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

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

On 5/27/2026 5:24 PM, Can Guo wrote:
>
>
> On 5/27/2026 5:15 PM, Manivannan Sadhasivam wrote:
>> 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...>,
> Man, I don't like that way to be honest, it took me a few minutes to 
> understand it on the PCIe side...
>
> Let's go with my approach please...
I misunderstood your point. I thought you meant the 0x5555 vs 0x55 
stuffs in PCIe side.
I am OK to go with single tuple approach as you suggested, which is more 
readable.

Thanks,
Can Guo.
> Thanks,
> Can Guo.
>>
>> - Mani
>>
>