[PATCH AUTOSEL 4.14 19/21] i2c: acpi: Force bus speed to 400KHz if a Silead touchscreen is present

[PATCH AUTOSEL 4.14 19/21] i2c: acpi: Force bus speed to 400KHz if a Silead touchscreen is present

[Sasha Levin]

From: Hans de Goede <hdegoede@redhat.com>

[ Upstream commit 7574c0db2e68c4d0bae9d415a683bdd8b2a761e9 ]

Many cheap devices use Silead touchscreen controllers. Testing has shown
repeatedly that these touchscreen controllers work fine at 400KHz, but for
unknown reasons do not work properly at 100KHz. This has been seen on
both ARM and x86 devices using totally different i2c controllers.

On some devices the ACPI tables list another device at the same I2C-bus
as only being capable of 100KHz, testing has shown that these other
devices work fine at 400KHz (as can be expected of any recent I2C hw).

This commit makes i2c_acpi_find_bus_speed() always return 400KHz if a
Silead touchscreen controller is present, fixing the touchscreen not
working on devices which ACPI tables' wrongly list another device on the
same bus as only being capable of 100KHz.

Specifically this fixes the touchscreen on the Jumper EZpad 6 m4 not
working.

Reported-by: youling 257 <youling257@gmail.com>
Tested-by: youling 257 <youling257@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[wsa: rewording warning a little]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/i2c-core-acpi.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
index 847d9bf6744c2..df9800aaeac71 100644
--- a/drivers/i2c/i2c-core-acpi.c
+++ b/drivers/i2c/i2c-core-acpi.c
@@ -43,6 +43,7 @@ struct i2c_acpi_lookup {
 	int index;
 	u32 speed;
 	u32 min_speed;
+	u32 force_speed;
 };
 
 static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data)
@@ -240,6 +241,19 @@ i2c_acpi_match_device(const struct acpi_device_id *matches,
 	return acpi_match_device(matches, &client->dev);
 }
 
+static const struct acpi_device_id i2c_acpi_force_400khz_device_ids[] = {
+	/*
+	 * These Silead touchscreen controllers only work at 400KHz, for
+	 * some reason they do not work at 100KHz. On some devices the ACPI
+	 * tables list another device at their bus as only being capable
+	 * of 100KHz, testing has shown that these other devices work fine
+	 * at 400KHz (as can be expected of any recent i2c hw) so we force
+	 * the speed of the bus to 400 KHz if a Silead device is present.
+	 */
+	{ "MSSL1680", 0 },
+	{}
+};
+
 static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 					   void *data, void **return_value)
 {
@@ -258,6 +272,9 @@ static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
 	if (lookup->speed <= lookup->min_speed)
 		lookup->min_speed = lookup->speed;
 
+	if (acpi_match_device_ids(adev, i2c_acpi_force_400khz_device_ids) == 0)
+		lookup->force_speed = 400000;
+
 	return AE_OK;
 }
 
@@ -295,7 +312,16 @@ u32 i2c_acpi_find_bus_speed(struct device *dev)
 		return 0;
 	}
 
-	return lookup.min_speed != UINT_MAX ? lookup.min_speed : 0;
+	if (lookup.force_speed) {
+		if (lookup.force_speed != lookup.min_speed)
+			dev_warn(dev, FW_BUG "DSDT uses known not-working I2C bus speed %d, forcing it to %d\n",
+				 lookup.min_speed, lookup.force_speed);
+		return lookup.force_speed;
+	} else if (lookup.min_speed != UINT_MAX) {
+		return lookup.min_speed;
+	} else {
+		return 0;
+	}
 }
 EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed);
 
-- 
2.20.1

[PATCH AUTOSEL 4.14 20/21] i2c: core: fix use after free in of_i2c_notify

[Sasha Levin]

From: Wen Yang <wenyang@linux.alibaba.com>

[ Upstream commit a4c2fec16f5e6a5fee4865e6e0e91e2bc2d10f37 ]

We can't use "adap->dev" after it has been freed.

Fixes: 5bf4fa7daea6 ("i2c: break out OF support into separate file")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/i2c/i2c-core-of.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-of.c b/drivers/i2c/i2c-core-of.c
index 8d474bb1dc157..17d727e0b8424 100644
--- a/drivers/i2c/i2c-core-of.c
+++ b/drivers/i2c/i2c-core-of.c
@@ -238,14 +238,14 @@ static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
 		}
 
 		client = of_i2c_register_device(adap, rd->dn);
-		put_device(&adap->dev);
-
 		if (IS_ERR(client)) {
 			dev_err(&adap->dev, "failed to create client for '%pOF'\n",
 				 rd->dn);
+			put_device(&adap->dev);
 			of_node_clear_flag(rd->dn, OF_POPULATED);
 			return notifier_from_errno(PTR_ERR(client));
 		}
+		put_device(&adap->dev);
 		break;
 	case OF_RECONFIG_CHANGE_REMOVE:
 		/* already depopulated? */
-- 
2.20.1