HID: intel-ish: ipc: handle PIMR before ish_wakeup also clear PISR busy_clear bit

Host driver should handle interrupt mask register earlier than wake up ish FW
else there will be conditions when FW interrupt comes, host PIMR register still
not set ready, so move the interrupt mask setting before ish_wakeup.

Clear PISR busy_clear bit in ish_irq_handler. If not clear, there will be
conditions host driver received a busy_clear interrupt (before the busy_clear
mask bit is ready), it will return IRQ_NONE after check_generated_interrupt,
the interrupt will never be cleared, causing the DEVICE not sending following
IRQ.

Since PISR clear should not be called for the CHV device we do this change.
After the change, both ISH2HOST interrupt and busy_clear interrupt will be
considered as interrupt from ISH, busy_clear interrupt will return IRQ_HANDLED
from IPC_IS_BUSY check.
Signed-off-by: Song Hongyan <hongyan.song@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/intel-ish-hid/ipc/ipc.c

@@ -91,7 +91,10 @@ static bool check_generated_interrupt(struct ishtp_device *dev)
 			IPC_INT_FROM_ISH_TO_HOST_CHV_AB(pisr_val);
 	} else {
 		pisr_val = ish_reg_read(dev, IPC_REG_PISR_BXT);
-		interrupt_generated = IPC_INT_FROM_ISH_TO_HOST_BXT(pisr_val);
+		interrupt_generated = !!pisr_val;
+		/* only busy-clear bit is RW, others are RO */
+		if (pisr_val)
+			ish_reg_write(dev, IPC_REG_PISR_BXT, pisr_val);
 	}
 
 	return interrupt_generated;
@@ -839,11 +842,11 @@ int ish_hw_start(struct ishtp_device *dev)
 {
 	ish_set_host_rdy(dev);
 
+	set_host_ready(dev);
+
 	/* After that we can enable ISH DMA operation and wakeup ISHFW */
 	ish_wakeup(dev);
 
-	set_host_ready(dev);
-
 	/* wait for FW-initiated reset flow */
 	if (!dev->recvd_hw_ready)
 		wait_event_interruptible_timeout(dev->wait_hw_ready,