Re: [PATCH v1] arm64: dts: ti: k3-am62-verdin: Set MMC clock pins as OUTPUT

On 8/13/2026 10:47 AM, Francesco Dolcini wrote:
> On Thu, Aug 13, 2026 at 10:45:35AM -0500, Mendez, Judith wrote:
>> Hi Francesco,
>>
>> On 8/13/2026 8:22 AM, Francesco Dolcini wrote:
>>> +Judith
>>>
>>> On Thu, Aug 13, 2026 at 11:24:58AM +0000, [email protected] wrote:
>>>> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
>>>> - [High] Setting MMC clock pins to PIN_OUTPUT disables the receiver (RXACTIVE=0), which breaks the internal clock loopback required by the MMC controller for read operations.
>>>> --
>>>>
>>>> --- Patch [1]: [PATCH v1] arm64: dts: ti: k3-am62-verdin: Set MMC clock pins as OUTPUT ---
>>>> commit b7e315f9edd8f485234748a2f8e267539b5b0f30
>>>> Author: Francesco Dolcini <[email protected]>
>>>>
>>>> arm64: dts: ti: k3-am62-verdin: Set MMC clock pins as OUTPUT
>>>>
>>>> This commit changes the MMC clock pins for the K3 AM62x Verdin module
>>>> from PIN_INPUT to PIN_OUTPUT to match the TRM documentation, effectively
>>>> disabling the receiver (RXACTIVE = 0).
>>>>
>>>> Link: https://www.ti.com/lit/pdf/spruiv7 Rev. C: Table 12-246. MMCSDi I/O Signals [0]
>>>>
>>>>> diff --git a/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi b/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi
>>>>> index e97b2b047d104..895b1b7dcac71 100644
>>>>> --- a/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi
>>>>> +++ b/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi
>>>>> @@ -573,7 +573,7 @@ AM62X_IOPAD(0x15c, PIN_INPUT, 0)  /* (AB22) MDIO0_MDIO */ /* ETH_1_MDIO, SODIMM
>>>>>    	pinctrl_sdhci0: main-mmc0-default-pins {
>>>>>    		pinctrl-single,pins = <
>>>>>    			AM62X_IOPAD(0x220, PIN_INPUT,        0) /*  (Y3) MMC0_CMD  */
>>>>> -			AM62X_IOPAD(0x218, PIN_INPUT,        0) /* (AB1) MMC0_CLK  */
>>>>> +			AM62X_IOPAD(0x218, PIN_OUTPUT,       0) /* (AB1) MMC0_CLK  */
>>>>
>>>> [Severity: High]
>>>> Does configuring this pin as PIN_OUTPUT disable the receiver (RXACTIVE=0) and
>>>> break the internal clock loopback?
>>>>
>>>> TI MMC controllers generally rely on this internal clock loopback path to
>>>> synchronize incoming data for read operations. While the TRM documents the
>>>> logical direction of the signal to the external card, disabling the input
>>>> receiver might lead to eMMC read failures and timeouts.
>>>
>>> Judith: is sashiko right on this?
>> Changing to PIN_OUTPUT should not break anything for you on AM62x based
>> board. By default the input buffer for CLK pin is not used, CLKLB input
>> buffer is used instead. CLKLB input is already configured for you by
>> default, you should not be modifying CLKLB for MMC0 nor MMC1.
>>
>> This logic does not apply for MMC2.
> 
> What do you mean? that MMC2_CLK should stay as input?

Well, there is a reason MMC2 CLKLB pin is defined in pinmux nodes on TI
boards (: By default, MMC2 CLKLB is disabled after reset unlike MMC0 and
MMC1. If we do not enable it in software -> PIN_INPUT, then the MMCSD 
loopback clock input would not work and your MMC2 would not work.

~ Judith