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

Kumar, Udit
2025-04-22T04:09:08Z

Thanks Judith

On 4/21/2025 8:06 PM, 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.
>
>>
>> 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.
>
So, if you are saying parent
3(DEV_MMCSD0_EMMCSS_XIN_CLK_PARENT_POSTDIV4_16FF_MAIN_0_HSDIVOUT5_CLK)
and
4(DEV_MMCSD0_EMMCSS_XIN_CLK_PARENT_HSDIV4_16FFT_MAIN_2_HSDIVOUT2_CLK)
can produce a glitch while
clock selection then we should document that in clocking section,
and with note, what care to be taken when above are selected as parent.
Thanks
Udit
> ~ 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@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(-)
>>>
>>> [..]
>