Re: [PATCH v2 1/5] arm64: dts: ti: k3-am6*: Set eMMC clock parents to default

Nishanth Menon
2025-04-22T12:37:54Z

On 09:36-20250421, Judith Mendez wrote:
> Hi Udit,
>
> On 4/19/25 10:00 AM, Kumar, Udit wrote:
> >
> > On 4/18/2025 5:00 AM, Judith Mendez wrote:
> > > Set eMMC clock parents to the defaults which is MAIN_PLL0_HSDIV5_CLKOUT
> > > for eMMC. This change is necessary since DM is not implementing the
> > > correct procedure to switch PLL clock source for eMMC and we have a
> > > non-glich-free mux. To remove any potential issues, lets switch back to
> > > the defaults.
> >
> > IMO, we need to fix DM  if not then documentation [0] .
>
> DM cannot be fixed for only one IP and documentation says what clock
> parents are supported, it does not have to say what are the issues
> that come with using a specific clock parent.

As I understand the arasan IP requirement is that the IP must be held in
reset while the clock is switched, which is not reasonable to implement
given decoupled systems like DM and Linux OS.

>
> >
> > Then only this patch is ok because as per document [0]
> >
> > removed clock by this patch is valid parent for eMMC.
>
> The clock parent currently set is a valid parent, but we have non-
> glitch-free muxes and to avoid any potential issues with these, we
> should switch back to the defaults. It seems like we randomly switched
> from the default for no good reason and it has been copy paste per
> platforms since then, so we are switching back to the defaults now.
>
> ~ Judith
>
> >
> > [0] https://software-dl.ti.com/tisci/esd/latest/5_soc_doc/j722s/clocks.html
> >
> > Thanks
> >
> > Udit
> >
> > >
> > > Fixes: c37c58fdeb8a ("arm64: dts: ti: k3-am62: Add more peripheral
> > > nodes")
> > > Fixes: d3ae4e8d8b6a ("arm64: dts: ti: k3-am62a-main: Add sdhci0
> > > instance")
> > > Fixes: b5080c7c1f7e ("arm64: dts: ti: k3-am62p: Add nodes for more IPs")

Please follow ./Documentation/process/stable-kernel-rules.rst - this is
easier to backport if these were to be split into 3 different patches.
Please do not forget to add Cc: stable@vger.kernel.org as per the rules
as well.

> > > Signed-off-by: Judith Mendez <jm@ti.com>
> > > ---
> > >   arch/arm64/boot/dts/ti/k3-am62-main.dtsi               | 2 --
> > >   arch/arm64/boot/dts/ti/k3-am62a-main.dtsi              | 2 --
> > >   arch/arm64/boot/dts/ti/k3-am62p-j722s-common-main.dtsi | 2 --
> > >   3 files changed, 6 deletions(-)
> > >
> > > [..]
>

--
Regards,
Nishanth Menon
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