Re: [PATCH v2 1/2] dt-bindings: ufs: Document static TX Equalization settings properties

[Can Guo <can.guo@oss.qualcomm.com>]

Hi Mani,

On 5/23/2026 10:14 PM, Manivannan Sadhasivam wrote:
> On Sat, May 23, 2026 at 06:47:10AM -0700, Can Guo wrote:
>> UFS v5.0/UFSHCI v5.0 add HS-G6 support (46.6 Gbps/lane) via UniPro v3.0
>> and M-PHY v6.0. In these specs, TX Equalization is defined for all High
>> Speed Gears (not only HS-G6) to compensate channel loss and improve signal
>> integrity at high speed operation.
>>
>> For HS-G6, M-PHY uses PAM4 1b1b line coding, Pre-Coding may also be
>> required depending on channel characteristics.
>>
>> Add vendor-neutral DT patternProperties:
>> txeq-settings-g[1-6]
>>
>> Each property is a uint32 array of per-lane tuples:
>> (PreShoot, DeEmphasis, PrecodeEn)
>>
> I don't think combining all EQ settings (PreShoot, DeEmphasis, PrecodeEn) in a
> single property as opaque tuples is the right approach. These are three
> semantically distinct parameters with independent value ranges. So packing
> them into a uint32 array makes validation impossible in the schema.
>
> AFACIS, PrecodeEn is applicable only to HS-G6 (PAM4), but the proposed
> patternProperties forces it into G1-G5 tuples as well, which is semantically
> wrong.
Point taken for the PrecodeEn.
>
> PCIe binding defines one property per data rate for EQ presets:
> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/pci/pci-bus-common.yaml#L193
>
> Similarly, UFS should define one property per gear per (like, txeq-preshoot-g6,
> txeq-deemphasis-g6, txeq-precode-enable-g6,...) rather than clubbing everything
> into opaque tuples.
Thanks for the suggestion. I will go with below approach:

txeq-preshoot-g6 = <Host Lane 0 PreShoot, Device Lane 0 PreShoot, Host 
Lane 1 PreShoot, Device Lane 1 PreShoot>;
txeq-deemphasis-g6 = <Host Lane 0 DeEmphasis, Device Lane 0 DeEmphasis, 
Host Lane 1 DeEmphasis, Device Lane 1 DeEmphasis>;
txeq-precode-en-g6 = <Host Lane 0 PrecodeEn, Device Lane 0 PrecodeEn, 
Host Lane 1 PrecodeEn, Device Lane 1 PrecodeEn>;

Thanks,
Can Guo.
>
> - Mani
>