From e707180ae2df1c87e26ec7a6fd70d07483bde7fd Mon Sep 17 00:00:00 2001 From: Sean Nyekjaer Date: Wed, 4 Dec 2019 11:36:06 +0000 Subject: can: flexcan: fix possible deadlock and out-of-order reception after wakeup When suspending, and there is still CAN traffic on the interfaces the flexcan immediately wakes the platform again. As it should :-). But it throws this error msg: [ 3169.378661] PM: noirq suspend of devices failed On the way down to suspend the interface that throws the error message calls flexcan_suspend() but fails to call flexcan_noirq_suspend(). That means flexcan_enter_stop_mode() is called, but on the way out of suspend the driver only calls flexcan_resume() and skips flexcan_noirq_resume(), thus it doesn't call flexcan_exit_stop_mode(). This leaves the flexcan in stop mode, and with the current driver it can't recover from this even with a soft reboot, it requires a hard reboot. This patch fixes the deadlock when using self wakeup, by calling flexcan_exit_stop_mode() from flexcan_resume() instead of flexcan_noirq_resume(). This also fixes another issue: CAN frames are received out-of-order in first IRQ handler run after wakeup. The problem is that the wakeup latency from frame reception to the IRQ handler (where the CAN frames are sorted by timestamp) is much bigger than the time stamp counter wrap around time. This means it's impossible to sort the CAN frames by timestamp. The reason is that the controller exits stop mode during noirq resume, which means it receives frames immediately, but interrupt handling is still not possible. So exit stop mode during resume stage instead of noirq resume fixes this issue. Fixes: de3578c198c6 ("can: flexcan: add self wakeup support") Signed-off-by: Sean Nyekjaer Tested-by: Sean Nyekjaer Signed-off-by: Joakim Zhang Cc: linux-stable # >= v5.0 Signed-off-by: Marc Kleine-Budde --- drivers/net/can/flexcan.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'drivers/net/can/flexcan.c') diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index a929cdda9ab2..b6f675a5e2d9 100644 --- a/drivers/net/can/flexcan.c +++ b/drivers/net/can/flexcan.c @@ -1722,6 +1722,9 @@ static int __maybe_unused flexcan_resume(struct device *device) netif_start_queue(dev); if (device_may_wakeup(device)) { disable_irq_wake(dev->irq); + err = flexcan_exit_stop_mode(priv); + if (err) + return err; } else { err = pm_runtime_force_resume(device); if (err) @@ -1767,14 +1770,9 @@ static int __maybe_unused flexcan_noirq_resume(struct device *device) { struct net_device *dev = dev_get_drvdata(device); struct flexcan_priv *priv = netdev_priv(dev); - int err; - if (netif_running(dev) && device_may_wakeup(device)) { + if (netif_running(dev) && device_may_wakeup(device)) flexcan_enable_wakeup_irq(priv, false); - err = flexcan_exit_stop_mode(priv); - if (err) - return err; - } return 0; } -- cgit v1.2.3-59-g8ed1b From b7603d080ffcf8689ec91ca300caf84d8dbed317 Mon Sep 17 00:00:00 2001 From: Joakim Zhang Date: Wed, 4 Dec 2019 11:36:11 +0000 Subject: can: flexcan: add low power enter/exit acknowledgment helper The MCR[LPMACK] read-only bit indicates that FlexCAN is in a lower-power mode (Disabled mode, Doze mode, Stop mode). The CPU can poll this bit to know when FlexCAN has actually entered low power mode. The low power enter/exit acknowledgment helper will reduce code duplication for disabled mode, doze mode and stop mode. Tested-by: Sean Nyekjaer Signed-off-by: Joakim Zhang Signed-off-by: Marc Kleine-Budde --- drivers/net/can/flexcan.c | 46 ++++++++++++++++++++++++++++++---------------- 1 file changed, 30 insertions(+), 16 deletions(-) (limited to 'drivers/net/can/flexcan.c') diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index b6f675a5e2d9..9f3a5e56fc37 100644 --- a/drivers/net/can/flexcan.c +++ b/drivers/net/can/flexcan.c @@ -389,6 +389,34 @@ static struct flexcan_mb __iomem *flexcan_get_mb(const struct flexcan_priv *priv (&priv->regs->mb[bank][priv->mb_size * mb_index]); } +static int flexcan_low_power_enter_ack(struct flexcan_priv *priv) +{ + struct flexcan_regs __iomem *regs = priv->regs; + unsigned int timeout = FLEXCAN_TIMEOUT_US / 10; + + while (timeout-- && !(priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) + udelay(10); + + if (!(priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) + return -ETIMEDOUT; + + return 0; +} + +static int flexcan_low_power_exit_ack(struct flexcan_priv *priv) +{ + struct flexcan_regs __iomem *regs = priv->regs; + unsigned int timeout = FLEXCAN_TIMEOUT_US / 10; + + while (timeout-- && (priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) + udelay(10); + + if (priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK) + return -ETIMEDOUT; + + return 0; +} + static void flexcan_enable_wakeup_irq(struct flexcan_priv *priv, bool enable) { struct flexcan_regs __iomem *regs = priv->regs; @@ -506,39 +534,25 @@ static inline int flexcan_transceiver_disable(const struct flexcan_priv *priv) static int flexcan_chip_enable(struct flexcan_priv *priv) { struct flexcan_regs __iomem *regs = priv->regs; - unsigned int timeout = FLEXCAN_TIMEOUT_US / 10; u32 reg; reg = priv->read(®s->mcr); reg &= ~FLEXCAN_MCR_MDIS; priv->write(reg, ®s->mcr); - while (timeout-- && (priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) - udelay(10); - - if (priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK) - return -ETIMEDOUT; - - return 0; + return flexcan_low_power_exit_ack(priv); } static int flexcan_chip_disable(struct flexcan_priv *priv) { struct flexcan_regs __iomem *regs = priv->regs; - unsigned int timeout = FLEXCAN_TIMEOUT_US / 10; u32 reg; reg = priv->read(®s->mcr); reg |= FLEXCAN_MCR_MDIS; priv->write(reg, ®s->mcr); - while (timeout-- && !(priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) - udelay(10); - - if (!(priv->read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) - return -ETIMEDOUT; - - return 0; + return flexcan_low_power_enter_ack(priv); } static int flexcan_chip_freeze(struct flexcan_priv *priv) -- cgit v1.2.3-59-g8ed1b From 048e3a34a2e7669bf475eb56c7345ad9d8d2b8e3 Mon Sep 17 00:00:00 2001 From: Joakim Zhang Date: Wed, 4 Dec 2019 11:36:14 +0000 Subject: can: flexcan: poll MCR_LPM_ACK instead of GPR ACK for stop mode acknowledgment Stop Mode is entered when Stop Mode is requested at chip level and MCR[LPM_ACK] is asserted by the FlexCAN. Double check with IP owner, the MCR[LPM_ACK] bit should be polled for stop mode acknowledgment, not the acknowledgment from chip level which is used to gate flexcan clocks. This patch depends on: b7603d080ffc ("can: flexcan: add low power enter/exit acknowledgment helper") Fixes: 5f186c257fa4 (can: flexcan: fix stop mode acknowledgment) Tested-by: Sean Nyekjaer Signed-off-by: Joakim Zhang Cc: linux-stable # >= v5.0 Signed-off-by: Marc Kleine-Budde --- drivers/net/can/flexcan.c | 17 ++--------------- 1 file changed, 2 insertions(+), 15 deletions(-) (limited to 'drivers/net/can/flexcan.c') diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index 9f3a5e56fc37..94d10ec954a0 100644 --- a/drivers/net/can/flexcan.c +++ b/drivers/net/can/flexcan.c @@ -435,7 +435,6 @@ static void flexcan_enable_wakeup_irq(struct flexcan_priv *priv, bool enable) static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv) { struct flexcan_regs __iomem *regs = priv->regs; - unsigned int ackval; u32 reg_mcr; reg_mcr = priv->read(®s->mcr); @@ -446,36 +445,24 @@ static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv) regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr, 1 << priv->stm.req_bit, 1 << priv->stm.req_bit); - /* get stop acknowledgment */ - if (regmap_read_poll_timeout(priv->stm.gpr, priv->stm.ack_gpr, - ackval, ackval & (1 << priv->stm.ack_bit), - 0, FLEXCAN_TIMEOUT_US)) - return -ETIMEDOUT; - - return 0; + return flexcan_low_power_enter_ack(priv); } static inline int flexcan_exit_stop_mode(struct flexcan_priv *priv) { struct flexcan_regs __iomem *regs = priv->regs; - unsigned int ackval; u32 reg_mcr; /* remove stop request */ regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr, 1 << priv->stm.req_bit, 0); - /* get stop acknowledgment */ - if (regmap_read_poll_timeout(priv->stm.gpr, priv->stm.ack_gpr, - ackval, !(ackval & (1 << priv->stm.ack_bit)), - 0, FLEXCAN_TIMEOUT_US)) - return -ETIMEDOUT; reg_mcr = priv->read(®s->mcr); reg_mcr &= ~FLEXCAN_MCR_SLF_WAK; priv->write(reg_mcr, ®s->mcr); - return 0; + return flexcan_low_power_exit_ack(priv); } static inline void flexcan_error_irq_enable(const struct flexcan_priv *priv) -- cgit v1.2.3-59-g8ed1b