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>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
index a31bc4c36cca..ac76a6377794 100644
--- 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;
         }