linux-kernel - Re: [PATCH] arm64: dts: ti: k3-am62a7-sk: Disable mmc Schmitt Trigger

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Message-ID: <c47697b4-6ebb-4af9-be96-c964d990835d@ti.com>
Date: Mon, 12 Jan 2026 18:29:54 -0600
From: Judith Mendez <jm@...com>
To: "Markus Schneider-Pargmann (TI.com)" <msp@...libre.com>, Nishanth Menon
	<nm@...com>, Vignesh Raghavendra <vigneshr@...com>, Tero Kristo
	<kristo@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
	<krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Alexander Sverdlin
	<alexander.sverdlin@...il.com>
CC: Vishal Mahaveer <vishalm@...com>, Kevin Hilman <khilman@...libre.com>,
	Dhruva Gole <d-gole@...com>, Sebin Francis <sebin.francis@...com>, "Kendall
 Willis" <k-willis@...com>, Akashdeep Kaur <a-kaur@...com>,
	<linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: ti: k3-am62a7-sk: Disable mmc Schmitt Trigger

On 1/6/26 10:22 AM, Markus Schneider-Pargmann (TI.com) wrote:
> Remove Schmitt Trigger from mmc pins. With Schmitt Trigger enabled
> u-boot SPL is not able to read u-boot from mmc:
> 
>      Trying to boot from MMC2
>      Error reading cluster
>      spl_load_image_fat: error reading image u-boot.img, err - -22
>      Error: -22
>      SPL: Unsupported Boot Device!
>      SPL: failed to boot from all boot devices
>      ### ERROR ### Please RESET the board ###
> 
> I bisected this issue between u-boot v2025.10 and v2026.01 and found the
> devicetree merge to be the problem. At a closer look I found the
> k3-pinctrl.h changes. Disabling the Schmitt Trigger fixes the u-boot SPL
> failure to read from mmc.

I have tested 4 AM62A SK boards and I cannot replicate the issue
you are seeing. I do not see an issue with Schmitt Trigger in U-boot
nor Linux /:

Can you please run a quick tap sweep on MMC1 and MMC0 interfaces like
so? https://gist.github.com/jmenti/f4a73a8323e44bf717c6d2c528c499ca

This will give me an idea if whether we should be talking about
revisiting characterization with ST_ENA=1.

Also, are you able to replicate the issue on more than one board? Or is
this the only board you see the issue on?

~ Judith