Re: [2/2] mfd: max77620: Add low battery monitor support
To:     Mark Zhang <markz@nvidia.com>
Cc:     Lee Jones <lee.jones@linaro.org>, linux-kernel@vger.kernel.org,
        linux-tegra@vger.kernel.org,
        Laxman Dewangan <ldewangan@nvidia.com>,
        Venkat Reddy Talla <vreddytalla@nvidia.com>
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It does, see this article
https://blog.quendi.moe/2018/07/03/en-debugging-nintendo-switch-linux-power-management-battery-desync-edition/


On Tue, Jan 29, 2019 at 9:03 AM Mark Zhang <markz@nvidia.com> wrote:
>
> On 1/29/2019 3:36 PM, Billy Laws wrote:
> > Sure, that's fine with me, will send then this gets accepted. Two
> > other things: you should probably set the reg to 0 if the property
> > isn't specified as regmap_add_irqchip sets it to 0xff (basically all
> > enabled on highest limit), and you haven't updated the dt-bindings.
>
> Billy, v2 is out, dt-bindings patches are added.
> But after a second thought, I don't think regmap_add_irqchip might set
> registers to 0xff. I mean, for 2 registers which this patch set touches,
> they're not IRQ registers(mask/status/...), so regmap_add_irqchip should
> not touch them so I didn't make changes to driver codes in v2.
>
> Mark
>
> >
> > On Tue, Jan 29, 2019 at 6:52 AM Mark Zhang <markz@nvidia.com> wrote:
> >>
> >> On 1/27/2019 10:54 PM, Billy Laws wrote:
> >>>  >This patch adds PMIC configurations for low-battery
> >>>  >monitoring by handling max77620 register CNFGGLBL1.
> >>>  >
> >>> It might be an idea to add lbhyst configuration here and support using
> >>> custom lbdac values to specify a different cutoff point.
> >>
> >> Yeah this patch doesn't have support to program LBHYST & LBDAC because
> >> according to our experiences, we don't have requirement to modify them
> >> when low battery monitor support added.
> >>
> >> I think we can create a new patch to support these 2 fields in the future
> >> when we really need them. Or you can create a patch if you have requirement
> >> for them, is this OK to you Billy?
> >>
> >> Mark
> >>
> >>>
> >>> See: https://datasheetspdf.com/pdf-file/924230/Maxim/MAX8698C/1  pg 46
> >>>  >Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
> >>>  >Signed-off-by: Venkat Reddy Talla <vreddytalla@nvidia.com>
> >>>  >Signed-off-by: Mark Zhang <markz@nvidia.com>
> >>>  >---
> >>>  > drivers/mfd/max77620.c | 57 +++++++++++++++++++++++++++++++++++++++++-
> >>>  > 1 file changed, 56 insertions(+), 1 deletion(-)
> >>>  >
> >>>  >diff --git a/drivers/mfd/max77620.c b/drivers/mfd/max77620.c
> >>>  >index f58143103185..9e50d145afd8 100644
> >>>  >--- a/drivers/mfd/max77620.c
> >>>  >+++ b/drivers/mfd/max77620.c
> >>>  >@@ -474,6 +474,57 @@ static int
> >>> max77620_init_backup_battery_charging(struct max77620_chip *chip)
> >>>  >  return ret;
> >>>  > }
> >>>  >
> >>>  >+static int max77620_init_low_battery_monitor(struct max77620_chip *chip)
> >>>  >+{
> >>>  >+ struct device *dev = chip->dev;
> >>>  >+ struct device_node *np;
> >>>  >+ bool pval;
> >>>  >+ u8 mask = 0;
> >>>  >+ u8 val = 0;
> >>>  >+ int ret;
> >>>  >+
> >>>  >+ np = of_get_child_by_name(dev->of_node, "low-battery-monitor");
> >>>  >+ if (!np) {
> >>>  >+ dev_info(dev, "Low battery monitoring support disabled\n");
> >>>  >+ return 0;
> >>>  >+ }
> >>>  >+
> >>>  >+ pval = of_property_read_bool(np, "maxim,low-battery-dac-enable");
> >>>  >+ if (pval) {
> >>>  >+ mask |= MAX77620_CNFGGLBL1_LBDAC_EN;
> >>>  >+ val |= MAX77620_CNFGGLBL1_LBDAC_EN;
> >>>  >+ }
> >>>  >+
> >>>  >+ pval = of_property_read_bool(np, "maxim,low-battery-dac-disable");
> >>>  >+ if (pval)
> >>>  >+ mask |= MAX77620_CNFGGLBL1_LBDAC_EN;
> >>>  >+
> >>>  >+ pval = of_property_read_bool(np, "maxim,low-battery-shutdown-enable");
> >>>  >+ if (pval) {
> >>>  >+ mask |= MAX77620_CNFGGLBL1_MPPLD;
> >>>  >+ val |= MAX77620_CNFGGLBL1_MPPLD;
> >>>  >+ }
> >>>  >+
> >>>  >+ pval = of_property_read_bool(np, "maxim,low-battery-shutdown-disable");
> >>>  >+ if (pval)
> >>>  >+ mask |= MAX77620_CNFGGLBL1_MPPLD;
> >>>  >+
> >>>  >+ pval = of_property_read_bool(np, "maxim,low-battery-reset-enable");
> >>>  >+ if (pval) {
> >>>  >+ mask |= MAX77620_CNFGGLBL1_LBRSTEN;
> >>>  >+ val |= MAX77620_CNFGGLBL1_LBRSTEN;
> >>>  >+ }
> >>>  >+
> >>>  >+ pval = of_property_read_bool(np, "maxim,low-battery-reset-disable");
> >>>  >+ if (pval)
> >>>  >+ mask |= MAX77620_CNFGGLBL1_LBRSTEN;
> >>>  >+
> >>>  >+ ret = regmap_update_bits(chip->rmap, MAX77620_REG_CNFGGLBL1, mask, val);
> >>>  >+ if (ret < 0)
> >>>  >+ dev_err(dev, "Reg CNFGGLBL1 update failed: %d\n", ret);
> >>>  >+ return ret;
> >>>  >+}
> >>>  >+
> >>>  > static int max77620_read_es_version(struct max77620_chip *chip)
> >>>  > {
> >>>  >  unsigned int val;
> >>>  >@@ -563,7 +614,11 @@ static int max77620_probe(struct i2c_client *client,
> >>>  >  if (ret < 0)
> >>>  >  return ret;
> >>>  >
> >>>  >- ret =  devm_mfd_add_devices(chip->dev, PLATFORM_DEVID_NONE,
> >>>  >+ ret = max77620_init_low_battery_monitor(chip);
> >>>  >+ if (ret < 0)
> >>>  >+ return ret;
> >>>  >+
> >>>  >+ ret = devm_mfd_add_devices(chip->dev, PLATFORM_DEVID_NONE,
> >>>  >      mfd_cells, n_mfd_cells, NULL, 0,
> >>>  >      regmap_irq_get_domain(chip->top_irq_data));
> >>>  >  if (ret < 0) {
> >>>