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d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/zGvD23D7UzPmkeJaICeLLr5BBiyIFomvZLFOZzlxm4=; b=sWZbptmGyS0HPorNQPHEBCpGT7PWD1PZ2YKUlV704TIbMKf0omwrJYNl9x1MggZZGS 3GC0IeLVmzgVRQ+swjXDkGwHoKyHVYFZBeKA8hH+6dX+jfKRDHYKXCa9fYE261x8sWZd BwGl5kY150JkX7hYFtM+6K0u0WzEg2JKt4Xu5xu8WJ4+Iuj6eBtbuIZjLYny9WQosJn+ QMep6Nb1xb26cR5rFo4uIYqSfb7FG1ipIAnIfikSpMTHBkMiBwrmRNHi6vub9c2Sj4Ro K8Bre5HXAv/H9dG4wxPiHOBGBhZl3ziMEbpHGzJa8kZ5z3v3eLuNjk0RGk7twMcfGh9T 34Ag== X-Gm-Message-State: AOAM531lFX9Lrzq20BmqlJzZ2zYNAIt7FeRjLy52Ltl1uQMqbvkbDTjC iEdcsZPb+IcUBMe7HZiDdezU7lhjsfF/EL+qpH7ENg== X-Google-Smtp-Source: ABdhPJzjhP/CSxgRJgE+YlE4odaKeOT22nWwH6kRTVVzdqJFbEKMz324CiWy7zrV6wEReKB3J/v4H0DoOJs0nApprAA= X-Received: by 2002:a37:6195:: with SMTP id v143mr13545153qkb.71.1605842043665; Thu, 19 Nov 2020 19:14:03 -0800 (PST) MIME-Version: 1.0 References: <20201119063211.2264-1-utkarsh.h.patel@intel.com> <20201119063211.2264-3-utkarsh.h.patel@intel.com> <20201119080906.GE3652649@google.com> In-Reply-To: From: Prashant Malani Date: Thu, 19 Nov 2020 19:13:51 -0800 Message-ID: Subject: Re: [PATCH v3 2/4] platform/chrome: cros_ec_typec: Use Thunderbolt 3 cable discover mode VDO in USB4 mode To: "Patel, Utkarsh H" Cc: "linux-kernel@vger.kernel.org" , "linux-usb@vger.kernel.org" , "heikki.krogerus@linux.intel.com" , "enric.balletbo@collabora.com" , "Mani, Rajmohan" , "Shaikh, Azhar" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Utkarsh, On Thu, Nov 19, 2020 at 6:32 PM Patel, Utkarsh H wrote: > > Hi Prashant, > > > -----Original Message----- > > From: Prashant Malani > > Sent: Thursday, November 19, 2020 12:09 AM > > To: Patel, Utkarsh H > > Cc: linux-kernel@vger.kernel.org; linux-usb@vger.kernel.org; > > heikki.krogerus@linux.intel.com; enric.balletbo@collabora.com; Mani, > > Rajmohan ; Shaikh, Azhar > > > > Subject: Re: [PATCH v3 2/4] platform/chrome: cros_ec_typec: Use Thunderbolt > > 3 cable discover mode VDO in USB4 mode > > > > Hi Utkarsh, > > > > On Wed, Nov 18, 2020 at 10:32:09PM -0800, Utkarsh Patel wrote: > > > Configure Thunderbolt 3 cable generation value by filling Thunderbolt > > > 3 cable discover mode VDO to support rounded Thunderbolt 3 cables. > > > While we are here use Thunderbolt 3 cable discover mode VDO to fill > > > active cable plug link training value. > > > > > > Suggested-by: Heikki Krogerus > > > Signed-off-by: Utkarsh Patel > > > > > > -- > > > Changes in v3: > > > - Added a check for cable's TBT support before filling TBT3 discover mode > > > VDO. > > > > > > Changes in v2: > > > - No change. > > > -- > > > --- > > > drivers/platform/chrome/cros_ec_typec.c | 14 ++++++++++++-- > > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/platform/chrome/cros_ec_typec.c > > > b/drivers/platform/chrome/cros_ec_typec.c > > > index 8111ed1fc574..68b17ee1d1ae 100644 > > > --- a/drivers/platform/chrome/cros_ec_typec.c > > > +++ b/drivers/platform/chrome/cros_ec_typec.c > > > @@ -514,8 +514,18 @@ static int cros_typec_enable_usb4(struct > > cros_typec_data *typec, > > > else if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_CABLE) > > > data.eudo |= EUDO_CABLE_TYPE_RE_TIMER << > > EUDO_CABLE_TYPE_SHIFT; > > > > > > - data.active_link_training = !!(pd_ctrl->control_flags & > > > - USB_PD_CTRL_ACTIVE_LINK_UNIDIR); > > > + /* > > > + * Filling TBT3 Cable VDO when TBT3 cable is being used to establish > > > + * USB4 connection. > > > + */ > > > + if (pd_ctrl->cable_gen) { > > > + data.tbt_cable_vdo = TBT_MODE; > > > + > > > + if (pd_ctrl->control_flags & > > USB_PD_CTRL_ACTIVE_LINK_UNIDIR) > > > + data.tbt_cable_vdo |= TBT_CABLE_LINK_TRAINING; > > > + > > > + data.tbt_cable_vdo |= TBT_SET_CABLE_ROUNDED(pd_ctrl- > > >cable_gen); > > > + } > > > > I think the following would decouple Rounded Support and Active Cable Link > > Training?: > > Any reason you would want to decouple them? Is there anything in the spec that says Active Cable Link Training needs Rounded Cable support (or vice versa)? If yes, could you kindly point me to the relevant portion in the spec that states this? If no, then the two should be set independently based on the response from the Chrome EC. FWIW, Table F-11 ( TBT3 Cable Discover Mode VDO Responses) from the USB Type-C Cable & Connector Spec (Rel 2.0) suggests the two are independent bits although I don't have access to the TBT3 spec to confirm. BR, -Prashant