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Message-ID: <31f571dc-05d6-1206-3746-c45176abe7a8@quicinc.com>
Date:   Mon, 4 Jul 2022 18:29:15 +0530
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Subject: Re: [PATCH V15 6/9] mfd: pm8008: Use i2c_new_dummy_device() API
Content-Language: en-US
To:     Lee Jones <lee.jones@linaro.org>
CC:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        <linux-arm-msm@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <swboyd@chromium.org>,
        <quic_collinsd@quicinc.com>, <quic_subbaram@quicinc.com>,
        <quic_jprakash@quicinc.com>
References: <Yrqw1YRyCGG+d4GL@google.com>
 <4112b5af-15de-007c-fcc2-c31ce9f9e426@quicinc.com>
 <YrxtXdOsIZ5LKhdV@google.com>
 <f8e70198-d0d8-5500-2869-be9e3a34f3c1@quicinc.com>
 <Yr18M9dzTOWL0m2c@google.com>
 <de1f3f33-0a8c-eb87-694c-16ebf2835720@quicinc.com>
 <Yr6oLlmfWRkiAZG7@google.com>
 <52c6ab15-1cd8-324e-4bcc-c449d8bceb19@quicinc.com>
 <Yr66ZZqEnBApHYMA@google.com>
 <0481d3cc-4bb9-4969-0232-76ba57ff260d@quicinc.com>
 <YsLhxx+L3+GJDRyO@google.com>
From:   "Satya Priya Kakitapalli (Temp)" <quic_c_skakit@quicinc.com>
In-Reply-To: <YsLhxx+L3+GJDRyO@google.com>
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On 7/4/2022 6:19 PM, Lee Jones wrote:
> On Mon, 04 Jul 2022, Satya Priya Kakitapalli (Temp) wrote:
>
>> On 7/1/2022 2:42 PM, Lee Jones wrote:
>>> On Fri, 01 Jul 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>
>>>> On 7/1/2022 1:24 PM, Lee Jones wrote:
>>>>> On Fri, 01 Jul 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>>>
>>>>>> On 6/30/2022 4:04 PM, Lee Jones wrote:
>>>>>>> On Thu, 30 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>>>>>
>>>>>>>> On 6/29/2022 8:48 PM, Lee Jones wrote:
>>>>>>>>> On Wed, 29 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>>>>>>>
>>>>>>>>>> On 6/28/2022 1:12 PM, Lee Jones wrote:
>>>>>>>>>>> On Tue, 28 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>>>>>>>>>
>>>>>>>>>>>> On 6/27/2022 1:11 PM, Lee Jones wrote:
>>>>>>>>>>>>> On Mon, 27 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Hi Lee,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 6/20/2022 4:37 PM, Satya Priya Kakitapalli (Temp) wrote:
>>>>>>>>>>>>>>> On 6/20/2022 1:50 PM, Lee Jones wrote:
>>>>>>>>>>>>>>>> On Mon, 20 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> On 6/17/2022 2:27 AM, Lee Jones wrote:
>>>>>>>>>>>>>>>>>> On Tue, 14 Jun 2022, Satya Priya wrote:
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Use i2c_new_dummy_device() to register pm8008-regulator
>>>>>>>>>>>>>>>>>>> client present at a different address space, instead of
>>>>>>>>>>>>>>>>>>> defining a separate DT node. This avoids calling the probe
>>>>>>>>>>>>>>>>>>> twice for the same chip, once for each client pm8008-infra
>>>>>>>>>>>>>>>>>>> and pm8008-regulator.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> As a part of this define pm8008_regmap_init() to do regmap
>>>>>>>>>>>>>>>>>>> init for both the clients and define pm8008_get_regmap() to
>>>>>>>>>>>>>>>>>>> pass the regmap to the regulator driver.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Signed-off-by: Satya Priya<quic_c_skakit@quicinc.com>
>>>>>>>>>>>>>>>>>>> Reviewed-by: Stephen Boyd<swboyd@chromium.org>
>>>>>>>>>>>>>>>>>>> ---
>>>>>>>>>>>>>>>>>>> Changes in V15:
>>>>>>>>>>>>>>>>>>>           - None.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Changes in V14:
>>>>>>>>>>>>>>>>>>>           - None.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> Changes in V13:
>>>>>>>>>>>>>>>>>>>           - None.
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>           drivers/mfd/qcom-pm8008.c       | 34
>>>>>>>>>>>>>>>>>>> ++++++++++++++++++++++++++++++++--
>>>>>>>>>>>>>>>>>>>           include/linux/mfd/qcom_pm8008.h |  9 +++++++++
>>>>>>>>>>>>>>>>>>>           2 files changed, 41 insertions(+), 2 deletions(-)
>>>>>>>>>>>>>>>>>>>           create mode 100644 include/linux/mfd/qcom_pm8008.h
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>> diff --git a/drivers/mfd/qcom-pm8008.c b/drivers/mfd/qcom-pm8008.c
>>>>>>>>>>>>>>>>>>> index 569ffd50..55e2a8e 100644
>>>>>>>>>>>>>>>>>>> --- a/drivers/mfd/qcom-pm8008.c
>>>>>>>>>>>>>>>>>>> +++ b/drivers/mfd/qcom-pm8008.c
>>>>>>>>>>>>>>>>>>> @@ -9,6 +9,7 @@
>>>>>>>>>>>>>>>>>>>           #include <linux/interrupt.h>
>>>>>>>>>>>>>>>>>>>           #include <linux/irq.h>
>>>>>>>>>>>>>>>>>>>           #include <linux/irqdomain.h>
>>>>>>>>>>>>>>>>>>> +#include <linux/mfd/qcom_pm8008.h>
>>>>>>>>>>>>>>>>>>>           #include <linux/module.h>
>>>>>>>>>>>>>>>>>>>           #include <linux/of_device.h>
>>>>>>>>>>>>>>>>>>>           #include <linux/of_platform.h>
>>>>>>>>>>>>>>>>>>> @@ -57,6 +58,7 @@ enum {
>>>>>>>>>>>>>>>>>>>           struct pm8008_data {
>>>>>>>>>>>>>>>>>>>               struct device *dev;
>>>>>>>>>>>>>>>>>>> +    struct regmap *regulators_regmap;
>>>>>>>>>>>>>>>>>>>               int irq;
>>>>>>>>>>>>>>>>>>>               struct regmap_irq_chip_data *irq_data;
>>>>>>>>>>>>>>>>>>>           };
>>>>>>>>>>>>>>>>>>> @@ -150,6 +152,12 @@ static struct regmap_config
>>>>>>>>>>>>>>>>>>> qcom_mfd_regmap_cfg = {
>>>>>>>>>>>>>>>>>>>               .max_register    = 0xFFFF,
>>>>>>>>>>>>>>>>>>>           };
>>>>>>>>>>>>>>>>>>> +struct regmap *pm8008_get_regmap(const struct pm8008_data *chip)
>>>>>>>>>>>>>>>>>>> +{
>>>>>>>>>>>>>>>>>>> +    return chip->regulators_regmap;
>>>>>>>>>>>>>>>>>>> +}
>>>>>>>>>>>>>>>>>>> +EXPORT_SYMBOL_GPL(pm8008_get_regmap);
>>>>>>>>>>>>>>>>>> Seems like abstraction for the sake of abstraction.
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>> Why not do the dereference inside the regulator driver?
>>>>>>>>>>>>>>>>> To derefer this in the regulator driver, we need to have the
>>>>>>>>>>>>>>>>> pm8008_data
>>>>>>>>>>>>>>>>> struct definition in the qcom_pm8008 header file.
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> I think it doesn't look great to have only that structure in
>>>>>>>>>>>>>>>>> header and all
>>>>>>>>>>>>>>>>> other structs and enum in the mfd driver.
>>>>>>>>>>>>>>>> Then why pass 'pm8008_data' at all?
>>>>>>>>>>>>>>> There is one more option, instead of passing the pm8008_data, we could
>>>>>>>>>>>>>>> pass the pdev->dev.parent and get the pm8008 chip data directly in the
>>>>>>>>>>>>>>> pm8008_get_regmap() like below
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> struct regmap *pm8008_get_regmap(const struct device *dev)
>>>>>>>>>>>>>>>         {
>>>>>>>>>>>>>>>             const struct pm8008_data *chip = dev_get_drvdata(dev);
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>             return chip->regulators_regmap;
>>>>>>>>>>>>>>> }
>>>>>>>>>>>>>>> EXPORT_SYMBOL_GPL(pm8008_get_regmap);
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> By doing this we can avoid having declaration of pm8008_data also in the
>>>>>>>>>>>>>>> header. Please let me know if this looks good.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Could you please confirm on this?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> What's preventing you from passing 'regmap'?
>>>>>>>>>>>>>>> I didn't get what you meant here, could you please elaborate a bit?
>>>>>>>>>>>>> Ah yes.  I authored you a patch, but became distracted. Here:
>>>>>>>>>>>>>
>>>>>>>>>>>>> -----8<--------------------8<-------
>>>>>>>>>>>>>
>>>>>>>>>>>>> From: Lee Jones<lee.jones@linaro.org>
>>>>>>>>>>>>>
>>>>>>>>>>>>> mfd: pm8008: Remove driver data structure pm8008_data
>>>>>>>>>>>>> Maintaining a local driver data structure that is never shared
>>>>>>>>>>>>> outside of the core device is an unnecessary complexity.  Half of the
>>>>>>>>>>>>> attributes were not used outside of a single function, one of which
>>>>>>>>>>>>> was not used at all.  The remaining 2 are generic and can be passed
>>>>>>>>>>>>> around as required.
>>>>>>>>>>>> Okay, but we still need to store the regulators_regmap, which is required in
>>>>>>>>>>>> the pm8008 regulator driver. Could we use a global variable for it?
>>>>>>>>>>> Look down ...
>>>>>>>>>>>
>>>>>>>>>>>>> Signed-off-by: Lee Jones<lee.jones@linaro.org>
>>>>>>>>>>>>> ---
>>>>>>>>>>>>>         drivers/mfd/qcom-pm8008.c | 53 ++++++++++++++++++-----------------------------
>>>>>>>>>>>>>         1 file changed, 20 insertions(+), 33 deletions(-)
>>>>>>>>>>>>>
>>>>>>>>>>>>> diff --git a/drivers/mfd/qcom-pm8008.c b/drivers/mfd/qcom-pm8008.c
>>>>>>>>>>>>> index c472d7f8103c4..4b8ff947762f2 100644
>>>>>>>>>>>>> --- a/drivers/mfd/qcom-pm8008.c
>>>>>>>>>>>>> +++ b/drivers/mfd/qcom-pm8008.c
>>>>>>>>>>>>> @@ -54,13 +54,6 @@ enum {
>>>>>>>>>>>>>         #define PM8008_PERIPH_OFFSET(paddr)	(paddr - PM8008_PERIPH_0_BASE)
>>>>>>>>>>>>> -struct pm8008_data {
>>>>>>>>>>>>> -	struct device *dev;
>>>>>>>>>>>>> -	struct regmap *regmap;
>>>>>>>>>>>>> -	int irq;
>>>>>>>>>>>>> -	struct regmap_irq_chip_data *irq_data;
>>>>>>>>>>>>> -};
>>>>>>>>>>>>> -
>>>>>>>>>>>>>         static unsigned int p0_offs[] = {PM8008_PERIPH_OFFSET(PM8008_PERIPH_0_BASE)};
>>>>>>>>>>>>>         static unsigned int p1_offs[] = {PM8008_PERIPH_OFFSET(PM8008_PERIPH_1_BASE)};
>>>>>>>>>>>>>         static unsigned int p2_offs[] = {PM8008_PERIPH_OFFSET(PM8008_PERIPH_2_BASE)};
>>>>>>>>>>>>> @@ -150,7 +143,7 @@ static struct regmap_config qcom_mfd_regmap_cfg = {
>>>>>>>>>>>>>         	.max_register	= 0xFFFF,
>>>>>>>>>>>>>         };
>>>>>>>>>>>>> -static int pm8008_init(struct pm8008_data *chip)
>>>>>>>>>>>>> +static int pm8008_init(struct regmap *regmap)
>>>>>>>>>>>>>         {
>>>>>>>>>>>>>         	int rc;
>>>>>>>>>>>>> @@ -160,34 +153,31 @@ static int pm8008_init(struct pm8008_data *chip)
>>>>>>>>>>>>>         	 * This is required to enable the writing of TYPE registers in
>>>>>>>>>>>>>         	 * regmap_irq_sync_unlock().
>>>>>>>>>>>>>         	 */
>>>>>>>>>>>>> -	rc = regmap_write(chip->regmap,
>>>>>>>>>>>>> -			 (PM8008_TEMP_ALARM_ADDR | INT_SET_TYPE_OFFSET),
>>>>>>>>>>>>> -			 BIT(0));
>>>>>>>>>>>>> +	rc = regmap_write(regmap, (PM8008_TEMP_ALARM_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>>>>>>>>>>>>>         	if (rc)
>>>>>>>>>>>>>         		return rc;
>>>>>>>>>>>>>         	/* Do the same for GPIO1 and GPIO2 peripherals */
>>>>>>>>>>>>> -	rc = regmap_write(chip->regmap,
>>>>>>>>>>>>> -			 (PM8008_GPIO1_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>>>>>>>>>>>>> +	rc = regmap_write(regmap, (PM8008_GPIO1_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>>>>>>>>>>>>>         	if (rc)
>>>>>>>>>>>>>         		return rc;
>>>>>>>>>>>>> -	rc = regmap_write(chip->regmap,
>>>>>>>>>>>>> -			 (PM8008_GPIO2_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>>>>>>>>>>>>> +	rc = regmap_write(regmap, (PM8008_GPIO2_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>>>>>>>>>>>>>         	return rc;
>>>>>>>>>>>>>         }
>>>>>>>>>>>>> -static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
>>>>>>>>>>>>> +static int pm8008_probe_irq_peripherals(struct device *dev,
>>>>>>>>>>>>> +					struct regmap *regmap,
>>>>>>>>>>>>>         					int client_irq)
>>>>>>>>>>>>>         {
>>>>>>>>>>>>>         	int rc, i;
>>>>>>>>>>>>>         	struct regmap_irq_type *type;
>>>>>>>>>>>>>         	struct regmap_irq_chip_data *irq_data;
>>>>>>>>>>>>> -	rc = pm8008_init(chip);
>>>>>>>>>>>>> +	rc = pm8008_init(regmap);
>>>>>>>>>>>>>         	if (rc) {
>>>>>>>>>>>>> -		dev_err(chip->dev, "Init failed: %d\n", rc);
>>>>>>>>>>>>> +		dev_err(dev, "Init failed: %d\n", rc);
>>>>>>>>>>>>>         		return rc;
>>>>>>>>>>>>>         	}
>>>>>>>>>>>>> @@ -207,10 +197,10 @@ static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
>>>>>>>>>>>>>         				IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW);
>>>>>>>>>>>>>         	}
>>>>>>>>>>>>> -	rc = devm_regmap_add_irq_chip(chip->dev, chip->regmap, client_irq,
>>>>>>>>>>>>> +	rc = devm_regmap_add_irq_chip(dev, regmap, client_irq,
>>>>>>>>>>>>>         			IRQF_SHARED, 0, &pm8008_irq_chip, &irq_data);
>>>>>>>>>>>>>         	if (rc) {
>>>>>>>>>>>>> -		dev_err(chip->dev, "Failed to add IRQ chip: %d\n", rc);
>>>>>>>>>>>>> +		dev_err(dev, "Failed to add IRQ chip: %d\n", rc);
>>>>>>>>>>>>>         		return rc;
>>>>>>>>>>>>>         	}
>>>>>>>>>>>>> @@ -220,26 +210,23 @@ static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
>>>>>>>>>>>>>         static int pm8008_probe(struct i2c_client *client)
>>>>>>>>>>>>>         {
>>>>>>>>>>>>>         	int rc;
>>>>>>>>>>>>> -	struct pm8008_data *chip;
>>>>>>>>>>>>> -
>>>>>>>>>>>>> -	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
>>>>>>>>>>>>> -	if (!chip)
>>>>>>>>>>>>> -		return -ENOMEM;
>>>>>>>>>>>>> +	struct device *dev;
>>>>>>>>>>>>> +	struct regmap *regmap;
>>>>>>>>>>>>> -	chip->dev = &client->dev;
>>>>>>>>>>>>> -	chip->regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg);
>>>>>>>>>>>>> -	if (!chip->regmap)
>>>>>>>>>>>>> +	dev = &client->dev;
>>>>>>>>>>>>> +	regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg);
>>>>>>>>>>>>> +	if (!regmap)
>>>>>>>>>>>>>         		return -ENODEV;
>>>>>>>>>>>>> -	i2c_set_clientdata(client, chip);
>>>>>>>>>>>>> +	i2c_set_clientdata(client, regmap);
>>>>>>>>>>> Here ^
>>>>>>>>>> I have added a dummy device and set the client data by passing regmap, see
>>>>>>>>>> below:
>>>>>>>>>>
>>>>>>>>>> +       regulators_client = i2c_new_dummy_device(client->adapter,
>>>>>>>>>> client->addr + 1);
>>>>>>>>>> +       if (IS_ERR(regulators_client)) {
>>>>>>>>>> +               dev_err(dev, "can't attach client\n");
>>>>>>>>>> +               return PTR_ERR(regulators_client);
>>>>>>>>>> +       }
>>>>>>>>>> +
>>>>>>>>>> +       regulators_regmap = devm_regmap_init_i2c(regulators_client,
>>>>>>>>>> &qcom_mfd_regmap_cfg[1]);
>>>>>>>>>> +       if (!regmap)
>>>>>>>>>> +               return -ENODEV;
>>>>>>>>>> +
>>>>>>>>>> +       i2c_set_clientdata(client, regulators_regmap);
>>>>>>>>>>
>>>>>>>>>> Now if i try to get this regmap from regulator driver by doing
>>>>>>>>>>
>>>>>>>>>> struct regmap *regmap = dev_get_drvdata(pdev->dev.parent);
>>>>>>>>>>
>>>>>>>>>> it still gets me the regmap of pm8008@8 device and not the regulator device
>>>>>>>>>> regmap (0x9). Not sure if I'm missing something here.
>>>>>>>>> So you need to pass 2 regmap pointers?
>>>>>>>>>
>>>>>>>>> If you need to pass more than one item to the child devices, you do
>>>>>>>>> need to use a struct for that.
>>>>>>>> I need to pass only one regmap out of the two, but i am not able to retrieve
>>>>>>>> the correct regmap simply by doing i2c_set_clientdata
>>>>>>>>
>>>>>>>> probably because we are having all the child nodes under same DT node and
>>>>>>>> thus not able to distinguish based on the dev pointer
>>>>>>> You can only pull out (get) the pointer that you put in (set).
>>>>>>>
>>>>>>> Unless you over-wrote it later in the thread of execution, you are
>>>>>>> pulling out whatever regulators_regmap happens to be.
>>>>>>>
>>>>>>> Is qcom_mfd_regmap_cfg[1] definitely the one you want?
>>>>>> Yes, I need qcom_mfd_regmap_cfg[1]
>>>>>>
>>>>>> Pasting code snippet for reference:
>>>>>>
>>>>>> static struct regmap_config qcom_mfd_regmap_cfg[2] = {
>>>>>>         {
>>>>>>
>>>>>>             .name = "infra",
>>>>>>             .reg_bits   = 16,
>>>>>>             .val_bits   = 8,
>>>>>>             .max_register   = 0xFFFF,
>>>>>>         },
>>>>>>         {
>>>>>>             .name = "regulators",
>>>>>>             .reg_bits   = 16,
>>>>>>             .val_bits   = 8,
>>>>>>             .max_register   = 0xFFFF,
>>>>>>         },
>>>>>>
>>>>>> };
>>>>>>
>>>>>>
>>>>>> Inside pm8008_probe:
>>>>>>
>>>>>>
>>>>>>         regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg[0]);
>>>>>>         if (!regmap)
>>>>>>             return -ENODEV;
>>>>>>
>>>>>>         i2c_set_clientdata(client, regmap);
>>>>>>
>>>>>>
>>>>>>         regulators_client = i2c_new_dummy_device(client->adapter, client->addr
>>>>>> + 1);
>>>>>>         if (IS_ERR(regulators_client)) {
>>>>>>             dev_err(dev, "can't attach client\n");
>>>>>>             return PTR_ERR(regulators_client);
>>>>>>         }
>>>>>>
>>>>>>         regulators_regmap = devm_regmap_init_i2c(regulators_client,
>>>>>> &qcom_mfd_regmap_cfg[1]);
>>>>>>         if (!regmap)
>>>>>>             return -ENODEV;
>>>>>>
>>>>>>         i2c_set_clientdata(regulators_client, regulators_regmap);
>>>>> You can't call this twice.
>>>>>
>>>>> Doing so with over-write regmap with regulators_regmap.
>>>>>
>>>>> You said you only needed one?
>>>>>
>>>>>      "I need to pass only one regmap out of the two, but i am not able to retrieve"
>>>> I thought you asked whether we have to pass two regmaps to the child
>>>> regulator driver.
>>> Yes, that's what I was asking.
>>>
>>> So you only need to pass 'regulators_regmap' (derived from
>>> "regulators") right?
>>
>> Yes
>>
>>
>>> In that case, keep:
>>>
>>>     i2c_set_clientdata(regulators_client, regulators_regmap);
>>>
>>> ... and drop:
>>>
>>>     i2c_set_clientdata(client, regmap);
>>
>> Dropping this did not help, it says regmap is NULL. Can we drop this? we
> If it's NULL coming out, it was NULL going in.
>
> Does it get checked before setting it?
>
> Are you getting it from the right device?
>
>> might still need it for other child peripherals like gpios?
>>
>> Also, setting the data through different clients would still overwrite the
>> data? I thought it would be written to respective client->dev.
> It does, but you are fetching it back out from the parent, right?
>
>    const struct pm8008_data *chip = dev_get_drvdata(pdev->dev.parent);
>
> Which is only one device.
>
> If you want to set the child's data, then that is usually accomplished
> using platform_data (you can do this using the MFD API - see struct
> mfd_cell), not driver_data.
>
>>>>>> In qcom-pm8008-regulator.c I tried to get the regmap using
>>>>>>
>>>>>> dev_get_regmap(pdev->dev.parent, "regulators");
>>>>> I haven't looked at this API before.  I suggest that this would be
>>>>> used *instead* of passing the regmap pointer via driver_data.
>>>>>
>>>>> It looks like you're using different devices to init your regmaps;
>>>>> 'client' and 'regulator_client' (derived from client->adapter).
>>>>>
>>>>> "regulators" is registered using regulators_regmap which was *not*
>>>>> init'ed with pdev->dev.parent (same as client->dev), so trying to
>>>>> dev_get_regmap() with that device pointer will not work.
>>>> Okay, So I will leave the driver as is then?
>>> Right, let's take a step back and try to clarify a few things here.
>>>
>>> What is the purpose of the two regmaps that you're creating here?
>> The pm8008 chip is an I2C based pmic which has 2 address spaces 0x8 and 0x9.
>>
>>> Where will each of them be used?
>> Under the 0x8 address space peripherals like gpio, temp-alarm etc will be
>> present and under the 0x9 regulators are present.
>>
>>> Regmaps created in MFD are usually either used only locally, here in
>>> the parent driver or shared amongst *multiple* children.  If that is
>>> not the case for regulators_regmap, which looks suspiciously like it's
>>> only used in the Regulator driver, then why not initialise the regmap
>>> there instead?  Rather than pointlessly creating it here and passing
>>> it via the driver_data pointer.
>>
>> Initially we implemented below design
>>
>> [V4,5/6] arm64: dts: qcom: pm8008: Add base dts file - Patchwork
>> (kernel.org) <https://patchwork.kernel.org/project/linux-arm-msm/patch/1637314953-4215-6-git-send-email-quic_c_skakit@quicinc.com/>
>>
>> As per Mark's suggestions I've dropped the compatible for regulator driver
>> and registered the regulators through mfd driver.
> If the regmap is _only_ used in the regulator driver, it should be
> initialised there.
>
> I suggest you move all of this regmap set-up into the Regulator
> driver and have done with it.
>
>> [V4,2/6] dt-bindings: regulator: Add pm8008 regulator bindings - Patchwork
>> (kernel.org) <https://patchwork.kernel.org/project/linux-arm-msm/patch/1637314953-4215-3-git-send-email-quic_c_skakit@quicinc.com/>
>>
>> Later as per the discussions here [1] and [2], I've added this patch to use
>> i2c_new_dummy_device() API to register the regulator devices as child
>> devices to pm8008@8 node and made the DT changes suggested.
>>
>> [1] [V9,4/6] regulator: Add a regulator driver for the PM8008 PMIC -
>> Patchwork (kernel.org) <https://patchwork.kernel.org/project/linux-arm-msm/patch/1649166633-25872-5-git-send-email-quic_c_skakit@quicinc.com/>
>>
>> [2] [V10,7/9] regulator: Add a regulator driver for the PM8008 PMIC -
>> Patchwork (kernel.org) <https://patchwork.kernel.org/project/linux-arm-msm/patch/1649939418-19861-8-git-send-email-quic_c_skakit@quicinc.com/>
>>
>> To implement this approach, I had to initialize the regulator_regmap in the
>> mfd probe and pass it to the regulator driver either through driver data
>> struct or a global variable. Other mfd drivers with similar implementation
>> are following the same. please let me know if you have further queries
>> regarding this.
> It's fine for the regulator driver to be registered from here, but the
> child should do its own regmap initialisation.


Okay, but to initialize the regmap in regulator driver, I will have to 
pass the regulator_client through the pm8008_data struct right?


>>> Once I know more about your intentions, I can help you devise a plan.