linux-kernel - Re: [PATCH v2 5/6] usb: pd: Add captive Type C cable type

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Message-ID: <20201106185249.GA2874493@google.com>
Date:   Fri, 6 Nov 2020 10:52:49 -0800
From:   Benson Leung <bleung@...gle.com>
To:     Prashant Malani <pmalani@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        gregkh@...uxfoundation.org,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: Re: [PATCH v2 5/6] usb: pd: Add captive Type C cable type

Hi Prashant,


On Fri, Nov 06, 2020 at 10:41:08AM -0800, Prashant Malani wrote:
> The USB Power Delivery Specification R3.0 adds a captive cable type
> to the "USB Type-C plug to USB Type-C/Captive" field (Bits 19-18,
> Passive/Active Cable VDO, Table 6-38 & 6-39).
> 
> Add the corresponding definition to the Cable VDO header. Also add a
> helper macro to get the Type C cable connector type, when provided
> the cable VDO.
> 
> Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Signed-off-by: Prashant Malani <pmalani@...omium.org>

Reviewed-by: Benson Leung <bleung@...omium.org>

Looks good, to modify the Cable VDO decoding to bring it up to date to PD 3.0.

I should also note that the ID Header VDO also has a new field (that I added to
the PD spec) that marks whether or not SOP/SOP' is a captive plug versus a
receptacle as well. Nothing depends on it yet, but we should keep this in
mind for future changes to the connector class.

Thanks,
Benson

> ---
> 
> Changes in v2:
> - No changes.
> 
>  include/linux/usb/pd_vdo.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/usb/pd_vdo.h b/include/linux/usb/pd_vdo.h
> index 68bdc4e2f5a9..8c5cb5830754 100644
> --- a/include/linux/usb/pd_vdo.h
> +++ b/include/linux/usb/pd_vdo.h
> @@ -177,7 +177,7 @@
>   * <31:28> :: Cable HW version
>   * <27:24> :: Cable FW version
>   * <23:20> :: Reserved, Shall be set to zero
> - * <19:18> :: type-C to Type-A/B/C (00b == A, 01 == B, 10 == C)
> + * <19:18> :: type-C to Type-A/B/C/Captive (00b == A, 01 == B, 10 == C, 11 == Captive)
>   * <17>    :: Type-C to Plug/Receptacle (0b == plug, 1b == receptacle)
>   * <16:13> :: cable latency (0001 == <10ns(~1m length))
>   * <12:11> :: cable termination type (11b == both ends active VCONN req)
> @@ -193,6 +193,7 @@
>  #define CABLE_ATYPE		0
>  #define CABLE_BTYPE		1
>  #define CABLE_CTYPE		2
> +#define CABLE_CAPTIVE		3
>  #define CABLE_PLUG		0
>  #define CABLE_RECEPTACLE	1
>  #define CABLE_CURR_1A5		0
> @@ -208,6 +209,7 @@
>  	 | (tx1d) << 10 | (tx2d) << 9 | (rx1d) << 8 | (rx2d) << 7	\
>  	 | ((cur) & 0x3) << 5 | (vps) << 4 | (sopp) << 3		\
>  	 | ((usbss) & 0x7))
> +#define VDO_TYPEC_CABLE_TYPE(vdo)	(((vdo) >> 18) & 0x3)
>  
>  /*
>   * AMA VDO
> -- 
> 2.29.1.341.ge80a0c044ae-goog
> 

-- 
Benson Leung
Staff Software Engineer
Chrome OS Kernel
Google Inc.
bleung@...gle.com
Chromium OS Project
bleung@...omium.org

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