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* [PATCH v5] platform: cros_ec: Query EC protocol version if EC transitions between RO/RW
@ 2020-01-07 22:06 Yicheng Li
  2020-01-23 21:04 ` Enric Balletbo Serra
       [not found] ` <CGME20200131073925eucas1p25bde5452aaa821435367dbfa9904a476@eucas1p2.samsung.com>
  0 siblings, 2 replies; 6+ messages in thread
From: Yicheng Li @ 2020-01-07 22:06 UTC (permalink / raw)
  To: LKML, bleung, gwendal; +Cc: Yicheng Li

RO and RW of EC may have different EC protocol version. If EC transitions
between RO and RW, but AP does not reboot (this is true for fingerprint
microcontroller / cros_fp, but not true for main ec / cros_ec), the AP
still uses the protocol version queried before transition, which can
cause problems. In the case of fingerprint microcontroller, this causes
AP to send the wrong version of EC_CMD_GET_NEXT_EVENT to RO in the
interrupt handler, which in turn prevents RO to clear the interrupt
line to AP, in an infinite loop.

Once an EC_HOST_EVENT_INTERFACE_READY is received, we know that there
might have been a transition between RO and RW, so re-query the protocol.

Change-Id: I49a51cc10d22a4ab9e75204a4c0c8819d5b3d282
Signed-off-by: Yicheng Li <yichengli@chromium.org>
---
 drivers/platform/chrome/cros_ec.c           | 24 +++++++++++++++++++++
 include/linux/platform_data/cros_ec_proto.h |  3 +++
 2 files changed, 27 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
index 9b2d07422e17..38ec1fb409a5 100644
--- a/drivers/platform/chrome/cros_ec.c
+++ b/drivers/platform/chrome/cros_ec.c
@@ -104,6 +104,23 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)
 	return ret;
 }
 
+static int cros_ec_ready_event(struct notifier_block *nb,
+	unsigned long queued_during_suspend, void *_notify)
+{
+	struct cros_ec_device *ec_dev = container_of(nb, struct cros_ec_device,
+						     notifier_ready);
+	u32 host_event = cros_ec_get_host_event(ec_dev);
+
+	if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_INTERFACE_READY)) {
+		mutex_lock(&ec_dev->lock);
+		cros_ec_query_all(ec_dev);
+		mutex_unlock(&ec_dev->lock);
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
 /**
  * cros_ec_register() - Register a new ChromeOS EC, using the provided info.
  * @ec_dev: Device to register.
@@ -201,6 +218,13 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 		dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
 			err);
 
+	/* Register the notifier for EC_HOST_EVENT_INTERFACE_READY event. */
+	ec_dev->notifier_ready.notifier_call = cros_ec_ready_event;
+	err = blocking_notifier_chain_register(&ec_dev->event_notifier,
+					       &ec_dev->notifier_ready);
+	if (err)
+		return err;
+
 	dev_info(dev, "Chrome EC device registered\n");
 
 	return 0;
diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
index 0d4e4aaed37a..a1c545c464e7 100644
--- a/include/linux/platform_data/cros_ec_proto.h
+++ b/include/linux/platform_data/cros_ec_proto.h
@@ -121,6 +121,8 @@ struct cros_ec_command {
  * @event_data: Raw payload transferred with the MKBP event.
  * @event_size: Size in bytes of the event data.
  * @host_event_wake_mask: Mask of host events that cause wake from suspend.
+ * @notifier_ready: The notifier_block to let the kernel re-query EC
+ *      communication protocol when the EC sends EC_HOST_EVENT_INTERFACE_READY.
  * @ec: The platform_device used by the mfd driver to interface with the
  *      main EC.
  * @pd: The platform_device used by the mfd driver to interface with the
@@ -161,6 +163,7 @@ struct cros_ec_device {
 	int event_size;
 	u32 host_event_wake_mask;
 	u32 last_resume_result;
+	struct notifier_block notifier_ready;
 
 	/* The platform devices used by the mfd driver */
 	struct platform_device *ec;
-- 
2.21.0


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-02-04  7:32 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-07 22:06 [PATCH v5] platform: cros_ec: Query EC protocol version if EC transitions between RO/RW Yicheng Li
2020-01-23 21:04 ` Enric Balletbo Serra
     [not found] ` <CGME20200131073925eucas1p25bde5452aaa821435367dbfa9904a476@eucas1p2.samsung.com>
2020-01-31  7:39   ` Marek Szyprowski
2020-02-03  9:33     ` Enric Balletbo Serra
2020-02-03 12:18       ` Marek Szyprowski
     [not found]         ` <CAB8_tbG-9ntKe3NoMfiDEZsYqbM4U5mK24JNHeikzxG9bkuvGg@mail.gmail.com>
2020-02-04  7:32           ` Marek Szyprowski

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