FAILED: patch "[PATCH] i2c: designware: fix IO timeout issue for AMD controller" failed to apply to 4.3-stable tree

FAILED: patch "[PATCH] i2c: designware: fix IO timeout issue for AMD controller" failed to apply to 4.3-stable tree

[gregkh]

The patch below does not apply to the 4.3-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 2d244c81481fa5142a2ba6656ab7a8e40c849c27 Mon Sep 17 00:00:00 2001
From: Xiangliang Yu <Xiangliang.Yu@amd.com>
Date: Fri, 11 Dec 2015 20:02:53 +0800
Subject: [PATCH] i2c: designware: fix IO timeout issue for AMD controller

Because of some hardware limitation, AMD I2C controller can't
trigger pending interrupt if interrupt status has been changed
after clearing interrupt status bits. Then, I2C will lost
interrupt and IO timeout.

According to hardware design, this patch implements a workaround
to disable i2c controller interrupt and re-enable i2c interrupt
before exiting ISR.

To reduce the performance impacts on other vendors, use unlikely
function to check flag in ISR.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 8c48b27ba059..de7fbbb374cd 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -813,6 +813,12 @@ static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 tx_aborted:
 	if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) || dev->msg_err)
 		complete(&dev->cmd_complete);
+	else if (unlikely(dev->accessor_flags & ACCESS_INTR_MASK)) {
+		/* workaround to trigger pending interrupt */
+		stat = dw_readl(dev, DW_IC_INTR_MASK);
+		i2c_dw_disable_int(dev);
+		dw_writel(dev, stat, DW_IC_INTR_MASK);
+	}
 
 	return IRQ_HANDLED;
 }
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 1d50898e7b24..9ffb63a60f95 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -111,6 +111,7 @@ struct dw_i2c_dev {
 
 #define ACCESS_SWAP		0x00000001
 #define ACCESS_16BIT		0x00000002
+#define ACCESS_INTR_MASK	0x00000004
 
 extern int i2c_dw_init(struct dw_i2c_dev *dev);
 extern void i2c_dw_disable(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 809579ecb5a4..f03ea71d6519 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -93,6 +93,7 @@ static void dw_i2c_acpi_params(struct platform_device *pdev, char method[],
 static int dw_i2c_acpi_configure(struct platform_device *pdev)
 {
 	struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
+	const struct acpi_device_id *id;
 
 	dev->adapter.nr = -1;
 	dev->tx_fifo_depth = 32;
@@ -106,6 +107,10 @@ static int dw_i2c_acpi_configure(struct platform_device *pdev)
 	dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev->fs_lcnt,
 			   &dev->sda_hold_time);
 
+	id = acpi_match_device(pdev->dev.driver->acpi_match_table, &pdev->dev);
+	if (id && id->driver_data)
+		dev->accessor_flags |= (u32)id->driver_data;
+
 	return 0;
 }
 
@@ -116,7 +121,7 @@ static const struct acpi_device_id dw_i2c_acpi_match[] = {
 	{ "INT3433", 0 },
 	{ "80860F41", 0 },
 	{ "808622C1", 0 },
-	{ "AMD0010", 0 },
+	{ "AMD0010", ACCESS_INTR_MASK },
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, dw_i2c_acpi_match);