Re: [PATCH] drm/msm/dp: Correct LeMans/Monaco DP phy Swing/Emphasis setting

[Yongxing Mou]

On 1/9/2026 5:58 PM, Konrad Dybcio wrote:
> On 1/9/26 9:30 AM, Yongxing Mou wrote:
> > Currently, the LeMans/Monaco DP PHY operates in DP mode rather than eDP
> > mode. Per the PHY HPG, the Swing and Emphasis settings have been corrected
> > to the appropriate DP-mode values.
> >
> > Additionally, the HPG specifies that the LDO value should be set to 0 when
> > in DP mode. These misconfigurations can lead to link training failures on
> > certain dongles.
> >
> > Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/phy/qualcomm/phy-qcom-edp.c | 27 ++++++++++++++++++++++++---
> >   1 file changed, 24 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/phy/qualcomm/phy-qcom-edp.c b/drivers/phy/qualcomm/phy-qcom-edp.c
> > index 13feab99feec..5b0d774bd715 100644
> > --- a/drivers/phy/qualcomm/phy-qcom-edp.c
> > +++ b/drivers/phy/qualcomm/phy-qcom-edp.c
> > @@ -122,6 +122,13 @@ static const u8 dp_swing_hbr_rbr[4][4] = {
> >   	{ 0x1f, 0xff, 0xff, 0xff }
> >   };
> >   
> > +static const u8 dp_swing_hbr_rbr_v1[4][4] = {
> > +	{ 0x07, 0x0f, 0x16, 0x1f },
> > +	{ 0x11, 0x1e, 0x1f, 0xff },
> > +	{ 0x16, 0x1f, 0xff, 0xff },
> > +	{ 0x1f, 0xff, 0xff, 0xff }
> > +};
>
> For these platforms, I see 4 tables of settings:
>
> (Low/High) Swing/Pre-em for (Low/High) HBR
>
> None of them exactly match your change
Emm, this table is in LeMans eDP HPG, here are 6 tables. 4 of them use 
for eDP mode and reset 2 tables used for DP mode. If my understanding is 
incorrect, please correct me. Thanks ~~~ > [...]
> > -	ldo_config = edp->is_edp ? 0x0 : 0x1;
> > +	ldo_config = !edp->is_edp ? 0x0 : 0x1;
>
> You'll notice that this is further wrong, because for eDP, it should be
> 0x81 at low-swing-high-HBR and 0xc1 at low-swing-low-HBR, and 0 at both
> cases of high-swing
>
> Please split the LDO change into a separate commit because it touches
> more platforms
>
> Konrad

Yes, you are right, here seems something not correct. i will separate 
this change into single one.Here are some parts I don't fully understand 
here. Could you please point it? How do we know whether it is in 
low‑swing or high‑swing. I didn’t see any logic in the current code that 
determines this. Also, the value in Hamoa seems not same with LeMans,it 
is 0x51 and 0x91.

While going through the Hamoa HPG, I noticed a potential issue.

 static struct qcom_edp_phy_cfg x1e80100_phy_cfg = {
	.aux_cfg = edp_phy_aux_cfg_v4,
	.vco_div_cfg = edp_phy_vco_div_cfg_v4,
	.swing_pre_emph_cfg = &dp_phy_swing_pre_emph_cfg,...It use 
dp_phy_swing_pre_emph_cfg not edp_phy_swing_pre_emph_cfg, but Hamoa 
really use edp-panel here.. so does this phy cfg correct here?