From: Douglas Gilbert dgilbert@interlog.com
commit c215e48e97d232249a33849fc46fc50311043e11 upstream.
Augmented Power Delivery Objects (A)PDO_s are used by USB-C PD power adapters to advertize the voltages and currents they support. There can be up to 7 PDO_s but before PPS (programmable power supply) there were seldom more than 4 or 5. Recently Samsung released an optional PPS 45 Watt power adapter (EP-TA485) that has 7 PDO_s. It is for the Galaxy 10+ tablet and charges it quicker than the adapter supplied at purchase. The EP-TA485 causes an overzealous WARN_ON to soil the log plus it miscalculates the number of bytes to read.
So this bug has been there for some time but goes undetected for the majority of USB-C PD power adapters on the market today that have 6 or less PDO_s. That may soon change as more USB-C PD adapters with PPS come to market.
Tested on a EP-TA485 and an older Lenovo PN: SA10M13950 USB-C 65 Watt adapter (without PPS and has 4 PDO_s) plus several other PD power adapters.
Signed-off-by: Douglas Gilbert dgilbert@interlog.com Reviewed-by: Guenter Roeck linux@roeck-us.net Cc: stable stable@vger.kernel.org Link: https://lore.kernel.org/r/20191230033544.1809-1-dgilbert@interlog.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/typec/tcpm/tcpci.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)
--- a/drivers/usb/typec/tcpm/tcpci.c +++ b/drivers/usb/typec/tcpm/tcpci.c @@ -432,20 +432,30 @@ irqreturn_t tcpci_irq(struct tcpci *tcpc
if (status & TCPC_ALERT_RX_STATUS) { struct pd_message msg; - unsigned int cnt; + unsigned int cnt, payload_cnt; u16 header;
regmap_read(tcpci->regmap, TCPC_RX_BYTE_CNT, &cnt); + /* + * 'cnt' corresponds to READABLE_BYTE_COUNT in section 4.4.14 + * of the TCPCI spec [Rev 2.0 Ver 1.0 October 2017] and is + * defined in table 4-36 as one greater than the number of + * bytes received. And that number includes the header. So: + */ + if (cnt > 3) + payload_cnt = cnt - (1 + sizeof(msg.header)); + else + payload_cnt = 0;
tcpci_read16(tcpci, TCPC_RX_HDR, &header); msg.header = cpu_to_le16(header);
- if (WARN_ON(cnt > sizeof(msg.payload))) - cnt = sizeof(msg.payload); + if (WARN_ON(payload_cnt > sizeof(msg.payload))) + payload_cnt = sizeof(msg.payload);
- if (cnt > 0) + if (payload_cnt > 0) regmap_raw_read(tcpci->regmap, TCPC_RX_DATA, - &msg.payload, cnt); + &msg.payload, payload_cnt);
/* Read complete, clear RX status alert bit */ tcpci_write16(tcpci, TCPC_ALERT, TCPC_ALERT_RX_STATUS);