linux-kernel - Re: Allwinner SID THS calibration data cell representation?

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Message-ID: <dfbe9a71-ccab-2415-fe5b-6944df721bff@gmail.com>
Date:   Mon, 25 Feb 2019 21:37:55 +0100
From:   Philipp Rossak <embed3d@...il.com>
To:     Chen-Yu Tsai <wens@...e.org>,
        Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Emmanuel Vadot <manu@...ouilliste.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jonathan Cameron <jic23@...nel.org>,
        Quentin Schulz <quentin.schulz@...tlin.com>,
        Icenowy Zheng <icenowy@...c.io>, linux-iio@...r.kernel.org,
        devicetree <devicetree@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: Allwinner SID THS calibration data cell representation?



On 19.02.19 08:54, Chen-Yu Tsai wrote:
> Sorry for resurrecting an old discussion, but since someone posted patches
> for H5 and H6, I thought we should resolve this. I'm working on patches to
> fix / replace the big-endian issue.
> 
> On Thu, Sep 6, 2018 at 7:51 PM Maxime Ripard <maxime.ripard@...tlin.com> wrote:
>>
>> On Thu, Sep 06, 2018 at 01:47:47PM +0200, Philipp Rossak wrote:
>>> On 04.09.2018 18:46, Emmanuel Vadot wrote:
>>>>> +                 /* Data cells */
>>>>> +                 thermal_calibration: calib@234 {
>>>>> +                         reg = <0x234 0x8>;
>>>>> +                 };
>>>>    You are declaring 8 bytes of calibration data but to my knowledge it's
>>>> only 2 bytes per sensor, so 2 bytes for H3.
>>>>    Am I missing something ?
>>>>
>>>>    Thanks,
>>>
>>> Emmanuel you are right, it is 2 bytes per Sensor and should be 2 bytes for
>>> H3, but the thermal calibration data field is on all chips 64 bit wide - so
>>> 8 bytes. So I'm reading here the complete calibration data field.
>>
>> Having one cell per channel would make more sense I guess.
> 
> Would it? The 2 32-bit words directly map onto the registers 0x74 / 0x78 in
> the THS. As far as the SID is concerned, their is just one consumer for this
> data, the thermal sensor. How the thermal sensor uses that data is really not
> its concern. And the thermal sensor is really just copying the data from the
> e-fuses into its registers. Nothing more.

Using 2 32-bit words for the THS would be also ok (from my perspective).
> 
> Furthermore, with the register access interface, the e-fuses are read/write
> 32 bits at a time. Seems to me it would make more sense to enforce a 32-bit
> word size, so cells should be multiples of 32 bits.
> 
For THS I'm ok with that.

> Regards
> ChenYu
> 
Regards,
Philipp