The "run_isr" flag is used for preventing the driver from calling the interrupt service routine in its runtime resume callback when the driver is expecting completion to a command, but what that basically does is that it hides the real problem. The real problem is that the controller is allowed to suspend in the middle of command execution.

As a more appropriate fix for the problem, using autosuspend delay time that matches UCSI_TIMEOUT_MS (5s). That prevents the controller from suspending while still in the middle of executing a command.

This fixes a potential deadlock. Both ccg_read() and ccg_write() are called with the mutex already taken at least from ccg_send_command(). In ccg_read() and ccg_write, the mutex is only acquired so that run_isr flag can be set.

Fixes: f0e4cd948b91 ("usb: typec: ucsi: ccg: add runtime pm workaround") Cc: stable@vger.kernel.org Signed-off-by: Heikki Krogerus heikki.krogerus@linux.intel.com --- drivers/usb/typec/ucsi/ucsi_ccg.c | 42 +++---------------------------- 1 file changed, 4 insertions(+), 38 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c index 907e20e1a71e..d772fce51905 100644 --- a/drivers/usb/typec/ucsi/ucsi_ccg.c +++ b/drivers/usb/typec/ucsi/ucsi_ccg.c @@ -195,7 +195,6 @@ struct ucsi_ccg {

/* fw build with vendor information */ u16 fw_build; - bool run_isr; /* flag to call ISR routine during resume */ struct work_struct pm_work; };

@@ -224,18 +223,6 @@ static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len) if (quirks && quirks->max_read_len) max_read_len = quirks->max_read_len;

- if (uc->fw_build == CCG_FW_BUILD_NVIDIA && - uc->fw_version <= CCG_OLD_FW_VERSION) { - mutex_lock(&uc->lock); - /* - * Do not schedule pm_work to run ISR in - * ucsi_ccg_runtime_resume() after pm_runtime_get_sync() - * since we are already in ISR path. - */ - uc->run_isr = false; - mutex_unlock(&uc->lock); - } - pm_runtime_get_sync(uc->dev); while (rem_len > 0) { msgs[1].buf = &data[len - rem_len]; @@ -278,18 +265,6 @@ static int ccg_write(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len) msgs[0].len = len + sizeof(rab); msgs[0].buf = buf;

- if (uc->fw_build == CCG_FW_BUILD_NVIDIA && - uc->fw_version <= CCG_OLD_FW_VERSION) { - mutex_lock(&uc->lock); - /* - * Do not schedule pm_work to run ISR in - * ucsi_ccg_runtime_resume() after pm_runtime_get_sync() - * since we are already in ISR path. - */ - uc->run_isr = false; - mutex_unlock(&uc->lock); - } - pm_runtime_get_sync(uc->dev); status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); if (status < 0) { @@ -1130,7 +1105,6 @@ static int ucsi_ccg_probe(struct i2c_client *client, uc->ppm.sync = ucsi_ccg_sync; uc->dev = dev; uc->client = client; - uc->run_isr = true; mutex_init(&uc->lock); INIT_WORK(&uc->work, ccg_update_firmware); INIT_WORK(&uc->pm_work, ccg_pm_workaround_work); @@ -1188,6 +1162,8 @@ static int ucsi_ccg_probe(struct i2c_client *client,

pm_runtime_set_active(uc->dev); pm_runtime_enable(uc->dev); + pm_runtime_use_autosuspend(uc->dev); + pm_runtime_set_autosuspend_delay(uc->dev, 5000); pm_runtime_idle(uc->dev);

return 0; @@ -1229,7 +1205,6 @@ static int ucsi_ccg_runtime_resume(struct device *dev) { struct i2c_client *client = to_i2c_client(dev); struct ucsi_ccg *uc = i2c_get_clientdata(client); - bool schedule = true;

/* * Firmware version 3.1.10 or earlier, built for NVIDIA has known issue @@ -1237,17 +1212,8 @@ static int ucsi_ccg_runtime_resume(struct device *dev) * Schedule a work to call ISR as a workaround. */ if (uc->fw_build == CCG_FW_BUILD_NVIDIA && - uc->fw_version <= CCG_OLD_FW_VERSION) { - mutex_lock(&uc->lock); - if (!uc->run_isr) { - uc->run_isr = true; - schedule = false; - } - mutex_unlock(&uc->lock); - - if (schedule) - schedule_work(&uc->pm_work); - } + uc->fw_version <= CCG_OLD_FW_VERSION) + schedule_work(&uc->pm_work);

return 0; }