linux-kernel - RE: [PATCH 0/8] interconnect: support i.MX8MP

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Date:   Tue, 14 Jun 2022 23:38:32 +0000
From:   Peng Fan <peng.fan@....com>
To:     Lucas Stach <l.stach@...gutronix.de>,
        "Peng Fan (OSS)" <peng.fan@....nxp.com>,
        "djakov@...nel.org" <djakov@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>, Abel Vesa <abel.vesa@....com>,
        "abailon@...libre.com" <abailon@...libre.com>,
        "laurent.pinchart@...asonboard.com" 
        <laurent.pinchart@...asonboard.com>,
        "marex@...x.de" <marex@...x.de>,
        "paul.elder@...asonboard.com" <paul.elder@...asonboard.com>,
        "Markus.Niebel@...tq-group.com" <Markus.Niebel@...tq-group.com>,
        "aford173@...il.com" <aford173@...il.com>
CC:     "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH 0/8] interconnect: support i.MX8MP

Hi Lucas,

> Subject: Re: [PATCH 0/8] interconnect: support i.MX8MP
> 
> Hi Peng,
> 
> Am Montag, dem 13.06.2022 um 01:23 +0000 schrieb Peng Fan:
> > All,
> >
> > > Subject: [PATCH 0/8] interconnect: support i.MX8MP
> >
> > I am going to send out V2 this week to address the comments until now.
> > But before that I would like to see if any one has any comments on the
> > design here.
> >
> > Georgi, do you have comments on Patch 2 " interconnect: add device
> > managed bulk API"
> >
> > Lucas, since you had comments when I first use syscon to configure
> > NoC, are you ok with the design to use interconnect in this patchset?
> >
> I'm still not 100% convinced that the blk-ctrl is the right consumer for the
> interconnect, since it doesn't do any busmastering. However, the design looks
> much better than the syscon based one.
> 
> I mostly worry about being able to extend this to do more than the current
> static configuration if/when NXP decides to release more information about the
> NoC configuration options or someone reverse engineers this part of the SoC. 

I have asked internally, NoC documentation for i.MX8M* is not allowed to public.

I
> still hope that we could optimize NoC usage by setting real bandwidth and
> latency limits for the devices connected to the NoC. As the blk-ctrl doesn't have
> any clue about this right now, we can't really set any more specific requests
> than the current INT_MAX ones.

Actually looking at ATF NoC settings, the values are suggested by Design team,
Design team give SW team such a group of value and not suggest SW team
to change it. And the value in ATF not touch bandwidth registers, as you
could see from the patchset, only mode,priority,ext_control are configured.

Similar to qcom using static settings:
./drivers/interconnect/qcom/qcm2290.c:668.
.qos.qos_mode = NOC_QOS_MODE_FIXED,

I understand that people wanna tune the settings at runtime on demand.

> I guess we could extend things in this way by making the blk-ctrl not only be a
> simple consumer of the interconnect, but aggregate requests from the devices
> in the blk-ctrl domain and forward them to the NOC provider, right?

I am not sure. This patchset is actually only for init NoC settings after
power on, because the initial value is invalid.

I could think how to resolve the INT_MAX settings in next version,
For your upper suggestion, could we start after this version approved for land
in tree?


Thanks,
Peng


> 
> Regards,
> Lucas
> 
> > Thanks,
> > Peng.
> >
> > >
> > > From: Peng Fan <peng.fan@....com>
> > >
> > > This patchset is to support i.MX8MP NoC settings, i.MX8MP NoC
> > > initial value after power up is invalid, need set a valid value after related
> power domain up.
> > >
> > > This patchset also includes two patch[1,2] during my development to
> > > enable the ICC feature for i.MX8MP.
> > >
> > > I not include ddrc DVFS in this patchset, ths patchset is only to
> > > support NoC value mode/priority/ext_control being set to a valid
> > > value that suggested by i.MX Chip Design Team. The value is same as
> > > NXP downstream one inside Arm Trusted Firmware:
> > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fso
> > >
> urce.codeaurora.org%2Fexternal%2Fimx%2Fimx-atf%2Ftree%2Fplat%2Fimx%2
> > >
> Fimx8m%2Fimx&amp;data=05%7C01%7Cpeng.fan%40nxp.com%7C6cfad0fcec
> 0d472
> > >
> 408a208da4e2cd96d%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7
> C63790
> > >
> 8251778425186%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJ
> QIjoiV2
> > >
> luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=U
> vIx%
> > >
> 2BAz9rx3Z8Oy7VSCRB90O8M5VICIUaUOiTmYw%2FeI%3D&amp;reserved=0
> > > 8mp/gpc.c?h=lf_v2.4#n97
> > >
> > > A repo created here:
> > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgi
> > >
> thub.com%2FMrVan%2Flinux%2Ftree%2Fimx8mp-interconnect&amp;data=05
> %7C
> > >
> 01%7Cpeng.fan%40nxp.com%7C6cfad0fcec0d472408a208da4e2cd96d%7C68
> 6ea1d
> > >
> 3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637908251778425186%7CUnkn
> own%7CT
> > >
> WFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJX
> V
> > >
> CI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=W2iYPMJ6dn%2F4OTalTD2yqB
> Hx%2Bo3%
> > > 2BuBTuP%2BAe4bBz2Gc%3D&amp;reserved=0
> > >
> > > Peng Fan (8):
> > >   dt-bindings: interconnect: imx8m: Add bindings for imx8mp noc
> > >   interconnect: add device managed bulk API
> > >   interconnect: imx: fix max_node_id
> > >   interconnect: imx: set src node
> > >   interconnect: imx: introduce imx_icc_provider
> > >   interconnect: imx: set of_node for interconnect provider
> > >   interconnect: imx: configure NoC mode/prioriry/ext_control
> > >   interconnect: imx: Add platform driver for imx8mp
> > >
> > >  .../bindings/interconnect/fsl,imx8m-noc.yaml  |   6 +
> > >  drivers/interconnect/bulk.c                   |  34 +++
> > >  drivers/interconnect/imx/Kconfig              |   4 +
> > >  drivers/interconnect/imx/Makefile             |   2 +
> > >  drivers/interconnect/imx/imx.c                |  68 +++--
> > >  drivers/interconnect/imx/imx.h                |  25 +-
> > >  drivers/interconnect/imx/imx8mm.c             |   2 +-
> > >  drivers/interconnect/imx/imx8mn.c             |   2 +-
> > >  drivers/interconnect/imx/imx8mp.c             | 232
> > > ++++++++++++++++++
> > >  drivers/interconnect/imx/imx8mq.c             |   2 +-
> > >  include/dt-bindings/interconnect/fsl,imx8mp.h |  59 +++++
> > >  include/linux/interconnect.h                  |   6 +
> > >  12 files changed, 424 insertions(+), 18 deletions(-)  create mode
> > > 100644 drivers/interconnect/imx/imx8mp.c  create mode 100644
> > > include/dt-bindings/interconnect/fsl,imx8mp.h
> > >
> > > --
> > > 2.25.1
> >
>