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

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Message-ID: <7bc92282-6ce3-4ae4-8eef-897df992487f@ti.com>
Date: Mon, 21 Apr 2025 09:36:28 -0500
From: Judith Mendez <jm@...com>
To: "Kumar, Udit" <u-kumar1@...com>, Nishanth Menon <nm@...com>,
        Vignesh
 Raghavendra <vigneshr@...com>
CC: Tero Kristo <kristo@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof
 Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Moteen Shah <m-shah@...com>
Subject: Re: [PATCH v2 1/5] arm64: dts: ti: k3-am6*: Set eMMC clock parents to
 default

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.

> 
> 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")
>> Signed-off-by: Judith Mendez <jm@...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(-)
>>
>> [..]