linux-kernel - Re: [PATCH v2] drm/msm/dp: Correct LeMans/Monaco DP phy Swing/Emphasis setting

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Message-ID: <bq4usuzu7dl42ruduy4whbgnfamgnmyj7wuyd2oa472qet6tyv@pdku43m6e45x>
Date: Tue, 20 Jan 2026 11:28:19 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Yongxing Mou <yongxing.mou@....qualcomm.com>
Cc: Vinod Koul <vkoul@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Abel Vesa <abel.vesa@....qualcomm.com>
Subject: Re: [PATCH v2] drm/msm/dp: Correct LeMans/Monaco DP phy
 Swing/Emphasis setting

On Tue, Jan 20, 2026 at 03:56:10PM +0800, Yongxing Mou wrote:
> 
> 
> On 1/20/2026 11:12 AM, Dmitry Baryshkov wrote:
> > On Tue, Jan 20, 2026 at 10:43:46AM +0800, Yongxing Mou wrote:
> > > 
> > > 
> > > On 1/19/2026 8:55 PM, Dmitry Baryshkov wrote:
> > > > On Mon, Jan 19, 2026 at 08:37:20PM +0800, Yongxing Mou wrote:
> > > > > Currently, the LeMans/Monaco devices and their derivative platforms
> > > > > operate in DP mode rather than eDP mode. Per the PHY HPG, the Swing and
> > > > > Emphasis settings need to be corrected to the proper values.
> > > > 
> > > > No, they need to be configured dynamically. I wrote earlier that the
> > > > driver needs refactoring.
> > > > 
> > > Hi, Dmitry. I plan to submit them in this order: this patch → LDO patch →
> > > refactor.
> > > Since the refactor involves more platforms and may take some time, I’d like
> > > to get this patch merged first.
> > 
> > This patch is incorrect. It trades working on some platforms (DP) vs
> > working of someo ther platforms (eDP). I don't think it is a proper fix
> > for any problem.
> > 
> Got it.. will post refactor series.

Thanks! I don't see a good way to fix your issue without restructuring
the driver.

Note, the driver has to support both older DT (which used separate -edp
and -dp compats) and the current one.

> > > > > 
> > > > > This will help achieve successful link training on some dongles.
> > > > > 
> > > > > Cc: stable@...r.kernel.org
> > > > > Fixes: 3f12bf16213c ("phy: qcom: edp: Add support for eDP PHY on SA8775P")
> > > > > Reviewed-by: Abel Vesa <abel.vesa@....qualcomm.com>
> > > > > Signed-off-by: Yongxing Mou <yongxing.mou@....qualcomm.com>
> > > > > ---
> > > > > Changes in v2:
> > > > > - Separate the LDO change out.[Konrad][Dmitry]
> > > > > - Modify the commit message.[Dmitry]
> > > > > - Link to v1: https://lore.kernel.org/r/20260109-klm_dpphy-v1-1-a6b6abe382de@oss.qualcomm.com
> > > > > ---
> > > > >    drivers/phy/qualcomm/phy-qcom-edp.c | 23 ++++++++++++++++++++++-
> > > > >    1 file changed, 22 insertions(+), 1 deletion(-)
> > > > > 
> > > > 
> > > 
> > > 
> > > -- 
> > > linux-phy mailing list
> > > linux-phy@...ts.infradead.org
> > > https://lists.infradead.org/mailman/listinfo/linux-phy
> > 
> 

-- 
With best wishes
Dmitry

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