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 5:29 PM, Manivannan Sadhasivam wrote:
> On Thu, May 28, 2026 at 04:40:59PM +0800, Can Guo wrote:
>>
>> 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.
>>
> Ok. I still see having 'is_static' is a bit of overkill, but I don't see a
> sensible way to check whether the static EQ settings are available or not.
>
> But please add a comment above the check to make it clear.
OK sir.

Thanks,
Can Guo.
>
> - Mani
>