[PATCH v2 4/5] i2c: nvidia-gpu: resume ccgx i2c client

[Ajay Gupta <ajaykuee@gmail.com>]

From: Ajay Gupta <ajayg@nvidia.com>

Cypress USB Type-C CCGx controller firmware version 3.1.10
(which is being used in many NVIDIA GPU cards) has known issue of
not triggering interrupt when a USB device is hot plugged to runtime
resume the controller. If any GPU card gets latest kernel with runtime
pm support but does not get latest fixed firmware then also it should
continue to work and therefore a workaround is required to check for
any connector change event

The workaround is to request runtime resume of i2c client
which is UCSI Cypress CCGx driver. CCG driver will call the ISR
for any connector change event only if NVIDIA GPU has old
CCG firmware with the known issue.

Signed-off-by: Ajay Gupta <ajayg@nvidia.com>
---
Changes from v1->v2:
	Fixed comment from Wolfram by fixing comment style.

 drivers/i2c/busses/i2c-nvidia-gpu.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-nvidia-gpu.c b/drivers/i2c/busses/i2c-nvidia-gpu.c
index af445590041b..6826740fd0f5 100644
--- a/drivers/i2c/busses/i2c-nvidia-gpu.c
+++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
@@ -51,6 +51,7 @@ struct gpu_i2c_dev {
 	void __iomem *regs;
 	struct i2c_adapter adapter;
 	struct i2c_board_info *gpu_ccgx_ucsi;
+	struct i2c_client *ccgx_client;
 };
 
 static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
@@ -271,8 +272,6 @@ static const struct property_entry ccgx_props[] = {
 
 static int gpu_populate_client(struct gpu_i2c_dev *i2cd, int irq)
 {
-	struct i2c_client *ccgx_client;
-
 	i2cd->gpu_ccgx_ucsi = devm_kzalloc(i2cd->dev,
 					   sizeof(*i2cd->gpu_ccgx_ucsi),
 					   GFP_KERNEL);
@@ -284,8 +283,8 @@ static int gpu_populate_client(struct gpu_i2c_dev *i2cd, int irq)
 	i2cd->gpu_ccgx_ucsi->addr = 0x8;
 	i2cd->gpu_ccgx_ucsi->irq = irq;
 	i2cd->gpu_ccgx_ucsi->properties = ccgx_props;
-	ccgx_client = i2c_new_device(&i2cd->adapter, i2cd->gpu_ccgx_ucsi);
-	if (!ccgx_client)
+	i2cd->ccgx_client = i2c_new_device(&i2cd->adapter, i2cd->gpu_ccgx_ucsi);
+	if (!i2cd->ccgx_client)
 		return -ENODEV;
 
 	return 0;
@@ -375,6 +374,13 @@ static __maybe_unused int gpu_i2c_resume(struct device *dev)
 	struct gpu_i2c_dev *i2cd = dev_get_drvdata(dev);
 
 	gpu_enable_i2c_bus(i2cd);
+	/*
+	 * Runtime resume ccgx client so that it can see for any
+	 * connector change event. Old ccg firmware has known
+	 * issue of not triggering interrupt when a device is
+	 * connected to runtime resume the controller.
+	 */
+	pm_request_resume(&i2cd->ccgx_client->dev);
 	return 0;
 }
 
-- 
2.17.1