linux-kernel - Re: [PATCH v4 1/2] iio: pressure: dps310: Refactor startup procedure

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <85280d48-4251-2811-b66d-092f4153fbb5@linux.ibm.com>
Date:   Tue, 6 Sep 2022 14:48:20 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     linux-iio <linux-iio@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Joel Stanley <joel@....id.au>
Subject: Re: [PATCH v4 1/2] iio: pressure: dps310: Refactor startup procedure


On 8/20/22 06:49, Jonathan Cameron wrote:
> On Fri, 19 Aug 2022 12:42:00 +0300
> Andy Shevchenko <andy.shevchenko@...il.com> wrote:
>
>> On Mon, Aug 15, 2022 at 4:42 PM Eddie James <eajames@...ux.ibm.com> wrote:
>>> On 8/12/22 17:03, Andy Shevchenko wrote:
>>>> On Wed, Aug 10, 2022 at 12:12 AM Eddie James <eajames@...ux.ibm.com> wrote:
>> ...
>>
>>>>> +       rc = regmap_write(data->regmap, 0x0e, 0xA5);
>>>>> +       if (rc)
>>>>> +               return rc;
>>>>> +
>>>>> +       rc = regmap_write(data->regmap, 0x0f, 0x96);
>>>>> +       if (rc)
>>>>> +               return rc;
>>>> This code already exists, but still want to ask, is it really
>>>> byte-registers here and not be16/le16 one? In such a case perhaps bulk
>>>> write can be used to reflect it better?
>>> The temperature and pressure regs are 24 bits big endian, and all the
>>> rest are 8 bits. I think the existing approach is best.
>> It doesn't look like you got what I was meaning... Or I misunderstood
>> what you said.
>>
>> The code above writes two byte values to two sequential registers
>> which make me think that they are 16-bit registers at offset 0x0e.
> Given they are undocumented, this is guessing territory.
> Probably best to just leave them as is.
> You could do a bulk write on an array though as that implies
> nothing about what's in the registers -just that they happen
> to be next to each other.


Indeed. Is it worth it to switch to bulk write for two 2-byte writes? 
I'm inclined to say no and will leave this as-is for v6, but if you 
think it is, I can switch it.


Thanks,

Eddie


>
>> ...
>>
>>>>> +       rc = regmap_write(data->regmap, 0x0e, 0x00);
>>>>> +       if (rc)
>>>>> +               return rc;
>>>>> +
>>>>> +       return regmap_write(data->regmap, 0x0f, 0x00);
>> Ditto.
>>