Re: [PATCH 1/3] arm64: dts: qcom: msm8916: Add missing MDSS reset

[Konrad Dybcio]

On 9/15/25 3:28 PM, Stephan Gerhold wrote:
> On most MSM8916 devices (aside from the DragonBoard 410c), the bootloader
> already initializes the display to show the boot splash screen. In this
> situation, MDSS is already configured and left running when starting Linux.
> To avoid side effects from the bootloader configuration, the MDSS reset can
> be specified in the device tree to start again with a clean hardware state.

This is really just Linux behavior and not necessarily the effect
of specifying the reset in the DT, but w/e
> 
> The reset for MDSS is currently missing in msm8916.dtsi, which causes
> errors when the MDSS driver tries to re-initialize the registers:
> 
>  dsi_err_worker: status=6
>  dsi_err_worker: status=6
>  dsi_err_worker: status=6
>  ...
> 
> It turns out that we have always indirectly worked around this by building
> the MDSS driver as a module. Before v6.17, the power domain was temporarily
> turned off until the module was loaded, long enough to clear the register
> contents. In v6.17, power domains are not turned off during boot until
> sync_state() happens, so this is no longer working. Even before v6.17 this
> resulted in broken behavior, but notably only when the MDSS driver was
> built-in instead of a module.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 305410ffd1b2 ("arm64: dts: msm8916: Add display support")
> Signed-off-by: Stephan Gerhold <stephan.gerhold@xxxxxxxxxx>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>

Konrad