linux-kernel - Re: [PATCH 1/3] usb: typec: ps883x: Cache register settings, not Type-C mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aPYERtFRKx6jdh_R@kuha.fi.intel.com>
Date: Mon, 20 Oct 2025 12:43:34 +0300
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Konrad Dybcio <konradybcio@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
	Bjorn Andersson <bjorn.andersson@....qualcomm.com>,
	Wesley Cheng <wesley.cheng@....qualcomm.com>,
	Jack Pham <jack.pham@....qualcomm.com>,
	Raghavendra Thoorpu <rthoorpu@....qualcomm.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: Re: [PATCH 1/3] usb: typec: ps883x: Cache register settings, not
 Type-C mode

On Tue, Oct 14, 2025 at 06:06:45PM +0200, Konrad Dybcio wrote:
> From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
> 
> Certain Type-C mode configurations may result in identical settings of
> the PS8830. Check if the latter have changed instead of assuming
> there's always a difference.
> 
> ps883x_set() is changed to accept a typec_retimer_state in preparation
> for more work and the ps883x_sw_set() (which only handles orientation
> switching) is changed to use regmap_assign_bits(), which itself does
> not perform any writes if the desired value is already set.
> 
> Reviewed-by: Jack Pham <jack.pham@....qualcomm.com>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>

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

> ---
>  drivers/usb/typec/mux/ps883x.c | 41 ++++++++++++++++++++++-------------------
>  1 file changed, 22 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/usb/typec/mux/ps883x.c b/drivers/usb/typec/mux/ps883x.c
> index ad59babf7cce..68f172df7be3 100644
> --- a/drivers/usb/typec/mux/ps883x.c
> +++ b/drivers/usb/typec/mux/ps883x.c
> @@ -54,8 +54,9 @@ struct ps883x_retimer {
>  	struct mutex lock; /* protect non-concurrent retimer & switch */
>  
>  	enum typec_orientation orientation;
> -	unsigned long mode;
> -	unsigned int svid;
> +	u8 cfg0;
> +	u8 cfg1;
> +	u8 cfg2;
>  };
>  
>  static int ps883x_configure(struct ps883x_retimer *retimer, int cfg0,
> @@ -64,6 +65,9 @@ static int ps883x_configure(struct ps883x_retimer *retimer, int cfg0,
>  	struct device *dev = &retimer->client->dev;
>  	int ret;
>  
> +	if (retimer->cfg0 == cfg0 && retimer->cfg1 == cfg1 && retimer->cfg2 == cfg2)
> +		return 0;
> +
>  	ret = regmap_write(retimer->regmap, REG_USB_PORT_CONN_STATUS_0, cfg0);
>  	if (ret) {
>  		dev_err(dev, "failed to write conn_status_0: %d\n", ret);
> @@ -82,27 +86,31 @@ static int ps883x_configure(struct ps883x_retimer *retimer, int cfg0,
>  		return ret;
>  	}
>  
> +	retimer->cfg0 = cfg0;
> +	retimer->cfg1 = cfg1;
> +	retimer->cfg2 = cfg2;
> +
>  	return 0;
>  }
>  
> -static int ps883x_set(struct ps883x_retimer *retimer)
> +static int ps883x_set(struct ps883x_retimer *retimer, struct typec_retimer_state *state)
>  {
>  	int cfg0 = CONN_STATUS_0_CONNECTION_PRESENT;
>  	int cfg1 = 0x00;
>  	int cfg2 = 0x00;
>  
>  	if (retimer->orientation == TYPEC_ORIENTATION_NONE ||
> -	    retimer->mode == TYPEC_STATE_SAFE) {
> +	    state->mode == TYPEC_STATE_SAFE) {
>  		return ps883x_configure(retimer, cfg0, cfg1, cfg2);
>  	}
>  
> -	if (retimer->mode != TYPEC_STATE_USB && retimer->svid != USB_TYPEC_DP_SID)
> +	if (state->alt && state->alt->svid != USB_TYPEC_DP_SID)
>  		return -EINVAL;
>  
>  	if (retimer->orientation == TYPEC_ORIENTATION_REVERSE)
>  		cfg0 |= CONN_STATUS_0_ORIENTATION_REVERSED;
>  
> -	switch (retimer->mode) {
> +	switch (state->mode) {
>  	case TYPEC_STATE_USB:
>  		cfg0 |= CONN_STATUS_0_USB_3_1_CONNECTED;
>  		break;
> @@ -149,7 +157,13 @@ static int ps883x_sw_set(struct typec_switch_dev *sw,
>  	if (retimer->orientation != orientation) {
>  		retimer->orientation = orientation;
>  
> -		ret = ps883x_set(retimer);
> +		ret = regmap_assign_bits(retimer->regmap, REG_USB_PORT_CONN_STATUS_0,
> +					 CONN_STATUS_0_ORIENTATION_REVERSED,
> +					 orientation == TYPEC_ORIENTATION_REVERSE);
> +		if (ret) {
> +			dev_err(&retimer->client->dev, "failed to set orientation: %d\n", ret);
> +			return ret;
> +		}
>  	}
>  
>  	mutex_unlock(&retimer->lock);
> @@ -165,18 +179,7 @@ static int ps883x_retimer_set(struct typec_retimer *rtmr,
>  	int ret = 0;
>  
>  	mutex_lock(&retimer->lock);
> -
> -	if (state->mode != retimer->mode) {
> -		retimer->mode = state->mode;
> -
> -		if (state->alt)
> -			retimer->svid = state->alt->svid;
> -		else
> -			retimer->svid = 0;
> -
> -		ret = ps883x_set(retimer);
> -	}
> -
> +	ret = ps883x_set(retimer, state);
>  	mutex_unlock(&retimer->lock);
>  
>  	if (ret)
> 
> -- 
> 2.51.0

-- 
heikki