linux-kernel - RE: [PATCH v2 4/5] platform/chrome: cros_ec_typec: Add Displayport Alternatemode 2.1 Support

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Date:   Fri, 8 Sep 2023 20:11:27 +0000
From:   "Patel, Utkarsh H" <utkarsh.h.patel@...el.com>
To:     Prashant Malani <pmalani@...omium.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "heikki.krogerus@...ux.intel.com" <heikki.krogerus@...ux.intel.com>,
        "chrome-platform@...ts.linux.dev" <chrome-platform@...ts.linux.dev>,
        "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        "bleung@...omium.org" <bleung@...omium.org>
Subject: RE: [PATCH v2 4/5] platform/chrome: cros_ec_typec: Add Displayport
 Alternatemode 2.1 Support

Hi Prashant,

Thank you for the review and feedback.

> -----Original Message-----
> From: Prashant Malani <pmalani@...omium.org>
> Sent: Friday, September 8, 2023 10:03 AM
> To: Patel, Utkarsh H <utkarsh.h.patel@...el.com>
> Cc: linux-kernel@...r.kernel.org; linux-usb@...r.kernel.org;
> heikki.krogerus@...ux.intel.com; chrome-platform@...ts.linux.dev;
> andriy.shevchenko@...ux.intel.com; bleung@...omium.org
> Subject: Re: [PATCH v2 4/5] platform/chrome: cros_ec_typec: Add Displayport
> Alternatemode 2.1 Support
> 
> Hi Utkarsh,
> 
> Just a minor thing you can fix for the next version (since it looks like there will
> be one).
> 
> On Aug 31 15:24, Patel, Utkarsh H wrote:
> > Hello,
> >
> > >  drivers/platform/chrome/cros_ec_typec.c | 31
> > > +++++++++++++++++++++++++
> > >  1 file changed, 31 insertions(+)
> > >
> > > diff --git a/drivers/platform/chrome/cros_ec_typec.c
> > > b/drivers/platform/chrome/cros_ec_typec.c
> > > index d0b4d3fc40ed..8372f13052a8 100644
> > > --- a/drivers/platform/chrome/cros_ec_typec.c
> > > +++ b/drivers/platform/chrome/cros_ec_typec.c
> > > @@ -492,6 +492,8 @@ static int cros_typec_enable_dp(struct
> > > cros_typec_data *typec,  {
> > >  	struct cros_typec_port *port = typec->ports[port_num];
> > >  	struct typec_displayport_data dp_data;
> > > +	u32 cable_tbt_vdo;
> > > +	u32 cable_dp_vdo;
> > >  	int ret;
> > >
> > >  	if (typec->pd_ctrl_ver < 2) {
> > > @@ -524,6 +526,35 @@ static int cros_typec_enable_dp(struct
> > > cros_typec_data *typec,
> > >  	port->state.data = &dp_data;
> > >  	port->state.mode = TYPEC_MODAL_STATE(ffs(pd_ctrl->dp_mode));
> > >
> > > +	/* Get cable VDO for cables with DPSID to check DPAM2.1 is
> > > supported */
> > > +	cable_dp_vdo = cros_typec_get_cable_vdo(port,
> > > USB_TYPEC_DP_SID);
> > > +
> > > +	/**
> > > +	 * Get cable VDO for thunderbolt cables and cables with DPSID but
> > > does not
> > > +	 * support DPAM2.1.
> > > +	 */
> > > +	cable_tbt_vdo = cros_typec_get_cable_vdo(port,
> > > USB_TYPEC_TBT_SID);
> > > +
> > > +	if (cable_dp_vdo & DP_CAP_DPAM_VERSION) {
> > > +		dp_data.conf |= cable_dp_vdo;
> > > +	} else if (cable_tbt_vdo) {
> > > +		u8 cable_speed = TBT_CABLE_SPEED(cable_tbt_vdo);
> Can we declare this variable at the top? That is the style in this file and quite
> commonly seen elsewhere.
> 
> Or better yet, just inline this and get rid of the extra variable altogether:
> 
> 	dp_data.conf |= TBT_CABLE_SPEED(...) <<
> DP_CONF_SIGNALLING_SHIFT;

Ack.

> 
> > > +
> > > +		dp_data.conf |= cable_speed <<
> > > DP_CONF_SIGNALLING_SHIFT;
> > > +
> > > +		/* Cable Type */
> > > +		if (cable_tbt_vdo & TBT_CABLE_OPTICAL)
> > > +			dp_data.conf |= DP_CONF_CABLE_TYPE_OPTICAL <<
> > > DP_CONF_CABLE_TYPE_SHIFT;
> > > +		else if (cable_tbt_vdo & TBT_CABLE_RETIMER)
> > > +			dp_data.conf |= DP_CONF_CABLE_TYPE_RE_TIMER <<
> > > DP_CONF_CABLE_TYPE_SHIFT;
> > > +		else if (cable_tbt_vdo & TBT_CABLE_ACTIVE_PASSIVE)
> > > +			dp_data.conf |= DP_CONF_CABLE_TYPE_RE_DRIVER
> > > << DP_CONF_CABLE_TYPE_SHIFT;
> > > +	} else if (PD_IDH_PTYPE(port->c_identity.id_header) ==
> > > IDH_PTYPE_PCABLE) {
> > > +		u8 cable_speed = VDO_CABLE_SPEED(port-
> > > >c_identity.vdo[0]);
> Same here, you can inline this without affecting readability too much.

Ack.

Sincerely,
Utkarsh Patel.