From: Ajay Gupta <aj...@nvidia.com>

Cypress USB Type-C CCGx controller firmware verson 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. Many of these cards may get latest kernel but
may not get latest fixed firmware so a workaround is required to
check for any connector change event.

The workaround is that i2c bus driver will call pm_request_resume()
to runtime resume ucsi_ccg 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 <aj...@nvidia.com>
---
 drivers/usb/typec/ucsi/ucsi_ccg.c | 78 +++++++++++++++++++++++++++++--
 1 file changed, 74 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c 
b/drivers/usb/typec/ucsi/ucsi_ccg.c
index cc7094ecda2d..3457e112fdbc 100644
--- a/drivers/usb/typec/ucsi/ucsi_ccg.c
+++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
@@ -109,6 +109,8 @@ struct version_format {
        __le16 build;
        u8 patch;
        u8 ver;
+#define CCG_VERSION_PATCH(x) ((x) << 16)
+#define CCG_VERSION(x) ((x) << 24)
 #define CCG_VERSION_MIN_SHIFT (0)
 #define CCG_VERSION_MIN_MASK (0xf << CCG_VERSION_MIN_SHIFT)
 #define CCG_VERSION_MAJ_SHIFT (4)
@@ -172,6 +174,7 @@ struct ucsi_ccg {
        struct ccg_dev_info info;
        /* version info for boot, primary and secondary */
        struct version_info version[FW2 + 1];
+       u32 fw_version;
        /* CCG HPI communication flags */
        unsigned long flags;
 #define RESET_PENDING  0
@@ -185,6 +188,10 @@ struct ucsi_ccg {
 
        /* fw build with vendor information */
        u16 fw_build;
+       bool run_isr; /* flag to call ISR routine during resume */
+       struct work_struct pm_work;
+       u16 old_fw_build;
+       u32 old_fw_version;
 };
 
 static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
@@ -212,6 +219,17 @@ static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 
*data, u32 len)
        if (quirks && quirks->max_read_len)
                max_read_len = quirks->max_read_len;
 
+       if (uc->old_fw_build == uc->fw_build &&
+           uc->fw_version <= uc->old_fw_version) {
+               mutex_lock(&uc->lock);
+               /* do not schedule pm_work to run ISR in
+                * ucsi_ccg_runtime_resume() after pm_runtime_get_sync()
+                * since we are already in ISR path.
+                */
+               uc->run_isr = false;
+               mutex_unlock(&uc->lock);
+       }
+
        pm_runtime_get_sync(uc->dev);
        while (rem_len > 0) {
                msgs[1].buf = &data[len - rem_len];
@@ -254,6 +272,17 @@ static int ccg_write(struct ucsi_ccg *uc, u16 rab, u8 
*data, u32 len)
        msgs[0].len = len + sizeof(rab);
        msgs[0].buf = buf;
 
+       if (uc->old_fw_build == uc->fw_build &&
+           uc->fw_version <= uc->old_fw_version) {
+               mutex_lock(&uc->lock);
+               /* do not schedule pm_work to run ISR in
+                * ucsi_ccg_runtime_resume() after pm_runtime_get_sync()
+                * since we are already in ISR path.
+                */
+               uc->run_isr = false;
+               mutex_unlock(&uc->lock);
+       }
+
        pm_runtime_get_sync(uc->dev);
        status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
        if (status < 0) {
@@ -383,6 +412,13 @@ static irqreturn_t ccg_irq_handler(int irq, void *data)
        return IRQ_HANDLED;
 }
 
+static void ccg_pm_workaround_work(struct work_struct *pm_work)
+{
+       struct ucsi_ccg *uc = container_of(pm_work, struct ucsi_ccg, pm_work);
+
+       ucsi_notify(uc->ucsi);
+}
+
 static int get_fw_info(struct ucsi_ccg *uc)
 {
        int err;
@@ -392,6 +428,9 @@ static int get_fw_info(struct ucsi_ccg *uc)
        if (err < 0)
                return err;
 
+       uc->fw_version = CCG_VERSION(uc->version[FW2].app.ver) |
+                       CCG_VERSION_PATCH(uc->version[FW2].app.patch);
+
        err = ccg_read(uc, CCGX_RAB_DEVICE_MODE, (u8 *)(&uc->info),
                       sizeof(uc->info));
        if (err < 0)
@@ -740,11 +779,12 @@ static bool ccg_check_fw_version(struct ucsi_ccg *uc, 
const char *fw_name,
        }
 
        /* compare input version with FWCT version */
-       cur_version = le16_to_cpu(app->build) | app->patch << 16 |
-                       app->ver << 24;
+       cur_version = le16_to_cpu(app->build) | CCG_VERSION_PATCH(app->patch) |
+                       CCG_VERSION(app->ver);
 
-       new_version = le16_to_cpu(fw_cfg.app.build) | fw_cfg.app.patch << 16 |
-                       fw_cfg.app.ver << 24;
+       new_version = le16_to_cpu(fw_cfg.app.build) |
+                       CCG_VERSION_PATCH(fw_cfg.app.patch) |
+                       CCG_VERSION(fw_cfg.app.ver);
 
        if (!ccg_check_vendor_version(uc, app, &fw_cfg))
                goto out_release_firmware;
@@ -1084,8 +1124,16 @@ static int ucsi_ccg_probe(struct i2c_client *client,
        uc->ppm.sync = ucsi_ccg_sync;
        uc->dev = dev;
        uc->client = client;
+       uc->run_isr = true;
        mutex_init(&uc->lock);
        INIT_WORK(&uc->work, ccg_update_firmware);
+       INIT_WORK(&uc->pm_work, ccg_pm_workaround_work);
+
+       /* Firmware version 3.1.10 or earlier, built for NVIDIA has known issue
+        * of missing interrupt when a device is connected for runtime resume
+        */
+       uc->old_fw_build = ('n' << 8) | 'v';
+       uc->old_fw_version = CCG_VERSION(0x31) | CCG_VERSION_PATCH(10);
 
        /* Only fail FW flashing when FW build information is not provided */
        status = device_property_read_u16(dev, "ccgx,firmware-build",
@@ -1153,6 +1201,7 @@ static int ucsi_ccg_remove(struct i2c_client *client)
 {
        struct ucsi_ccg *uc = i2c_get_clientdata(client);
 
+       cancel_work_sync(&uc->pm_work);
        cancel_work_sync(&uc->work);
        ucsi_unregister_ppm(uc->ucsi);
        pm_runtime_disable(uc->dev);
@@ -1198,6 +1247,27 @@ static int ucsi_ccg_runtime_suspend(struct device *dev)
 
 static int ucsi_ccg_runtime_resume(struct device *dev)
 {
+       struct i2c_client *client = to_i2c_client(dev);
+       struct ucsi_ccg *uc = i2c_get_clientdata(client);
+       bool schedule = true;
+
+       /* Firmware version "old_fw_version" or earlier, built for NVIDIA has
+        * known issue of missing interrupt when a device is connected for
+        * runtime resume. Schedule a work to call ISR as a workaround.
+        */
+       if (uc->old_fw_build == uc->fw_build &&
+           uc->fw_version <= uc->old_fw_version) {
+               mutex_lock(&uc->lock);
+               if (!uc->run_isr) {
+                       uc->run_isr = true;
+                       schedule = false;
+               }
+               mutex_unlock(&uc->lock);
+
+               if (schedule)
+                       schedule_work(&uc->pm_work);
+       }
+
        return 0;
 }
 
-- 
2.17.1

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