linux-kernel - Re: [PATCH] usb: typec: ucsi: Wait 20ms before retrying reset

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Message-ID: <2024032624-subtitle-crisped-f4f1@gregkh>
Date: Tue, 26 Mar 2024 09:29:27 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Pavan Holla <pholla@...omium.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Subject: Re: [PATCH] usb: typec: ucsi: Wait 20ms before retrying reset

On Mon, Mar 25, 2024 at 09:19:43PM +0000, Pavan Holla wrote:
> The PPM might take time to process reset. Allow 20ms for the reset to
> complete before issuing another reset.
> 
> Signed-off-by: Pavan Holla <pholla@...omium.org>

What commit id does this fix?  Does it need to go to older kernels?

> ---
> There is a 20ms delay for a reset retry to complete. However, the first
> reset attempt is expected to complete immediately after an async write
> of the reset command. This patch adds 20ms between the async write and
> the CCI read that expects the reset to be complete. The additional delay
> also allows the PPM to settle after the first reset, which seems to be
> the intention behind the original 20ms delay ( kernel v4.14 has a comment
> regarding the same )

Why was the comment removed in newer kernels?

Where does the magic 20ms number come from?  What about systems that do
not need that time delay, did things just slow down for them?

thanks,

greg k-h