linux-kernel - Re: [PATCH] ARM: dts: qcom: msm8974: correct qfprom node reg

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Message-ID: <4820647.31r3eYUQgx@z3ntu.xyz>
Date:   Wed, 19 Apr 2023 18:18:01 +0200
From:   Luca Weiss <luca@...tu.xyz>
To:     ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        linux-arm-msm@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Rob Herring <robh@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Craig Tatlor <ctatlor97@...il.com>
Subject: Re: [PATCH] ARM: dts: qcom: msm8974: correct qfprom node reg

On Mittwoch, 19. April 2023 18:12:04 CEST Konrad Dybcio wrote:
> On 19.04.2023 18:00, Luca Weiss wrote:
> > Hi Konrad,
> > 
> > On Montag, 30. Jänner 2023 21:37:29 CEST Luca Weiss wrote:
> >> On Montag, 30. Jänner 2023 19:42:51 CET Konrad Dybcio wrote:
> >>> On 30.01.2023 19:36, Luca Weiss wrote:
> >>>> On Montag, 30. Jänner 2023 19:30:04 CET Konrad Dybcio wrote:
> >>>>> On 30.01.2023 19:20, luca@...tu.xyz wrote:
> >>>>>> From: Craig Tatlor <ctatlor97@...il.com>
> >>>>>> 
> >>>>>> The qfprom actually starts at 0xfc4b8000 instead of 0xfc4bc000 as
> >>>>>> defined previously. Adjust the tsens offsets accordingly.
> >>>>>> 
> >>>>>> [luca@...tu.xyz: extract to standalone patch]
> >>>>>> 
> >>>>>> Fixes: c59ffb519357 ("arm: dts: msm8974: Add thermal zones, tsens and
> >>>>>> qfprom nodes") Signed-off-by: Craig Tatlor <ctatlor97@...il.com>
> >>>>>> Signed-off-by: Luca Weiss <luca@...tu.xyz>
> >>>>>> ---
> >>>>> 
> >>>>> Isn't this a raw vs ecc-corrected values problem?
> >>>> 
> >>>> Not quite sure what you mean.
> >>> 
> >>> The QFPROM is split into two parts: one where raw values
> >>> are stored, and the other one where ECC-corrected copies
> >>> of them reside. Usually it's at offset of 0x4000. We should
> >>> generally be using the ECC-corrected ones, because.. well..
> >>> they are ECC-corrected.. You may want to check if the
> >>> fuse you're adding reads the same value at +0x4000.
> >> 
> >> Yeah that actually seems to work...
> >> 
> >> But downstream's using this +0x4000 only for tsens it seems
> >> 
> >>    <0xfc4bc000 0x1000> as "tsens_eeprom_physical"
> >> 
> >> qcom,clock-krait-8974 is using this:
> >>     <0xfc4b80b0 0x08> as "efuse"
> >> 
> >> Also seems HDMI driver is using a mix for HDCP stuff
> >> 
> >>   drivers/video/msm/mdss/mdss_hdmi_util.h:
> >>     /* QFPROM Registers for HDMI/HDCP */
> >>     #define QFPROM_RAW_FEAT_CONFIG_ROW0_LSB  (0x000000F8)
> >>     #define QFPROM_RAW_FEAT_CONFIG_ROW0_MSB  (0x000000FC)
> >>     #define HDCP_KSV_LSB                     (0x000060D8)
> >>     #define HDCP_KSV_MSB                     (0x000060DC)
> >> 
> >> Any clue why Qualcomm used it this way in downstream? I'd rather not
> >> deviate too much if not for a good reason...
> > 
> > Any comments on the above?
> 
> This thread got burried to deep in the mailbox!
> 
> I see two reasons why they could be using the uncorrected region:
> - their generators are messed up in general
> 
> - they may have had an early chip revision once where there were
>   problems with this and their generators were messed up to
>   accommodate for it and everybody forgot to fix that
> 
> No other good explanations as far as I'm aware!

So, resolution is to use the offsets as declared in downstream, so take this 
patch to have the full range available?

Regards
Luca