From d944b27df121e2ee854a6c2fad13d6c6300792d4 Mon Sep 17 00:00:00 2001
From: Kai-Heng Feng <kai.heng.feng@canonical.com>
Date: Tue, 24 Mar 2020 23:28:11 +0800
Subject: [PATCH] i2c: nvidia-gpu: Handle timeout correctly in gpu_i2c_check_status()
Git-commit: d944b27df121e2ee854a6c2fad13d6c6300792d4
Patch-mainline: v5.6
References: git-fixes

Nvidia card may come with a "phantom" UCSI device, and its driver gets
stuck in probe routine, prevents any system PM operations like suspend.

There's an unaccounted case that the target time can equal to jiffies in
gpu_i2c_check_status(), let's solve that by using readl_poll_timeout()
instead of jiffies comparison functions.

Fixes: c71bcdcb42a7 ("i2c: add i2c bus driver for NVIDIA GPU")
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Ajay Gupta <ajayg@nvidia.com>
Tested-by: Ajay Gupta <ajayg@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/i2c/busses/i2c-nvidia-gpu.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/busses/i2c-nvidia-gpu.c b/drivers/i2c/busses/i2c-nvidia-gpu.c
index 62e18b4db0ed..f5d25ce00f03 100644
--- a/drivers/i2c/busses/i2c-nvidia-gpu.c
+++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
@@ -8,6 +8,7 @@
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
@@ -75,20 +76,15 @@ static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
 
 static int gpu_i2c_check_status(struct gpu_i2c_dev *i2cd)
 {
-	unsigned long target = jiffies + msecs_to_jiffies(1000);
 	u32 val;
+	int ret;
 
-	do {
-		val = readl(i2cd->regs + I2C_MST_CNTL);
-		if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER))
-			break;
-		if ((val & I2C_MST_CNTL_STATUS) !=
-				I2C_MST_CNTL_STATUS_BUS_BUSY)
-			break;
-		usleep_range(500, 600);
-	} while (time_is_after_jiffies(target));
-
-	if (time_is_before_jiffies(target)) {
+	ret = readl_poll_timeout(i2cd->regs + I2C_MST_CNTL, val,
+				 !(val & I2C_MST_CNTL_CYCLE_TRIGGER) ||
+				 (val & I2C_MST_CNTL_STATUS) != I2C_MST_CNTL_STATUS_BUS_BUSY,
+				 500, 1000 * USEC_PER_MSEC);
+
+	if (ret) {
 		dev_err(i2cd->dev, "i2c timeout error %x\n", val);
 		return -ETIMEDOUT;
 	}
-- 
2.16.4