linux-kernel - [char-misc-next 2/2] mei: me: generate an interrupt if the hw indicates reset.

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Date:   Thu,  2 Feb 2017 11:26:54 +0200
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next 2/2] mei: me: generate an interrupt if the hw indicates reset.

From: Alexander Usyskin <alexander.usyskin@...el.com>

In rare case the driver may lose connection with the device after device
reset due to a missed interrupt. The driver will unlock the flow by
generating an interrupt towards the firmware (HIG) when the device is in
the resetting state. The FW is able to ignore the interrupt during
orderly flow. The effected platforms are skylake and newer.

Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/misc/mei/hw-me.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
index 23294b845c42..71216affcab1 100644
--- a/drivers/misc/mei/hw-me.c
+++ b/drivers/misc/mei/hw-me.c
@@ -394,6 +394,19 @@ static bool mei_me_hw_is_ready(struct mei_device *dev)
 }
 
 /**
+ * mei_me_hw_is_resetting - check whether the me(hw) is in reset
+ *
+ * @dev: mei device
+ * Return: bool
+ */
+static bool mei_me_hw_is_resetting(struct mei_device *dev)
+{
+	u32 mecsr = mei_me_mecsr_read(dev);
+
+	return (mecsr & ME_RST_HRA) == ME_RST_HRA;
+}
+
+/**
  * mei_me_hw_ready_wait - wait until the me(hw) has turned ready
  *  or timeout is reached
  *
@@ -1219,6 +1232,9 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
 		goto end;
 	}
 
+	if (mei_me_hw_is_resetting(dev))
+		mei_hcsr_set_hig(dev);
+
 	mei_me_pg_intr(dev, me_intr_src(hcsr));
 
 	/*  check if we need to start the dev */
-- 
2.7.4