linux-kernel - Re: [PATCH v3 6/7] phy: qcom-qmp-pcie: add support for ipq9574 gen3x2 PHY

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Date: Wed, 1 May 2024 00:59:37 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: mr.nuke.me@...il.com
Cc: Varadarajan Narayanan <quic_varada@...cinc.com>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konrad.dybcio@...aro.org>, Lorenzo Pieralisi <lpieralisi@...nel.org>, 
	Krzysztof Wilczyński <kw@...ux.com>, 
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Vinod Koul <vkoul@...nel.org>, 
	Kishon Vijay Abraham I <kishon@...nel.org>, Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
	linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-phy@...ts.infradead.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH v3 6/7] phy: qcom-qmp-pcie: add support for ipq9574 gen3x2 PHY

On Wed, 1 May 2024 at 00:51, <mr.nuke.me@...il.com> wrote:
>
> On 4/30/24 1:31 AM, Varadarajan Narayanan wrote:
> > On Mon, Apr 29, 2024 at 01:55:32PM +0300, Dmitry Baryshkov wrote:
> >> On Mon, 29 Apr 2024 at 09:20, Varadarajan Narayanan
> >> <quic_varada@...cinc.com> wrote:
> >>>
> >>> On Wed, Apr 17, 2024 at 12:50:49AM +0300, Dmitry Baryshkov wrote:
> >>>> On Wed, 17 Apr 2024 at 00:25, Alex G. <mr.nuke.me@...il.com> wrote:
> >>>>>
> >>>>> Hi Dmitry,
> >>>>>
> >>>>> On 4/15/24 16:25, mr.nuke.me@...il.com wrote:
> >>>>>>
> >>>>>>
> >>>>>> On 4/15/24 15:10, Dmitry Baryshkov wrote:
> >>>>>>> On Mon, 15 Apr 2024 at 21:23, Alexandru Gagniuc <mr.nuke.me@...il.com>
> >>>>>>> wrote:
> >>>>>>>>
> >>>>>>>> Add support for the gen3x2 PCIe PHY on IPQ9574, ported form downstream
> >>>>>>>> 5.4 kernel. Only the serdes and pcs_misc tables are new, the others
> >>>>>>>> being reused from IPQ8074 and IPQ6018 PHYs.
> >>>>>>>>
> >>>>>>>> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@...il.com>
> >>>>>>>> ---
> >>>>>>>>    drivers/phy/qualcomm/phy-qcom-qmp-pcie.c      | 136 +++++++++++++++++-
> >>>>>>>>    .../phy/qualcomm/phy-qcom-qmp-pcs-pcie-v5.h   |  14 ++
> >>>>>>>>    2 files changed, 149 insertions(+), 1 deletion(-)
> >>>>>>>>
> >>>>>>>
> >>>>>>> [skipped]
> >>>>>>>
> >>>>>>>> @@ -2448,7 +2542,7 @@ static inline void qphy_clrbits(void __iomem
> >>>>>>>> *base, u32 offset, u32 val)
> >>>>>>>>
> >>>>>>>>    /* list of clocks required by phy */
> >>>>>>>>    static const char * const qmp_pciephy_clk_l[] = {
> >>>>>>>> -       "aux", "cfg_ahb", "ref", "refgen", "rchng", "phy_aux",
> >>>>>>>> +       "aux", "cfg_ahb", "ref", "refgen", "rchng", "phy_aux",
> >>>>>>>> "anoc", "snoc"
> >>>>>>>
> >>>>>>> Are the NoC clocks really necessary to drive the PHY? I think they are
> >>>>>>> usually connected to the controllers, not the PHYs.
> >>>>>>
> >>>>>> The system will hang if these clocks are not enabled. They are also
> >>>>>> attached to the PHY in the QCA 5.4 downstream kernel.
> >>>>
> >>>> Interesting.
> >>>> I see that Varadarajan is converting these clocks into interconnects.
> >>>> Maybe it's better to wait for those patches to land and use
> >>>> interconnects instead. I think it would better suit the
> >>>> infrastructure.
> >>>>
> >>>> Varadarajan, could you please comment, are these interconnects
> >>>> connected to the PHY too or just to the PCIe controller?
> >>>
> >>> Sorry for the late response. Missed this e-mail.
> >>>
> >>> These 2 clks are related to AXI port clk on Aggnoc/SNOC, not
> >>> directly connected to PCIE wrapper, but it should be enabled to
> >>> generate pcie traffic.
> >>
> >> So, are they required for the PHY or are they required for the PCIe
> >> controller only?
> >
> > These 2 clks are required for PCIe controller only.
> > PCIE controller need these clks to send/receive axi pkts.
>
> Very interesting information, thank you!
>
> Dmitry, In light of this information do you want me to move these clocks
> out of the PHY and into the PCIe controller?

That's what I was thinking about.

>
> Alex
>
> > Thanks
> > Varada
> >
> >>>>> They are named "anoc_lane", and "snoc_lane" in the downstream kernel.
> >>>>> Would you like me to use these names instead?
> >>>>
> >>>> I'm fine either way.
> >>>>
> >>
> >>
> >>
> >> --
> >> With best wishes
> >> Dmitry



-- 
With best wishes
Dmitry