Re: [PATCH] Enter safe mode only when pins need to be reconfigured

[Greg KH]

On Tue, Aug 23, 2022 at 10:39:49PM +0530, Rajat Khandelwal wrote:
> From: Lee Shawn C <shawn.c.lee@xxxxxxxxx>
> 
> There is no point to enter safe mode during DP/TBT configuration
> if the DP/TBT was already configured in mux. This is because safe
> mode is only applicable when there is a need to reconfigure the
> pins in order to avoid damage within/to port partner.
> 
> 1. if HPD interrupt arrives and DP mode was already configured,
> safe mode is entered again which is not desired.
> 2. in chrome systems, IOM/mux is already configured before OS
> comes up. Thus, when driver is probed, it blindly enters safe
> mode due to PD negotiations but only after gfx driver lowers
> dp_phy_ownership, will the IOM complete safe mode and send
> ack to PMC.
> Since, that never happens, we see IPC timeout.
> 
> Hence, allow safe mode only when pin reconfiguration is not
> required, which makes sense.
> 
> Signed-off-by: Rajat Khandelwal <rajat.khandelwal@xxxxxxxxx>
> Signed-off-by: Lee Shawn C <shawn.c.lee@xxxxxxxxx>

First off, don't use invalid "corp-partner.google.com" email addresses,
you know that's not going to work and just bounce everywhere and there's
no proof that this has any relationship to your intel address :(

And your signed-off-by chain is incorrect.

And most importantly, you did not follow the required Intel rules for
how to submit kernel patches.  Please go work with your internal groups
to learn what is needed and how to do this properly.  Until then, I'm
not allowed to take your changes at all, sorry.

> ---
>  drivers/usb/typec/mux/intel_pmc_mux.c | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/mux/intel_pmc_mux.c b/drivers/usb/typec/mux/intel_pmc_mux.c
> index d238913e996a..4bf84466d1ff 100644
> --- a/drivers/usb/typec/mux/intel_pmc_mux.c
> +++ b/drivers/usb/typec/mux/intel_pmc_mux.c
> @@ -432,6 +432,25 @@ static int pmc_usb_connect(struct pmc_usb_port *port, enum usb_role role)
>  	return pmc_usb_command(port, msg, sizeof(msg));
>  }
>  
> +static bool
> +pmc_usb_mux_allow_to_enter_safe_mode(struct pmc_usb_port *port,
> +				      struct typec_mux_state *state)
> +{
> +	if ((IOM_PORT_ACTIVITY_IS(port->iom_status, DP) ||
> +	     IOM_PORT_ACTIVITY_IS(port->iom_status, DP_MFD)) &&
> +	     state->alt &&
> +	     state->alt->svid == USB_TYPEC_DP_SID)
> +		return false;
> +
> +	if ((IOM_PORT_ACTIVITY_IS(port->iom_status, TBT) ||
> +	     IOM_PORT_ACTIVITY_IS(port->iom_status, ALT_MODE_TBT_USB)) &&
> +	     state->alt &&
> +	     state->alt->svid == USB_TYPEC_TBT_SID)
> +		return false;
> +
> +	return true;

Return normal 0/-ERROR for functions like this, don't mess with bool for
a return value, that's just confusing to everyone involved.

thanks,

greg k-h