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From 7e1646c382bbd6dc21a167bf7f0e45afa5ea217e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>
Date: Tue, 4 Dec 2012 10:50:30 +0200
Subject: [PATCH 1/3] uru4000: fix race condition on waiting power up irq

It can come before we finish reading the status register on some
cases. Arm the irq handler early, and fix the state machine to
handle early irq properly.

https://bugs.freedesktop.org/show_bug.cgi?id=57834
---
 libfprint/drivers/uru4000.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/libfprint/drivers/uru4000.c b/libfprint/drivers/uru4000.c
index 541245a..07e26a4 100644
--- a/libfprint/drivers/uru4000.c
+++ b/libfprint/drivers/uru4000.c
@@ -994,16 +994,19 @@ static void init_scanpwr_irq_cb(struct fp_img_dev *dev, int status,
 	uint16_t type, void *user_data)
 {
 	struct fpi_ssm *ssm = user_data;
+	struct uru4k_dev *urudev = dev->priv;
 
 	if (status)
 		fpi_ssm_mark_aborted(ssm, status);
 	else if (type != IRQDATA_SCANPWR_ON)
 		fp_dbg("ignoring interrupt");
-	else if (ssm->cur_state != INIT_AWAIT_SCAN_POWER)
-		fp_err("ignoring scanpwr interrupt due to being in wrong state %d",
-			ssm->cur_state);
-	else
+	else if (ssm->cur_state != INIT_AWAIT_SCAN_POWER) {
+		fp_dbg("early scanpwr interrupt");
+		urudev->scanpwr_irq_timeouts = -1;
+	} else {
+		fp_dbg("late scanpwr interrupt");
 		fpi_ssm_next_state(ssm);
+	}
 }
 
 static void init_scanpwr_timeout(void *user_data)
@@ -1053,14 +1056,21 @@ static void init_run_state(struct fpi_ssm *ssm)
 			fpi_ssm_next_state(ssm);
 		break;
 	case INIT_POWERUP: ;
+		if (!IRQ_HANDLER_IS_RUNNING(urudev)) {
+			fpi_ssm_mark_aborted(ssm, -EIO);
+			break;
+		}
+		urudev->irq_cb_data = ssm;
+		urudev->irq_cb = init_scanpwr_irq_cb;
+
 		struct fpi_ssm *powerupsm = fpi_ssm_new(dev->dev, powerup_run_state,
 			POWERUP_NUM_STATES);
 		powerupsm->priv = dev;
 		fpi_ssm_start_subsm(ssm, powerupsm);
 		break;
 	case INIT_AWAIT_SCAN_POWER:
-		if (!IRQ_HANDLER_IS_RUNNING(urudev)) {
-			fpi_ssm_mark_aborted(ssm, -EIO);
+		if (urudev->scanpwr_irq_timeouts < 0) {
+			fpi_ssm_next_state(ssm);
 			break;
 		}
 
@@ -1073,13 +1083,12 @@ static void init_run_state(struct fpi_ssm *ssm)
 			fpi_ssm_mark_aborted(ssm, -ETIME);
 			break;
 		}
-
-		urudev->irq_cb_data = ssm;
-		urudev->irq_cb = init_scanpwr_irq_cb;
 		break;
 	case INIT_DONE:
-		fpi_timeout_cancel(urudev->scanpwr_irq_timeout);
-		urudev->scanpwr_irq_timeout = NULL;
+		if (urudev->scanpwr_irq_timeout) {
+			fpi_timeout_cancel(urudev->scanpwr_irq_timeout);
+			urudev->scanpwr_irq_timeout = NULL;
+		}
 		urudev->irq_cb_data = NULL;
 		urudev->irq_cb = NULL;
 		fpi_ssm_next_state(ssm);
-- 
1.8.0.1