-----Original Message-----
From: Adam Ford <redacted>
Sent: Sunday, December 22, 2019 10:58 PM
To: Jacky Bai <ping.bai@nxp.com>
Cc: arm-soc <redacted>; Peng Fan
[off-list ref]; Rob Herring [off-list ref]; Mark Rutland
[off-list ref]; Shawn Guo [off-list ref]; Sascha
Hauer [off-list ref]; Pengutronix Kernel Team
[off-list ref]; Fabio Estevam [off-list ref];
dl-linux-imx [off-list ref]; devicetree [off-list ref];
Linux Kernel Mailing List [off-list ref]; Leonard Crestez
[off-list ref]
Subject: Re: [PATCH V2 0/7] soc: imx: Enable additional functionality of
i.MX8M Mini

On Sun, Dec 22, 2019 at 2:33 AM Jacky Bai [off-list ref] wrote:

quoted

quoted

-----Original Message-----
From: Adam Ford <redacted>
Sent: Saturday, December 21, 2019 11:07 PM
To: arm-soc <redacted>
Cc: Peng Fan <peng.fan@nxp.com>; Jacky Bai <ping.bai@nxp.com>; Rob
Herring [off-list ref]; Mark Rutland [off-list ref];
Shawn Guo [off-list ref]; Sascha Hauer
[off-list ref]; Pengutronix Kernel Team
[off-list ref]; Fabio Estevam [off-list ref];
dl-linux-imx [off-list ref]; devicetree
[off-list ref]; Linux Kernel Mailing List
[off-list ref]; Leonard Crestez
[off-list ref]
Subject: Re: [PATCH V2 0/7] soc: imx: Enable additional
functionality of i.MX8M Mini

On Fri, Dec 13, 2019 at 10:05 AM Adam Ford [off-list ref]

wrote:

quoted

quoted

quoted

The GPCv2 controller on the i.MX8M Mini is compatible with the
driver used for the i.MX8MQ except for the register locations and

names.

quoted

quoted

quoted

The GPCv2 controller is used to enable additional periperals
currently unavailable on the i.MX8M Mini.  In order to make them
function, the
GPCv2 needs to be adapted so the drivers can associate their power
domain to the GPCv2 to enable them.

This series makes one include file slightly more generic, adds the
iMX8M Mini entries, updates the bindings, adds them to the device
tree, then associates the new power domain to both the OTG and
PCIe controllers.

Some peripherals may need additional power domain drivers in the
future due to limitations of the GPC driver, but the drivers for
VPU and others are not available yet.

Before I do a V3 to address Rob's comments, I am thinking I'll drop
the items on the GPC that Jacky suggested would not work, and we
don't have drivers for those other peripherals (GPU, VPU, etc.)
anyway.  My main goal here was to try and get the USB OTG ports
working, so I'd like to enabled enough of the items on the GPC that
are similar to the i.MX8MQ and leave the more challenging items
until we have either a better driver available and/or actual
peripheral support coming.  I haven't seen LCDIF or DSI drivers pushed

upstream yet, so I doubt we'll see GPU or VPU yet until those are done.

quoted

quoted

Does anyone from the NXP team have any other comments/concerns?

If you look into NXP's release code, you will find that it is not easy
to handle the power domain more generically in GPCv2 driver for
imx8mm. That's the reason why we use SIP service to handle all the
power domain in TF-A. we tried to upstream the SIP version power
domain that can be reused for all i.MX8M, but rejected by ARM guys.
they think we need to use SCMI to implement it. as there is no SCMI over

SMC available, upstream is on the way, so the power domain for
i.MX8MM/MN is pending.

quoted

Thank you for the background. I appreciate it.

quoted

Actually, I am confused why we can't use SIP service, even if the SCMI
over SMC is ready in the future, It seems the SMCC function ID still need to

choose from SIP service function id bank.

quoted

Another concern for adding power domain support in GPCv2 is that, each
time a new SOC is added, we need to add hundred lines of code in GPCv2
driver. it is not a best way to keep driver reuse. The GPCv2 driver is
originally used for i.MX7D, then reused by i.MX8MQ, as i.MX8MQ has
very simple power domain design as i.MX7D. But for i.MX8MM, it is not the

case.

There are some entries on the 8MM which can be used the same way as the
8MM.  I have been able to get USB OTG working using the 8MQ's GPC table.

Until sometime better is available, would you entertain a limited use of the
8MQ's GPC where the device tree nodes only contain a limited number of
entries (like USB OTG) where we can re-use the similar functions 8MQ
without expanding the driver functions?  I know its not ideal, but it would be
a temporary solution unless you think the upstream power domain support is
coming quickly.  I looked through the mailing list history and it looked like
there were some attempts about
6 months ago, then it appeared to stop.

Once the newer driver is available upstream, we could then remove GPC
references from the 8MM device tree and point it to the new driver.

It would increase some limited functionality for the short term.  I know
Leonard has been working on the DDRC modifications and power reduction.
I have been trying to use them, but unsuccessful so far.

quoted

There is another concern, we don't want to export GPC module to rich OS

side, it is not a must.

What about doing it in the U-Boot stage if Linux isn't an option and ATF isn't
accepting them?

I have enabled the USB/PCIE power domain by default early before, if using the community ATF,
I think USB can work well.

BR
Jacky Bai

adam

quoted

BR
Jacky Bai

quoted

adam

quoted

quoted

quoted

Adam Ford (7):
  soc: imx: gpcv2: Rename imx8mq-power.h to imx8m-power.h
  soc: imx: gpcv2: Update imx8m-power.h to include iMX8M Mini
  soc: imx: gpcv2: add support for i.MX8M Mini SoC
  dt-bindings: imx-gpcv2: Update bindings to support i.MX8M Mini
  arm64: dts: imx8mm: add GPC power domains
  ARM64: dts: imx8mm: Fix clocks and power domain for USB OTG
  arm64: dts: imx8mm: Add PCIe support

 .../bindings/power/fsl,imx-gpcv2.txt          |   6 +-
 arch/arm64/boot/dts/freescale/imx8mm.dtsi     | 127 ++++++++-
 arch/arm64/boot/dts/freescale/imx8mq.dtsi     |   2 +-
 drivers/soc/imx/gpcv2.c                       | 246

+++++++++++++++++-

quoted

 .../power/{imx8mq-power.h => imx8m-power.h}   |  14 +
 5 files changed, 387 insertions(+), 8 deletions(-)  rename
include/dt-bindings/power/{imx8mq-power.h => imx8m-power.h} (57%)

--
2.20.1

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