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

[Manivannan Sadhasivam]

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@xxxxxxxxxxxxxxxx>
> > > ---
> > >   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.

- Mani

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