linux-kernel - Re: [PATCH v4 1/1] usb: typec: intel_pmc_mux: Configure cable generation value for USB4

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Date:   Thu, 10 Dec 2020 13:50:59 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Utkarsh Patel <utkarsh.h.patel@...el.com>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        pmalani@...omium.org, enric.balletbo@...labora.com,
        rajmohan.mani@...el.com, azhar.shaikh@...el.com
Subject: Re: [PATCH v4 1/1] usb: typec: intel_pmc_mux: Configure cable
 generation value for USB4

On Tue, Dec 08, 2020 at 08:24:08PM -0800, Utkarsh Patel wrote:
> USB4 specification chapter 3 indicates that cable data rates have to be
> rounded for USB4 device to operate as USB4.
> With that configure cable generation value to use rounded data rates for
> USB4.
> 
> Signed-off-by: Utkarsh Patel <utkarsh.h.patel@...el.com>

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

> ---
> Changes in v4:
> - Removed usage of tbt_mode_vdo since data rates should always be rounded
>   in the case of USB4.
> - Updated commit message to reflect the change.
> 
> Changes in v3:
> - Moved TBT_CABLE_ROUNDED_SUPPORT assignment to the same line.
> 
> Changes in v2:
> - No change.
> ---
>  drivers/usb/typec/mux/intel_pmc_mux.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/usb/typec/mux/intel_pmc_mux.c b/drivers/usb/typec/mux/intel_pmc_mux.c
> index e58ae8a7fefb..cf37a59ce130 100644
> --- a/drivers/usb/typec/mux/intel_pmc_mux.c
> +++ b/drivers/usb/typec/mux/intel_pmc_mux.c
> @@ -327,6 +327,11 @@ pmc_usb_mux_usb4(struct pmc_usb_port *port, struct typec_mux_state *state)
>  		fallthrough;
>  	default:
>  		req.mode_data |= PMC_USB_ALTMODE_ACTIVE_CABLE;
> +
> +		/* Configure data rate to rounded in the case of Active TBT3
> +		 * and USB4 cables.
> +		 */
> +		req.mode_data |= PMC_USB_ALTMODE_TBT_GEN(1);
>  		break;
>  	}
>  
> -- 
> 2.17.1

-- 
heikki