Re: [PATCH 09/11] staging: typec: tcpm: typec: tcpm: Wait for CC debounce before PD excg

From: Guenter Roeck
Date: Sun Aug 27 2017 - 13:26:58 EST


On Sat, Aug 26, 2017 at 11:51:27PM -0700, Badhri Jagan Sridharan wrote:
> Once, Rp or Rd is switched, wait for PD_T_CC_DEBOUNCE. If not the
> PS_RDY message transmitted might result in failure.
> Also, Only wait for PD_T_SRCSWAPSTDBY while in
> PR_SWAP_SRC_SNK_TRANSITION_OFF. PD_T_PS_SOURCE_OFF is the overall
> time after which the initial sink would issue hard reset.
>
> Signed-off-by: Badhri Jagan Sridharan <Badhri@xxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

> ---
> drivers/staging/typec/pd.h | 2 ++
> drivers/staging/typec/tcpm.c | 25 ++++++++++++++++++++++---
> 2 files changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/typec/pd.h b/drivers/staging/typec/pd.h
> index 510ef7279900..30b32ad72acd 100644
> --- a/drivers/staging/typec/pd.h
> +++ b/drivers/staging/typec/pd.h
> @@ -278,6 +278,8 @@ static inline unsigned int rdo_max_power(u32 rdo)
> #define PD_T_VCONN_SOURCE_ON 100
> #define PD_T_SINK_REQUEST 100 /* 100 ms minimum */
> #define PD_T_ERROR_RECOVERY 100 /* minimum 25 is insufficient */
> +#define PD_T_SRCSWAPSTDBY 625 /* Maximum of 650ms */
> +#define PD_T_NEWSRC 250 /* Maximum of 275ms */
>
> #define PD_T_DRP_TRY 100 /* 75 - 150 ms */
> #define PD_T_DRP_TRYWAIT 600 /* 400 - 800 ms */
> diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
> index 1f6827f32b29..a7da609006f5 100644
> --- a/drivers/staging/typec/tcpm.c
> +++ b/drivers/staging/typec/tcpm.c
> @@ -90,9 +90,11 @@
> S(PR_SWAP_START), \
> S(PR_SWAP_SRC_SNK_TRANSITION_OFF), \
> S(PR_SWAP_SRC_SNK_SOURCE_OFF), \
> + S(PR_SWAP_SRC_SNK_SOURCE_OFF_CC_DEBOUNCED), \
> S(PR_SWAP_SRC_SNK_SINK_ON), \
> S(PR_SWAP_SNK_SRC_SINK_OFF), \
> S(PR_SWAP_SNK_SRC_SOURCE_ON), \
> + S(PR_SWAP_SNK_SRC_SOURCE_ON_VBUS_RAMPED_UP), \
> \
> S(VCONN_SWAP_ACCEPT), \
> S(VCONN_SWAP_SEND), \
> @@ -1395,7 +1397,7 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
> SNK_TRANSITION_SINK_VBUS, 0);
> }
> break;
> - case PR_SWAP_SRC_SNK_SOURCE_OFF:
> + case PR_SWAP_SRC_SNK_SOURCE_OFF_CC_DEBOUNCED:
> tcpm_set_state(port, PR_SWAP_SRC_SNK_SINK_ON, 0);
> break;
> case PR_SWAP_SNK_SRC_SINK_OFF:
> @@ -2679,11 +2681,17 @@ static void run_state_machine(struct tcpm_port *port)
> case PR_SWAP_SRC_SNK_TRANSITION_OFF:
> tcpm_set_vbus(port, false);
> port->explicit_contract = false;
> + /* allow time for Vbus discharge, must be < tSrcSwapStdby */
> tcpm_set_state(port, PR_SWAP_SRC_SNK_SOURCE_OFF,
> - PD_T_PS_SOURCE_OFF);
> + PD_T_SRCSWAPSTDBY);
> break;
> case PR_SWAP_SRC_SNK_SOURCE_OFF:
> tcpm_set_cc(port, TYPEC_CC_RD);
> + /* allow CC debounce */
> + tcpm_set_state(port, PR_SWAP_SRC_SNK_SOURCE_OFF_CC_DEBOUNCED,
> + PD_T_CC_DEBOUNCE);
> + break;
> + case PR_SWAP_SRC_SNK_SOURCE_OFF_CC_DEBOUNCED:
> /*
> * USB-PD standard, 6.2.1.4, Port Power Role:
> * "During the Power Role Swap Sequence, for the initial Source
> @@ -2709,6 +2717,15 @@ static void run_state_machine(struct tcpm_port *port)
> case PR_SWAP_SNK_SRC_SOURCE_ON:
> tcpm_set_cc(port, tcpm_rp_cc(port));
> tcpm_set_vbus(port, true);
> + /*
> + * allow time VBUS ramp-up, must be < tNewSrc
> + * Also, this window overlaps with CC debounce as well.
> + * So, Wait for the max of two which is PD_T_NEWSRC
> + */
> + tcpm_set_state(port, PR_SWAP_SNK_SRC_SOURCE_ON_VBUS_RAMPED_UP,
> + PD_T_NEWSRC);
> + break;
> + case PR_SWAP_SNK_SRC_SOURCE_ON_VBUS_RAMPED_UP:
> /*
> * USB PD standard, 6.2.1.4:
> * "Subsequent Messages initiated by the Policy Engine,
> @@ -2979,8 +2996,10 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
> case PR_SWAP_SNK_SRC_SINK_OFF:
> case PR_SWAP_SRC_SNK_TRANSITION_OFF:
> case PR_SWAP_SRC_SNK_SOURCE_OFF:
> + case PR_SWAP_SRC_SNK_SOURCE_OFF_CC_DEBOUNCED:
> + case PR_SWAP_SNK_SRC_SOURCE_ON:
> /*
> - * CC state change is expected here; we just turned off power.
> + * CC state change is expected in PR_SWAP
> * Ignore it.
> */
> break;
> --
> 2.14.1.342.g6490525c54-goog
>