[PATCH AUTOSEL 6.6 24/40] HID: mcp2221: Set driver data before I2C adapter add

[PATCH AUTOSEL 6.6 24/40] HID: mcp2221: Set driver data before I2C adapter add

[Sasha Levin]

From: Hamish Martin <hamish.martin@alliedtelesis.co.nz>

[ Upstream commit f2d4a5834638bbc967371b9168c0b481519f7c5e ]

The process of adding an I2C adapter can invoke I2C accesses on that new
adapter (see i2c_detect()).

Ensure we have set the adapter's driver data to avoid null pointer
dereferences in the xfer functions during the adapter add.

This has been noted in the past and the same fix proposed but not
completed. See:
https://lore.kernel.org/lkml/ef597e73-ed71-168e-52af-0d19b03734ac@vigem.de/

Signed-off-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hid/hid-mcp2221.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c
index 72883e0ce7575..b95f31cf0fa21 100644
--- a/drivers/hid/hid-mcp2221.c
+++ b/drivers/hid/hid-mcp2221.c
@@ -1157,12 +1157,12 @@ static int mcp2221_probe(struct hid_device *hdev,
 	snprintf(mcp->adapter.name, sizeof(mcp->adapter.name),
 			"MCP2221 usb-i2c bridge");
 
+	i2c_set_adapdata(&mcp->adapter, mcp);
 	ret = devm_i2c_add_adapter(&hdev->dev, &mcp->adapter);
 	if (ret) {
 		hid_err(hdev, "can't add usb-i2c adapter: %d\n", ret);
 		return ret;
 	}
-	i2c_set_adapdata(&mcp->adapter, mcp);
 
 #if IS_REACHABLE(CONFIG_GPIOLIB)
 	/* Setup GPIO chip */
-- 
2.42.0

[PATCH AUTOSEL 6.6 25/40] HID: mcp2221: Allow IO to start during probe

[Sasha Levin]

From: Hamish Martin <hamish.martin@alliedtelesis.co.nz>

[ Upstream commit 73ce9f1f2741a38f5d27393e627702ae2c46e6f2 ]

During the probe we add an I2C adapter and as soon as we add that adapter
it may be used for a transfer (e.g via the code in i2cdetect()).
Those transfers are not able to complete and time out. This is because the
HID raw_event callback (mcp2221_raw_event) will not be invoked until the
HID device's 'driver_input_lock' is marked up at the completion of the
probe in hid_device_probe(). This starves the driver of the responses it
is waiting for.
In order to allow the I2C transfers to complete while we are still in the
probe, start the IO once we have completed init of the HID device.

This issue seems to have been seen before and a patch was submitted but
it seems it was never accepted. See:
https://lore.kernel.org/all/20221103222714.21566-3-Enrik.Berkhan@inka.de/

Signed-off-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hid/hid-mcp2221.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c
index b95f31cf0fa21..aef0785c91cc2 100644
--- a/drivers/hid/hid-mcp2221.c
+++ b/drivers/hid/hid-mcp2221.c
@@ -1142,6 +1142,8 @@ static int mcp2221_probe(struct hid_device *hdev,
 	if (ret)
 		return ret;
 
+	hid_device_io_start(hdev);
+
 	/* Set I2C bus clock diviser */
 	if (i2c_clk_freq > 400)
 		i2c_clk_freq = 400;
-- 
2.42.0