linux-kernel - Re: [PATCH v1 1/1] usb: typec: ucsi: Check capabilities before cable and identity discovery

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Message-ID: <ZfOTHO6FMlpjeQhZ@google.com>
Date: Fri, 15 Mar 2024 00:15:24 +0000
From: Benson Leung <bleung@...gle.com>
To: Jameson Thies <jthies@...gle.com>
Cc: heikki.krogerus@...ux.intel.com, linux-usb@...r.kernel.org,
	pmalani@...omium.org, abhishekpandit@...omium.org,
	andersson@...nel.org, dmitry.baryshkov@...aro.org,
	fabrice.gasnier@...s.st.com, gregkh@...uxfoundation.org,
	hdegoede@...hat.com, neil.armstrong@...aro.org,
	rajaram.regupathy@...el.com, saranya.gopal@...el.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] usb: typec: ucsi: Check capabilities before cable
 and identity discovery

Hi Jameson,

On Thu, Mar 14, 2024 at 11:55:54PM +0000, Jameson Thies wrote:
> Check the UCSI_CAP_GET_PD_MESSAGE bit before sending GET_PD_MESSAGE to
> discover partner and cable identity, check UCSI_CAP_CABLE_DETAILS before
> sending GET_CABLE_PROPERTY to discover the cable and check
> UCSI_CAP_ALT_MODE_DETAILS before registering the a cable plug.
> 
> Suggested-by: Neil Armstrong <neil.armstrong@...aro.org>
> Signed-off-by: Jameson Thies <jthies@...gle.com>

Since Neil pointed out that this error appeared starting in 38ca416597b0,
I think it would be appropriate to tag this commit with a Fixes: tag.

See here on instructions how to describe a Fixes:
https://www.kernel.org/doc/html/v4.10/process/submitting-patches.html#describe-changes


> ---
> Confirmed a device which supports GET_PD_MESSAGE, GET_CABLE_PROPERTY and
> GET_ALTERNATE_MODES still requested identity and cable information.
> 
> This moves 8 bits from "reserved_1" to "features" in the ucsi_capability
> struct. Really, this should be 24 bits to reflect the field size in UCSI.
> But, as of UCSI 3.0, this will not overflow becasue the bmOptionalFeatures
> description only defines 14 bits.

Are you sure you wanted to include this information below the --- ? This won't
be incorporated into the commit message when this is merged.


Thanks,
Benson

> 
>  drivers/usb/typec/ucsi/ucsi.c | 34 +++++++++++++++++++++-------------
>  drivers/usb/typec/ucsi/ucsi.h |  5 +++--
>  2 files changed, 24 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index cf52cb34d2859..958dc82989b60 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -1133,17 +1133,21 @@ static int ucsi_check_cable(struct ucsi_connector *con)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = ucsi_get_cable_identity(con);
> -	if (ret < 0)
> -		return ret;
> +	if (con->ucsi->cap.features & UCSI_CAP_GET_PD_MESSAGE) {
> +		ret = ucsi_get_cable_identity(con);
> +		if (ret < 0)
> +			return ret;
> +	}
>  
> -	ret = ucsi_register_plug(con);
> -	if (ret < 0)
> -		return ret;
> +	if (con->ucsi->cap.features & UCSI_CAP_ALT_MODE_DETAILS) {
> +		ret = ucsi_register_plug(con);
> +		if (ret < 0)
> +			return ret;
>  
> -	ret = ucsi_register_altmodes(con, UCSI_RECIPIENT_SOP_P);
> -	if (ret < 0)
> -		return ret;
> +		ret = ucsi_register_altmodes(con, UCSI_RECIPIENT_SOP_P);
> +		if (ret < 0)
> +			return ret;
> +	}
>  
>  	return 0;
>  }
> @@ -1189,8 +1193,10 @@ static void ucsi_handle_connector_change(struct work_struct *work)
>  			ucsi_register_partner(con);
>  			ucsi_partner_task(con, ucsi_check_connection, 1, HZ);
>  			ucsi_partner_task(con, ucsi_check_connector_capability, 1, HZ);
> -			ucsi_partner_task(con, ucsi_get_partner_identity, 1, HZ);
> -			ucsi_partner_task(con, ucsi_check_cable, 1, HZ);
> +			if (con->ucsi->cap.features & UCSI_CAP_GET_PD_MESSAGE)
> +				ucsi_partner_task(con, ucsi_get_partner_identity, 1, HZ);
> +			if (con->ucsi->cap.features & UCSI_CAP_CABLE_DETAILS)
> +				ucsi_partner_task(con, ucsi_check_cable, 1, HZ);
>  
>  			if (UCSI_CONSTAT_PWR_OPMODE(con->status.flags) ==
>  			    UCSI_CONSTAT_PWR_OPMODE_PD)
> @@ -1589,8 +1595,10 @@ static int ucsi_register_port(struct ucsi *ucsi, struct ucsi_connector *con)
>  		ucsi_register_partner(con);
>  		ucsi_pwr_opmode_change(con);
>  		ucsi_port_psy_changed(con);
> -		ucsi_get_partner_identity(con);
> -		ucsi_check_cable(con);
> +		if (con->ucsi->cap.features & UCSI_CAP_GET_PD_MESSAGE)
> +			ucsi_get_partner_identity(con);
> +		if (con->ucsi->cap.features & UCSI_CAP_CABLE_DETAILS)
> +			ucsi_check_cable(con);
>  	}
>  
>  	/* Only notify USB controller if partner supports USB data */
> diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
> index 32daf5f586505..0e7c92eb1b227 100644
> --- a/drivers/usb/typec/ucsi/ucsi.h
> +++ b/drivers/usb/typec/ucsi/ucsi.h
> @@ -206,7 +206,7 @@ struct ucsi_capability {
>  #define UCSI_CAP_ATTR_POWER_OTHER		BIT(10)
>  #define UCSI_CAP_ATTR_POWER_VBUS		BIT(14)
>  	u8 num_connectors;
> -	u8 features;
> +	u16 features;
>  #define UCSI_CAP_SET_UOM			BIT(0)
>  #define UCSI_CAP_SET_PDM			BIT(1)
>  #define UCSI_CAP_ALT_MODE_DETAILS		BIT(2)
> @@ -215,7 +215,8 @@ struct ucsi_capability {
>  #define UCSI_CAP_CABLE_DETAILS			BIT(5)
>  #define UCSI_CAP_EXT_SUPPLY_NOTIFICATIONS	BIT(6)
>  #define UCSI_CAP_PD_RESET			BIT(7)
> -	u16 reserved_1;
> +#define UCSI_CAP_GET_PD_MESSAGE		BIT(8)
> +	u8 reserved_1;
>  	u8 num_alt_modes;
>  	u8 reserved_2;
>  	u16 bc_version;
> -- 
> 2.44.0.291.gc1ea87d7ee-goog
> 

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