Re: [PATCH RFC 2/2] usb: typec: ucsi: increase timeout for PPM reset operations

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Thu, Feb 06, 2025 at 09:43:15PM +0300, Fedor Pchelkin wrote:
> It is observed that on some systems an initial PPM reset during the boot
> phase can trigger a timeout:
> 
> [    6.482546] ucsi_acpi USBC000:00: failed to reset PPM!
> [    6.482551] ucsi_acpi USBC000:00: error -ETIMEDOUT: PPM init failed
> 
> Still, increasing the timeout value, albeit being the most straightforward
> solution, eliminates the problem: the initial PPM reset may take up to
> ~8000-10000ms on some Lenovo laptops. When it is reset after the above
> period of time (or even if ucsi_reset_ppm() is not called overall), UCSI
> works as expected.
> 
> Moreover, if the ucsi_acpi module is loaded/unloaded manually after the
> system has booted, reading the CCI values and resetting the PPM works
> perfectly, without any timeout. Thus it's only a boot-time issue.
> 
> The reason for this behavior is not clear but it may be the consequence
> of some tricks that the firmware performs or be an actual firmware bug.
> As a workaround, increase the timeout to avoid failing the UCSI
> initialization prematurely.
> 
> Fixes: b1b59e16075f ("usb: typec: ucsi: Increase command completion timeout value")
> Cc: stable@vger.kernel.org
> Signed-off-by: Fedor Pchelkin <boddah8794@gmail.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  drivers/usb/typec/ucsi/ucsi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index 0fe1476f4c29..7a56d3f840d7 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -25,7 +25,7 @@
>   * difficult to estimate the time it takes for the system to process the command
>   * before it is actually passed to the PPM.
>   */
> -#define UCSI_TIMEOUT_MS		5000
> +#define UCSI_TIMEOUT_MS		10000
>  
>  /*
>   * UCSI_SWAP_TIMEOUT_MS - Timeout for role swap requests
> -- 
> 2.48.1

-- 
heikki