Re: [PATCH] usb: typec: tcpm: Fix altmode re-registration causes sysfs create fail

[Macpaul Lin <macpaul.lin@mediatek.com>]

On 12/15/22 17:21, cy_huang wrote:
> From: ChiYuan Huang <cy_huang@richtek.com>
> 
> There's the altmode re-registeration issue after data role
> swap (DR_SWAP).
> 
> Comparing to USBPD 2.0, in USBPD 3.0, it loose the limit that only DFP
> can initiate the VDM command to get partner identity information.
> 
> For a USBPD 3.0 UFP device, it may already get the identity information
> from its port partner before DR_SWAP. If DR_SWAP send or receive at the
> mean time, 'send_discover' flag will be raised again. It causes discover
> identify action restart while entering ready state. And after all
> discover actions are done, the 'tcpm_register_altmodes' will be called.
> If old altmode is not unregistered, this sysfs create fail can be found.
> 
> In 'DR_SWAP_CHANGE_DR' state case, only DFP will unregister altmodes.
> For UFP, the original altmodes keep registered.
> 
> This patch fix the logic that after DR_SWAP, 'tcpm_unregister_altmodes'
> must be called whatever the current data role is.
> 
> Fixes: ae8a2ca8a221 ("usb: typec: Group all TCPCI/TCPM code together)
> Reported-by: TommyYl Chen <tommyyl.chen@mediatek.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> ---
> Hi,
> 
> Below's the issue log for the reference.
> 
> *TCPM
> [    3.856679] AMS DISCOVER_MODES start
> [    3.856687] PD TX, header: 0x188f
> [    3.858827] PD TX complete, status: 0
> [    3.865330] PD RX, header: 0x2daf [1]
> [    3.865340] Rx VDM cmd 0xff01a043 type 1 cmd 3 len 2
> [    3.865348] AMS DISCOVER_MODES finished
> [    3.865352]  Alternate mode 0: SVID 0xff01, VDO 1: 0x001c0045
> [    3.865362] AMS DISCOVER_MODES start
> [    3.865367] PD TX, header: 0x1a8f
> [    3.867802] PD TX complete, status: 0
> [    3.875208] PD RX, header: 0x2faf [1]
> [    3.875216] Rx VDM cmd 0x413ca043 type 1 cmd 3 len 2
> [    3.875222] AMS DISCOVER_MODES finished
> [    3.875225]  Alternate mode 1: SVID 0x413c, VDO 1: 0x00000001
> [    3.938243] AMS GET_SINK_CAPABILITIES start
> [    3.938255] state change SNK_READY -> AMS_START [rev3 GET_SINK_CAPABILITIES]
> [    3.938266] state change AMS_START -> GET_SINK_CAP [rev3 GET_SINK_CAPABILITIES]
> [    3.938274] PD TX, header: 0xe88
> [    3.940268] PD TX complete, status: 0
> [    3.940310] pending state change GET_SINK_CAP -> GET_SINK_CAP_TIMEOUT @ 60 ms
> [rev3 GET_SINK_CAPABILITIES]
> [    3.946291] PD RX, header: 0x13a4 [1]
> [    3.946295] Port partner FRS capable partner_frs_current:0 port_frs_current:0 enable:n
> [    3.946298] state change GET_SINK_CAP -> SNK_READY [rev3 GET_SINK_CAPABILITIES]
> [    3.946304] AMS GET_SINK_CAPABILITIES finished
> [    4.239342] CC1: 5 -> 4, CC2: 0 -> 0 [state SNK_READY, polarity 0, connected]
> [    4.256594] PD RX, header: 0x5a9 [1]
> [    4.256603] state change SNK_READY -> DR_SWAP_ACCEPT [rev3 DATA_ROLE_SWAP]
> [    4.256609] PD TX, header: 0x83
> [    4.258528] PD TX complete, status: 0
> [    4.258584] state change DR_SWAP_ACCEPT -> DR_SWAP_CHANGE_DR [rev3 DATA_ROLE_SWAP]
> [    4.258591] Requesting mux state 1, usb-role 1, orientation 1
> [    4.259588] AMS DATA_ROLE_SWAP finished
> [    4.259592] state change DR_SWAP_CHANGE_DR -> SNK_READY [rev3 NONE_AMS]
> [    4.259605] AMS DISCOVER_IDENTITY start
> [    4.259609] Sink TX No Go
> [    4.260874] CC1: 4 -> 5, CC2: 0 -> 0 [state SNK_READY, polarity 0, connected]
> [    4.359636] AMS DISCOVER_IDENTITY start
> [    4.359642] PD TX, header: 0x12af
> [    4.361884] PD TX complete, status: 0
> [    4.369433] PD RX, header: 0x578f [1]
> [    4.369439] Rx VDM cmd 0xff00a041 type 1 cmd 1 len 5
> [    4.369448] AMS DISCOVER_IDENTITY finished
> [    4.369515] Identity: 413c:c013.0712
> [    4.369521] AMS DISCOVER_SVIDS start
> [    4.369524] PD TX, header: 0x14af
> [    4.371696] PD TX complete, status: 0
> [    4.378564] PD RX, header: 0x398f [1]
> [    4.378573] Rx VDM cmd 0xff00a042 type 1 cmd 2 len 3
> [    4.378579] AMS DISCOVER_SVIDS finished
> [    4.378582] SVID 1: 0xff01
> [    4.378584] SVID 2: 0x413c
> [    4.378594] AMS DISCOVER_MODES start
> [    4.378597] PD TX, header: 0x16af
> [    4.380696] PD TX complete, status: 0
> [    4.387008] PD RX, header: 0x2b8f [1]
> [    4.387014] Rx VDM cmd 0xff01a043 type 1 cmd 3 len 2
> [    4.387021] AMS DISCOVER_MODES finished
> [    4.387023]  Alternate mode 0: SVID 0xff01, VDO 1: 0x001c0045
> [    4.387029] AMS DISCOVER_MODES start
> [    4.387031] PD TX, header: 0x18af
> [    4.389134] PD TX complete, status: 0
> [    4.395528] PD RX, header: 0x2d8f [1]
> [    4.395538] Rx VDM cmd 0x413ca043 type 1 cmd 3 len 2
> [    4.395546] AMS DISCOVER_MODES finished
> [    4.395548]  Alternate mode 1: SVID 0x413c, VDO 1: 0x00000001
> 
> *Kernel TRACE
> sysfs: cannot create duplicate filename
> '/devices/platform/soc/11d01000.i2c/i2c-0/0-0034/mt6360-tcpc.6.auto/typec/port0/port0.0/partner'
> CPU: 2 PID: 299 Comm: mt6360-tcpc.6.a Tainted: GO      5.15.37-mtk+g880abc5122e7 #1
> Hardware name: MediaTek MT8195 demo board (DT)
> Call trace:
>   dump_backtrace+0x0/0x1ac
>   show_stack+0x24/0x30
>   dump_stack_lvl+0x68/0x84
>   dump_stack+0x1c/0x38
>   sysfs_warn_dup+0x70/0x90
>   typec_probe+0xa4/0x134 [typec]
>   really_probe.part.0+0xa4/0x310
>   __device_attach_driver+0x100/0x16c
>   bus_for_each_drv+0x84/0xe0
>   __device_attach+0xe0/0x1ac
>   device_add+0x39c/0x8b0
>   device_register+0x2c/0x40
>   typec_register_altmode+0x1f4/0x360 [typec]
>   typec_partner_register_altmode+0x1c/0x30 [typec]
>   tcpm_pd_rx_handler+0x19d4/0x1c0c [tcpm]
>   kthread_worker_fn+0xb8/0x290
>   kthread+0x15c/0x170
>   ret_from_fork+0x10/0x20
> [    4.395962] typec_displayport port0-partner.2: failed to create symlinks
> [    4.395967] typec_displayport: probe of port0-partner.2 failed with error -17
> 
> It seems it's a common issue if typec port supports the modal operation.
> 
> ---
>   drivers/usb/typec/tcpm/tcpm.c | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 904c7b4..59b366b 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4594,14 +4594,13 @@ static void run_state_machine(struct tcpm_port *port)
>   		tcpm_set_state(port, ready_state(port), 0);
>   		break;
>   	case DR_SWAP_CHANGE_DR:
> -		if (port->data_role == TYPEC_HOST) {
> -			tcpm_unregister_altmodes(port);
> +		tcpm_unregister_altmodes(port);
> +		if (port->data_role == TYPEC_HOST)
>   			tcpm_set_roles(port, true, port->pwr_role,
>   				       TYPEC_DEVICE);
> -		} else {
> +		else
>   			tcpm_set_roles(port, true, port->pwr_role,
>   				       TYPEC_HOST);
> -		}
>   		tcpm_ams_finish(port);
>   		tcpm_set_state(port, ready_state(port), 0);
>   		break;

Reviewed-by: Macpaul Lin <macpaul.lin@mediatek.com>

Thank for your help.

Regards,
Macpaul Lin

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