Re: [PATCH 4/5] usb: typec: mux: ps883x: add a delay after writing config regs

From: Konrad Dybcio

Date: Wed Sep 02 2026 - 04:31:07 EST


On 7/18/26 7:06 PM, Jens Glathe via B4 Relay wrote:
> From: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx>
>
> The config regs seem to need a few ms to propagate the changes through the
> system (like, PLLs). This improves the hotplug dp altmode success rate
> on the Lenovo 40B0 dock to 100%.
>
> Tested with T14s G6 and 40B0 dock on the HDMI port with a type-c host cable.
>
> Assisted-by: Gemini:3
> Signed-off-by: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/usb/typec/mux/ps883x.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/usb/typec/mux/ps883x.c b/drivers/usb/typec/mux/ps883x.c
> index 3533d4f363286..3ca2952e6a0a3 100644
> --- a/drivers/usb/typec/mux/ps883x.c
> +++ b/drivers/usb/typec/mux/ps883x.c
> @@ -185,6 +185,8 @@ static int ps883x_configure(struct ps883x_retimer *retimer, int cfg0,
> return ret;
> }
>
> + usleep_range(20000, 30000);

I learned our firmware (which drives the retimer on Glymur, instead of
the OS) does that as well.

With Heikki's comment addresed:

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

Konrad