linux-kernel - Re: [PATCH V13 7/9] regulator: Add a regulator driver for the PM8008 PMIC

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Message-ID: <4b9a2abe-c462-81d9-2098-d430da24f030@quicinc.com>
Date:   Mon, 30 May 2022 16:03:47 +0530
From:   "Satya Priya Kakitapalli (Temp)" <quic_c_skakit@...cinc.com>
To:     Stephen Boyd <swboyd@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
CC:     Lee Jones <lee.jones@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_collinsd@...cinc.com>,
        <quic_subbaram@...cinc.com>, <quic_jprakash@...cinc.com>
Subject: Re: [PATCH V13 7/9] regulator: Add a regulator driver for the PM8008
 PMIC


On 5/28/2022 2:32 AM, Stephen Boyd wrote:
> HTML mail? Please send plaintext next time.
>
> Quoting Satya Priya Kakitapalli (Temp) (2022-05-27 01:24:19)
>> On 5/21/2022 8:26 AM, Stephen Boyd wrote:
>>
>>      Quoting Satya Priya (2022-05-20 03:49:35)
>>
>>          diff --git a/drivers/regulator/qcom-pm8008-regulator.c b/drivers/regulator/qcom-pm8008-regulator.c
>>          new file mode 100644
>>          index 0000000..6e815c6
>>          --- /dev/null
>>          +++ b/drivers/regulator/qcom-pm8008-regulator.c
>>          @@ -0,0 +1,225 @@
>>          +// SPDX-License-Identifier: GPL-2.0-only
>>          +/* Copyright (c) 2022, The Linux Foundation. All rights reserved. */
>>          +
>>          +#include <linux/device.h>
>>          +#include <linux/kernel.h>
>>          +#include <linux/mfd/qcom_pm8008.h>
>>          +#include <linux/module.h>
>>          +#include <linux/of.h>
>>          +#include <linux/of_device.h>
>>
>>      What in of_device.h is used?
>>
>>
>> struct of_device_id
> That struct is defined in mod_devicetable.h, not of_device.h
>
>>
>>
>>          +#include <linux/platform_device.h>
>>          +#include <linux/regmap.h>
>>          +#include <linux/regulator/driver.h>
>>          +
> [...]
>>
>>          +};
>>          +
>>          +static int pm8008_regulator_get_voltage(struct regulator_dev *rdev)
>>          +{
>>          +       struct pm8008_regulator *pm8008_reg = rdev_get_drvdata(rdev);
>>          +
>>          +       return pm8008_reg->voltage_selector;
>>
>>      Can this read the hardware instead of caching the value from
>>      pm8008_regulator_set_voltage()?
>>
>>
>> I can use the regmap_bulk_read like below (which was present in the earlier
>> versions)
> Please do
>
>>          +       }
>>          +
>>          +       pm8008_reg->dev = dev;
>>          +
>>          +       rc = of_property_read_string(dev->of_node, "regulator-name", &name);
>>          +       if (rc)
>>          +               return rc;
>>          +
>>          +       /* get the required regulator data */
>>          +       for (i = 0; i < ARRAY_SIZE(reg_data); i++)
>>          +               if (strstr(name, reg_data[i].name))
>>
>>      Why not find this via reg/address instead? It would save storing the
>>      regulator name in the reg_data table.
>>
>>
>> You mean match this using base address? then we should add base address in the
>> reg_data table. We will need the name to be stored in reg_data table anyway for
>> the pm8008_reg->rdesc.of_match
> Why? Now that this driver binds to each node individually the usage of
> of_match doesn't make any sense to me. Can you set 'struct
> regulator_config::dev' instead and not set of_match?


Currently we are setting regulator_config::dev as dev->parent i.e., 
pm8008@8, because the parent supplies are present under pm8008@8, to get 
the regulators mapped correctly to the parent supplies we are using 
dev->parent.

If we do not set of_match in regulator descriptor, 
regulator_of_get_init_node() would return NULL, causing init_data to be 
NULL during regulator_register and regulators are not getting probed. 
This can be resolved, if we get the init_data during pm8008_probe 
itself. I'll do that in the next version.