linux-kernel - Re: [PATCH v7 05/10] nvmem: qcom-spmi-sdam: Migrate to devm_spmi_subdevice_alloc_and

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Message-ID: <ae46b504-58d3-4042-be05-f31e9e01091b@oss.qualcomm.com>
Date: Wed, 14 Jan 2026 10:47:20 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Andy Shevchenko <andriy.shevchenko@...el.com>,
        AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: jic23@...nel.org, dlechner@...libre.com, nuno.sa@...log.com,
        andy@...nel.org, arnd@...db.de, gregkh@...uxfoundation.org,
        srini@...nel.org, vkoul@...nel.org, neil.armstrong@...aro.org,
        sre@...nel.org, sboyd@...nel.org, krzk@...nel.org,
        dmitry.baryshkov@....qualcomm.com, quic_wcheng@...cinc.com,
        melody.olvera@....qualcomm.com, quic_nsekar@...cinc.com,
        ivo.ivanov.ivanov1@...il.com, abelvesa@...nel.org,
        luca.weiss@...rphone.com, mitltlatltl@...il.com,
        krishna.kurapati@....qualcomm.com, linux-arm-msm@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-phy@...ts.infradead.org, linux-pm@...r.kernel.org,
        kernel@...labora.com
Subject: Re: [PATCH v7 05/10] nvmem: qcom-spmi-sdam: Migrate to
 devm_spmi_subdevice_alloc_and_add()

On 1/14/26 10:42 AM, Andy Shevchenko wrote:
> On Wed, Jan 14, 2026 at 10:09:45AM +0100, AngeloGioacchino Del Regno wrote:
>> Il 14/01/26 10:07, Andy Shevchenko ha scritto:
>>> On Wed, Jan 14, 2026 at 10:03:57AM +0100, AngeloGioacchino Del Regno wrote:
>>>> Il 14/01/26 10:00, Andy Shevchenko ha scritto:
>>>>> On Wed, Jan 14, 2026 at 09:59:40AM +0100, AngeloGioacchino Del Regno wrote:
>>>>>> Il 14/01/26 09:56, Andy Shevchenko ha scritto:
>>>>>>> On Wed, Jan 14, 2026 at 09:39:52AM +0100, AngeloGioacchino Del Regno wrote:
> 
> ...
> 
>>>>>>>> +	struct regmap_config sdam_regmap_config = {
>>>>>>>> +		.reg_bits = 16,
>>>>>>>> +		.val_bits = 8,
>>>>>>>
>>>>>>>> +		.max_register = 0x100,
>>>>>>>
>>>>>>> Are you sure? This might be a bad naming, but here max == the last accessible.
>>>>>>> I bet it has to be 0xff (but since the address is 16-bit it might be actually
>>>>>>> 257 registers, but sounds very weird).
>>>>>>
>>>>>> Yes, I'm sure.
>>>>>
>>>>> So, what is resided on address 0x100 ?
>>>>
>>>> I don't remember, this is research from around 5 months ago, when I've sent
>>>> the v1 of this.
>>>>
>>>> If you really want though, I can incorrectly set max_register to 0xff.
>>>
>>> Why incorrectly? Can you dig into the datasheet and check, please? We don't
>>> know what is the 0x100 address means.
>>
>> I don't have any datasheets for Qualcomm IPs.
> 
> Hmm... Can we have somebody from QC to check on this?
> Perhaps Dmitry?

0xe6 is the last usable register today

But I wouldn't mind either 0xff or 0x100 because I don't want
anyone to pull their hair out if a regmap access is dropped some day..

Konrad