Re: [PATCH 1/1] usb: typec: displayport: Receive DP Status Update NAK request exit dp altmode

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Sun, Feb 09, 2025 at 03:19:26PM +0800, joswang wrote:
> From: Jos Wang <joswang@lenovo.com>
> 
> Although some Type-C DRD devices that do not support the DP Sink
> function (such as Huawei Mate 40Pro), the Source Port initiates
> Enter Mode CMD, but the device responds to Enter Mode ACK, the
> Source port then initiates DP Status Update CMD, and the device
> responds to DP Status Update NAK.
> 
> As PD2.0 spec ("6.4.4.3.4 Enter Mode Command")，A DR_Swap Message
> Shall Not be sent during Modal Operation between the Port Partners.
> At this time, the source port initiates DR_Swap message through the
> "echo device > /sys/class/typec/port0/data_role" command to switch
> the data role from host to device. The device will initiate a Hard
> Reset for recovery, resulting in the failure of data role swap.
> 
> Therefore, when DP Status Update NAK is received, Exit Mode CMD is
> initiated to exit the currently entered DP altmode.
> 
> Signed-off-by: Jos Wang <joswang@lenovo.com>

This looks okay to me, but Benson, can you take a look at this?

> ---
>  drivers/usb/typec/altmodes/displayport.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
> index ac84a6d64c2f..b09b58d7311d 100644
> --- a/drivers/usb/typec/altmodes/displayport.c
> +++ b/drivers/usb/typec/altmodes/displayport.c
> @@ -393,6 +393,10 @@ static int dp_altmode_vdm(struct typec_altmode *alt,
>  		break;
>  	case CMDT_RSP_NAK:
>  		switch (cmd) {
> +		case DP_CMD_STATUS_UPDATE:
> +			if (typec_altmode_exit(alt))
> +				dev_err(&dp->alt->dev, "Exit Mode Failed!\n");
> +			break;
>  		case DP_CMD_CONFIGURE:
>  			dp->data.conf = 0;
>  			ret = dp_altmode_configured(dp);
> -- 
> 2.17.1

-- 
heikki