linux-kernel - Re: [PATCH v2] usb: typec: ucsi: Wait 20ms before reading CCI after a reset

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Date: Wed, 3 Apr 2024 15:22:09 -0700
From: Prashant Malani <pmalani@...omium.org>
To: Pavan Holla <pholla@...omium.org>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, linux-usb@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Subject: Re: [PATCH v2] usb: typec: ucsi: Wait 20ms before reading CCI after a reset

Hi Pavan,

On Wed, Apr 3, 2024 at 10:57 AM Pavan Holla <pholla@...omium.org> wrote:
>
> The PPM might take time to process a reset. Allow 20ms for the reset to
> be processed before reading the CCI.
>
> Signed-off-by: Pavan Holla <pholla@...omium.org>
> ---
> The PPM might take time to process a reset and set the CCI. Give the PPM
> 20ms to update it's CCI.
>
> Based on the discussion in v1, this should not slow down existing
> implementations because they would not set any bits in the CCI after a reset,
> and would take a 20ms delay to read the CCI anyway. This change just makes the
> delay explicit, and reduces a CCI read. Based on the spec, the PPM has
> 10ms to set busy, so, 20ms seems like a reasonable delay before we read
> the CCI.

The above information is helpful context, and should be included
in the commit message, otherwise it will get lost on patch application.

With that, feel free to add:
Reviewed-by: Prashant Malani <pmalani@...omium.org>

BR,

-Prashant