linux-kernel - R: R: [PATCH v3 08/11] devicetree: bindings: pci: document PARF params bindings

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Message-ID: <02e001d62925$dca9e9a0$95fdbce0$@gmail.com>
Date:   Wed, 13 May 2020 14:56:03 +0200
From:   <ansuelsmth@...il.com>
To:     "'Stanimir Varbanov'" <svarbanov@...sol.com>,
        "'Rob Herring'" <robh@...nel.org>
Cc:     "'Bjorn Andersson'" <bjorn.andersson@...aro.org>,
        "'Andy Gross'" <agross@...nel.org>,
        "'Bjorn Helgaas'" <bhelgaas@...gle.com>,
        "'Mark Rutland'" <mark.rutland@....com>,
        "'Lorenzo Pieralisi'" <lorenzo.pieralisi@....com>,
        "'Andrew Murray'" <amurray@...goodpenguin.co.uk>,
        "'Philipp Zabel'" <p.zabel@...gutronix.de>,
        <linux-arm-msm@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: R: R: [PATCH v3 08/11] devicetree: bindings: pci: document PARF params bindings

> On 5/12/20 6:45 PM, Rob Herring wrote:
> > On Thu, May 07, 2020 at 09:34:35PM +0200, ansuelsmth@...il.com
> wrote:
> >>> On Fri, May 01, 2020 at 12:06:15AM +0200, Ansuel Smith wrote:
> >>>> It is now supported the editing of Tx De-Emphasis, Tx Swing and
> >>>> Rx equalization params on ipq8064. Document this new optional
> params.
> >>>>
> >>>> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> >>>> ---
> >>>>  .../devicetree/bindings/pci/qcom,pcie.txt     | 36
> +++++++++++++++++++
> >>>>  1 file changed, 36 insertions(+)
> >>>>
> >>>> diff --git a/Documentation/devicetree/bindings/pci/qcom,pcie.txt
> >>> b/Documentation/devicetree/bindings/pci/qcom,pcie.txt
> >>>> index 6efcef040741..8cc5aea8a1da 100644
> >>>> --- a/Documentation/devicetree/bindings/pci/qcom,pcie.txt
> >>>> +++ b/Documentation/devicetree/bindings/pci/qcom,pcie.txt
> >>>> @@ -254,6 +254,42 @@
> >>>>  			- "perst-gpios"	PCIe endpoint reset signal line
> >>>>  			- "wake-gpios"	PCIe endpoint wake signal line
> >>>>
> >>>> +- qcom,tx-deemph-gen1:
> >>>> +	Usage: optional (available for ipq/apq8064)
> >>>> +	Value type: <u32>
> >>>> +	Definition: Gen1 De-emphasis value.
> >>>> +		    For ipq806x should be set to 24.
> >>>
> >>> Unless these need to be tuned per board, then the compatible string
> for
> >>> ipq806x should imply all these settings.
> >>>
> >>
> >> It was requested by v2 to make this settings tunable. These don't change
> are
> >> all the same for every ipq806x SoC. The original implementation had this
> >> value hardcoded for ipq806x. Should I restore this and drop this patch?
> >
> > Yes, please.
> 
> I still think that the values for tx deemph and tx swing should be
> tunable. But I can live with them in the driver if they not break
> support for apq8064.
> 
> The default values in the registers for apq8064 and ipq806x are:
> 
> 			default		your change
> TX_DEEMPH_GEN1		21		24
> TX_DEEMPH_GEN2_3_5DB	21		24
> TX_DEEMPH_GEN2_6DB	32		34
> 
> TX_SWING_FULL		121		120
> TX_SWING_LOW		121		120
> 
> So until now (without your change) apq8064 worked with default values.
> 

I will limit this to ipq8064(-v2) if this could be a problem.

> >
> > Rob
> >
> 
> --
> regards,
> Stan