Re: [PATCH v2 00/11] scsi: ufs: Add TX Equalization support for UFS 5.0

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

On 3/5/2026 11:04 PM, Bean Huo wrote:
> Can,
>
> On Wed, 2026-03-04 at 05:53 -0800, Can Guo wrote:
>> Hi,
>>
>> The UFS 5.0 standard was published today,
> Myabe replace time sensitive wording “published today” with stable wording?
That is also my plan for next version, thanks!
>
>
>> introducing support for HS-G6
>> (23.2 Gbps per lane) through the new UniPro V3.0 interconnect layer and
>> M-PHY V6.0 physical layer specifications. To achieve reliable operation
>> at these higher speeds, UniPro V3.0 introduces TX Equalization and
>> Pre-Coding mechanisms that are essential for signal integrity.
>>
>> This patch series implements TX Equalization support in the UFS core
>> driver as specified in UFSHCI v5.0, along with the necessary vendor
>> operations and a reference implementation for Qualcomm UFS host
>> controllers.
>>
>> Background
>> ==========
>>
>> TX Equalization is a signal conditioning technique that compensates for
>> channel impairments at high data rates (HS-G4 through HS-G6). It works
>> by adjusting two key parameters:
>>
>> - PreShoot: Pre-emphasis applied before the main signal transition
>> - DeEmphasis: De-emphasis applied after the main signal transition
>>
>> UniPro V3.0 defines TX Equalization Training (EQTR) procedure to
>> automatically discover optimal TX Equalization settings. The EQTR
>> procedure:
>>
>> 1. Starts from the most reliable link state (HS-G1)
>> 2. Iterates through all possible PreShoot and DeEmphasis combinations
>> 3. Evaluates signal quality using Figure of Merit (FOM) measurements
>> 4. Selects the best settings for both host and device TX lanes
>>
> what happens when EQTR fails, mabye you have this comments in the patch.
This is a good question. In this version, once TX EQTR fails, 
ufshcd_config_pwr_mode()
would bail with error before calling ufshcd_change_power_mode(). But I 
am planning
to loosen it in next version, that is, if TX EQTR fails the TX 
Equalization settings will remain
unchanged and ufshcd_config_pwr_mode() would anyways go ahead change 
power mode.

Thanks,
Can Guo.
>
> Kind regards,
> Bean
>
>