mei: me: fix hw ready reset flow

We cleared H_RST for H_CSR on spurious interrupt generated when ME_RDY
while cleared and not while  ME_RDY is set. The spurious interrupt
is not delivered on all platforms in this case the
driver may fail to initialize.

Cc: stable@vger.kernel.org
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
index a31bc4c36cca8f4680579f8ea4ec65b23c737224..ac76a6377794c8b38001ca4ad73dd11f1a70fee7 100644 (file)
--- a/drivers/misc/mei/hw-me.c
+++ b/drivers/misc/mei/hw-me.c
@@ -181,6 +181,9 @@ static void mei_me_hw_reset_release(struct mei_device *dev)
        hcsr |= H_IG;
        hcsr &= ~H_RST;
        mei_hcsr_set(hw, hcsr);
+
+       /* complete this write before we set host ready on another CPU */
+       mmiowb();
 }
 /**
  * mei_me_hw_reset - resets fw via mei csr register.
@@ -218,6 +221,7 @@ static int mei_me_hw_reset(struct mei_device *dev, bool intr_enable)
 static void mei_me_host_set_ready(struct mei_device *dev)
 {
        struct mei_me_hw *hw = to_me_hw(dev);
+       hw->host_hw_state = mei_hcsr_read(hw);
        hw->host_hw_state |= H_IE | H_IG | H_RDY;
        mei_hcsr_set(hw, hw->host_hw_state);
 }
@@ -646,14 +650,13 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
        /*  check if we need to start the dev */
        if (!mei_host_is_ready(dev)) {
                if (mei_hw_is_ready(dev)) {
+                       mei_me_hw_reset_release(dev);
                        dev_dbg(&dev->pdev->dev, "we need to start the dev.\n");
 
                        dev->recvd_hw_ready = true;
                        wake_up_interruptible(&dev->wait_hw_ready);
                } else {
-
-                       dev_dbg(&dev->pdev->dev, "Reset Completed.\n");
-                       mei_me_hw_reset_release(dev);
+                       dev_dbg(&dev->pdev->dev, "Spurious Interrupt\n");
                }
                goto end;
        }