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

[Manivannan Sadhasivam]

On Wed, May 27, 2026 at 04:51:04PM +0800, Can Guo wrote:
> 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>;
> 

How about encoding Host and Device values in a single tuple. Like,

	txeq-preshoot-g6 = <Lane_0 Host_PreShoot Device_PreShoot>, <Lane 1...>,

- Mani

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