Re: [PATCH 2/2] scsi: ufs: core: Add support for static TX Equalization settings

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

On 5/28/2026 4:16 PM, Manivannan Sadhasivam wrote:
> On Thu, May 28, 2026 at 03:24:37PM +0800, Can Guo wrote:
>>
>> On 5/28/2026 2:13 PM, Manivannan Sadhasivam wrote:
>>> On Wed, May 27, 2026 at 07:40:55AM -0700, Can Guo wrote:
>>>> Static TX Equalization settings and TX Precode enable indication from DT
>>>> properties txeq-preshoot-g[1-6], txeq-deemphasis-g[1-6], and
>>>> tx-precode-enable-g6 are board-specific baseline values. Values are
>>>> provided as per-lane tuples:
>>>>
>>>> <Host_Lane0 Device_Lane0>, [<Host_Lane1 Device_Lane1>]
>>>>
>>>> Parse DT u32 properties with explicit range checks by using
>>>> of_property_count_u32_elems()/of_property_read_u32_array().
>>>>
>>>> When adaptive TX Equalization is used, these static settings are not final:
>>>>
>>>> - If valid settings are retrieved from qTxEQGnSettings/wTxEQGnSettingsExt,
>>>>     those retrieved settings override static DT settings.
>>>> - If retrieval is not available/valid, TX EQTR runs and trained settings
>>>>     override static DT settings.
>>>>
>>>> So static DT settings are a fallback and are intended for cases where
>>>> adaptive TX Equalization is not enabled/used. Adaptive TX Equalization
>>>> remains the primary path when enabled.
>>>>
>>>> No behavior changes for platforms that do not provide these properties.
>>>>
>>>> Signed-off-by: Can Guo <can.guo@oss.qualcomm.com>
>>>> ---
>>>>    drivers/ufs/core/ufs-txeq.c      |   4 +-
>>>>    drivers/ufs/host/ufshcd-pltfrm.c | 128 +++++++++++++++++++++++++++++++
>>>>    include/ufs/ufshcd.h             |   2 +
>>>>    3 files changed, 133 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/ufs/core/ufs-txeq.c b/drivers/ufs/core/ufs-txeq.c
>>>> index 4b264adfdf49..634ec039e129 100644
>>>> --- a/drivers/ufs/core/ufs-txeq.c
>>>> +++ b/drivers/ufs/core/ufs-txeq.c
>>>> @@ -1297,7 +1297,7 @@ int ufshcd_config_tx_eq_settings(struct ufs_hba *hba,
>>>>    	}
>>>>    	params = &hba->tx_eq_params[gear - 1];
>>>> -	if (!params->is_valid || force_tx_eqtr) {
>>>> +	if (!params->is_valid || params->is_static || force_tx_eqtr) {
>>>>    		int ret;
>>>>    		ret = ufshcd_tx_eqtr(hba, params, pwr_mode);
>>>> @@ -1310,6 +1310,7 @@ int ufshcd_config_tx_eq_settings(struct ufs_hba *hba,
>>>>    		/* Mark TX Equalization settings as valid */
>>>>    		params->is_valid = true;
>>>>    		params->is_trained = true;
>>>> +		params->is_static = false;
>>>>    		params->is_applied = false;
>>>>    	}
>>>> @@ -1495,6 +1496,7 @@ static void ufshcd_extract_tx_eq_settings_attrs(struct ufs_hba *hba, u8 gear)
>>>>    	}
>>>>    	params->is_valid = true;
>>>> +	params->is_static = false;
>>> Maybe it's me, but I'm not able to understand how you want to apply these static
>>> EQ settings. In commit message you said, the static values should be used as a
>>> fallback, but you just check for 'params->is_static' while triggering
>>> ufshcd_tx_eqtr() which is supposed to perform adaptive TX EQ training. IMO, you
>>> don't need any check at all for applying static setting. If '(!params->is_valid
>>> || force_tx_eqtr)' condition is not satisfied, then the static setting should be
>>> used.
>> Thanks for the review.
>>
>> The distinction is between two different sources that can pre-populate
>> txeq_params with
>> is_valid set to true before ufshcd_config_tx_eq_settings() is called:
>>
>> 1. DT properties — parsed by ufshcd_pltfrm_parse_tx_eq_settings(),
>>      sets is_valid = true, is_static = true.
>> 2. UFS Attributes (qTxEQGnSettings/wTxEQGnSettingsExt) — retrieved by
>>      ufshcd_retrieve_tx_eq_settings() (introduced in the 2nd series),
>>      sets is_valid = true, is_static = false.
>>
>> Since both sources set is_valid = true, the is_valid flag alone cannot tell
>> them apart.
>> The is_static flag is the discriminator:
>>
>> - is_valid && is_static -> settings came from DT; they are a board-level
>> baseline.
>>    TX EQTR should still run to find optimal settings, which will then
>> overwrite the static ones.
>> - is_valid && !is_static -> settings came from UFS Attributes; they are
>> previously trained
> You use '&&' here, but '||' in the code. When you use '||', then I see no point
> for 'is_static' check.
The code is correct. My reply was explaining why the check is there, but not
explaining the check itself.

Original check in the code is (!params->is_valid || force_tx_eqtr).

Static TX EQ settings are valid, so '!params->is_valid' is false, TX 
EQTR would be skipped.

Update the check as (!params->is_valid || params->is_static || 
force_tx_eqtr) so TX EQTR
must run when static settings are provided.

Thanks,
Can Guo.
>
> - Mani
>