Re: [PATCH 1/2] arm64: dts: qcom: hamoa-iot-evk: Add eDP display overlay

On Thu, Aug 13, 2026 at 05:54:25PM +0530, Anand Tiwari wrote:
> On Mon, Aug 10, 2026 at 12:04:21PM +0300, Dmitry Baryshkov wrote:
> > On Fri, Aug 07, 2026 at 03:30:13PM +0530, Anand Tiwari wrote:
> > > On Thu, Aug 06, 2026 at 07:05:37PM -0500, Bjorn Andersson wrote:
> > > > On Thu, Aug 06, 2026 at 10:01:20PM +0530, Anand Tiwari wrote:
> > > > > Move the eDP panel configuration and related power, backlight, and pinctrl
> > > > > nodes into a separate overlay. Keep the base DTB suitable for headless
> > > > > variants and provide a composite DTB for headed variants.
> > > > 
> > > > To quote:
> > > > https://docs.kernel.org/process/submitting-patches.html#describe-your-changes
> > > > 
> > > > """
> > > > Describe your problem. Whether your patch is a one-line bug fix or 5000
> > > > lines of a new feature, there must be an underlying problem that
> > > > motivated you to do this work. Convince the reviewer that there is a
> > > > problem worth fixing and that it makes sense for them to read past the
> > > > first paragraph.
> > > > """
> > > > 
> > > > In fact, I'm not even able to guess what the problem you're fixing here.
> > > > 
> > > > Regards,
> > > > Bjorn
> > > >
> > > 
> > > The problem is that the base device trees currently describe the eDP
> > > display hardware unconditionally. However, Hamoa and Purwa IoT EVKs
> > > are also available in headless variants without an eDP panel.
> > > 
> > > With current base DTBs, headless variants are not stable where eDP panel is not
> > > physically connected with board and userspace is trying to use it.
> > 
> > Please define "are not stable"
> 
> I did not see any crash in this case but in the absence of physical panel 
> logs are flooded with errors, userspace is trying to commit the frames 
> since connector status is always connected:
> 
> "
> [   23.499621] panel-simple-dp-aux aux-aea0000.displayport-controller: Prepare 
> timeout after 5 tries
> [   23.508763] panel-simple-dp-aux aux-aea0000.displayport-controller: 
> Couldn't power on panel to ID it; using conservative timings: -110
> [   52.143157] [drm:dpu_kms_wait_for_commit_done:525] [dpu error]wait for 
> commit done returned -110
> [   52.175662] [drm:dpu_encoder_frame_done_timeout:2733] [dpu error]enc40 
> frame done timeout
> [   55.351084] [drm:dpu_encoder_helper_report_irq_timeout [msm]] *ERROR* 
> irq timeout id=40, intf_mode=INTF_MODE_VIDEO intf=5 wb=-1, pp=0, intr=0
> "
>  
> Another issue On Ubuntu with Gnome Desktop is:
> Display's connected with other DP ports are only showing backlight since 
> login UI picked eDP panel connector which is not physically connected.

So, for the next revision please describe that in the commit message.

> 
> > 
> > > This series fixes the inaccurate hardware description by keeping the
> > > base DTBs limited to hardware common to both variants and moving the
> > > eDP-specific nodes into separate overlays. The base DTB can therefore
> > > be used for headless variants, while the overlay is selected for
> > > headed variants.
> > 
> > -- 
> > With best wishes
> > Dmitry

-- 
With best wishes
Dmitry