mei: ME hardware reset needs to be synchronized

This fixes failure during initialization on Lynx Point LP devices.

ME driver needs to release the device from the reset
only after the FW has completed its flow and indicated
it by delivering an interrupt to the host.

This is the correct behavior for all the ME devices yet the
the previous versions are less susceptive to the implementation
that ignored FW reset completion indication.

We add mei_me_hw_reset_release function which is called
after reset from the interrupt thread or directly
from mei_reset during power down.

Signed-off-by: Tomas Winkler <tomas.winkler@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 45ea7185c003d5b5deee66ad1a274c23212ed77f..642c6223fa6cd177f22c66e40b3d3531a6d841a4 100644 (file)
--- a/drivers/misc/mei/hw-me.c
+++ b/drivers/misc/mei/hw-me.c
@@ -151,6 +151,20 @@ static void mei_me_intr_disable(struct mei_device *dev)
        mei_hcsr_set(hw, hcsr);
 }
 
+/**
+ * mei_me_hw_reset_release - release device from the reset
+ *
+ * @dev: the device structure
+ */
+static void mei_me_hw_reset_release(struct mei_device *dev)
+{
+       struct mei_me_hw *hw = to_me_hw(dev);
+       u32 hcsr = mei_hcsr_read(hw);
+
+       hcsr |= H_IG;
+       hcsr &= ~H_RST;
+       mei_hcsr_set(hw, hcsr);
+}
 /**
  * mei_me_hw_reset - resets fw via mei csr register.
  *
@@ -169,18 +183,14 @@ static void mei_me_hw_reset(struct mei_device *dev, bool intr_enable)
        if (intr_enable)
                hcsr |= H_IE;
        else
-               hcsr &= ~H_IE;
-
-       mei_hcsr_set(hw, hcsr);
-
-       hcsr = mei_hcsr_read(hw) | H_IG;
-       hcsr &= ~H_RST;
+               hcsr |= ~H_IE;
 
        mei_hcsr_set(hw, hcsr);
 
-       hcsr = mei_hcsr_read(hw);
+       if (dev->dev_state == MEI_DEV_POWER_DOWN)
+               mei_me_hw_reset_release(dev);
 
-       dev_dbg(&dev->pdev->dev, "current HCSR = 0x%08x.\n", hcsr);
+       dev_dbg(&dev->pdev->dev, "current HCSR = 0x%08x.\n", mei_hcsr_read(hw));
 }
 
 /**
@@ -466,7 +476,8 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
                        mutex_unlock(&dev->device_lock);
                        return IRQ_HANDLED;
                } else {
-                       dev_dbg(&dev->pdev->dev, "FW not ready.\n");
+                       dev_dbg(&dev->pdev->dev, "Reset Completed.\n");
+                       mei_me_hw_reset_release(dev);
                        mutex_unlock(&dev->device_lock);
                        return IRQ_HANDLED;
                }