Re: [PATCH v3 3/5] arm64: dts: ti: Add support for AM642 SoC

[Nishanth Menon <nm@ti.com>]

On 11:25-20210121, Suman Anna wrote:
> On 1/20/21 2:25 PM, Dave Gerlach wrote:
> > The AM642 SoC belongs to the K3 Multicore SoC architecture platform,
> > providing advanced system integration to enable applications such as
> > Motor Drives, PLC, Remote IO and IoT Gateways.
> > 
> > Some highlights of this SoC are:
> > * Dual Cortex-A53s in a single cluster, two clusters of dual Cortex-R5F
> >   MCUs, and a single Cortex-M4F.
> > * Two Gigabit Industrial Communication Subsystems (ICSSG).
> > * Integrated Ethernet switch supporting up to a total of two external
> >   ports.
> > * PCIe-GEN2x1L, USB3/USB2, 2xCAN-FD, eMMC and SD, UFS, OSPI memory
> >   controller, QSPI, I2C, eCAP/eQEP, ePWM, ADC, among other
> >   peripherals.
> > * Centralized System Controller for Security, Power, and Resource
> >   Management (DMSC).
> > 
> > See AM64X Technical Reference Manual (SPRUIM2, Nov 2020)
> > for further details: https://www.ti.com/lit/pdf/spruim2
> > 
> > Introduce basic support for the AM642 SoC to enable ramdisk or MMC
> > boot. Introduce the sdhci, i2c, spi, and uart MAIN domain periperhals
> > under cbass_main and the i2c, spi, and uart MCU domain periperhals
> > under cbass_mcu.
> > 
> > Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
> > Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
> 
> Hmm, there are a few pieces contributed by me, so please do add
> 
> Signed-off-by: Suman Anna <s-anna@ti.com>

Sure, thanks..

[...]

> > +
> > +	sdhci0: mmc@fa10000 {
> > +		compatible = "ti,am64-sdhci-8bit";
> 
> Hmm, I tried booting this series on top of 5.11-rc1 + Nishanth's current
> ti-k3-dts-next. So, boot of these patches using this baseline fails when using
> MMC rootfs, but is ok when using initramfs. This particular compatible and the
> corresponding driver change are only in linux-next coming through couple of
> patches from the MMC subsystem.
> 
> I am not sure why we would be including stuff that's dependent on some other
> patches being merged from a different sub-system? Strangely, this ought to be
> caught by dtbs_check, but it is not throwing any errors.
> 
> IMHO, these should only be added if you have no other external dependencies
> especially when you are applying on a 5.11-rc baseline. The MMC pull-requests
> would not go through arm-soc either.
> 

Yes, I am aware of this - this is no different from integration we have
done in the past as well.. intent is to get bindings in via subsystem
trees and dts changes via arm-soc. I always insist that basic ramdisk
boot always in the basic introduction tree. mmc, nfs are add-ons that
get added via subsystem tree and I host the dts changes - in this case
every dts node binding is fine with subsystems already queued in
linux-next. And this is no different from what I have noticed on other
ARM SoC maintainer trees as well.

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D