Horrible hack to fix I2C power management bug
If an IRQ occurs while we are trying to go into suspend, the I2C
driver can end up shutting down in the middle of an I2C transaction.
This hack bumps the usage_count of the I2C driver to prevent it
from going into suspend while we're trying to read data from the
MCU. Also adds a bit of debug output if a timeout ever occurs.
Change-Id: Ibb2bf27a88a0822e4b248746b10a4d47138b662b
diff --git a/drivers/input/misc/glasshub.c b/drivers/input/misc/glasshub.c
index e742811..c68f7ff 100644
--- a/drivers/input/misc/glasshub.c
+++ b/drivers/input/misc/glasshub.c
@@ -216,6 +216,15 @@
#define FLAG_PAUSE_FOR_AUDIO 2
/*
+ * Enables horrible hack to fix a power management problem.
+ * We grab a pointer to the OMAP I2C-4 driver so we can do a
+ * pm_runtime_get() call on it to keep it from suspending in
+ * the middle of a the threaded IRQ handler.
+ */
+#define PM_HACK 1
+#define I2C_DEVICE_NAME "omap_i2c.4"
+
+/*
* Basic theory of operation:
*
* The glass hub device comes up in bootloader mode. This mode supports only 5 commands:
@@ -271,6 +280,9 @@
struct i2c_client *i2c_client;
struct input_dev *ps_input_dev;
const struct glasshub_platform_data *pdata;
+#if PM_HACK
+ struct device *i2c_dev;
+#endif
uint8_t *fw_image;
uint32_t fw_dirty[FIRMWARE_NUM_DIRTY_BITS];
int flash_status;
@@ -569,7 +581,8 @@
return rc;
}
-/* Threaded interrupt handler. This is where the real work gets done.
+/*
+ * Threaded interrupt handler. This is where the real work gets done.
* We grab a mutex to prevent I/O requests from user space from
* running concurrently. The timestamp for critical operations comes
* from the main interrupt handler.
@@ -587,6 +600,12 @@
/* increment usage count to prevent suspend */
pm_runtime_get_sync(&glasshub->i2c_client->dev);
+#if PM_HACK
+ /* hack to keep I2C-4 bus from suspending */
+ if (glasshub->i2c_dev)
+ pm_runtime_get_sync(glasshub->i2c_dev);
+#endif
+
/* clear in-service flag */
timestamp = glasshub->irq_timestamp;
set_bit(FLAG_HANDLER_RUNNING, &glasshub->flags);
@@ -612,7 +631,12 @@
/* read the IRQ source */
rc = _i2c_read_reg8(glasshub, REG_STATUS, &status);
- if (rc) goto Error;
+ if (rc) {
+ dev_err(&glasshub->i2c_client->dev,
+ "%s: Error reading status register\n",
+ __FUNCTION__);
+ goto Error;
+ }
glasshub->last_irq_status = status;
/* process prox data */
@@ -621,7 +645,12 @@
/* read value */
rc = _i2c_read_reg(glasshub, REG16_PROX_DATA, &value);
- if (rc) goto Error;
+ if (rc) {
+ dev_err(&glasshub->i2c_client->dev,
+ "%s: Error reading prox data register, count = %d\n",
+ __FUNCTION__, prox_count);
+ goto Error;
+ }
/* shouldn't happen, but 0xffff indicates we read past end of buffer */
if (value == 0xffff) {
@@ -638,7 +667,12 @@
{
unsigned frame_count;
rc = _i2c_read_reg(glasshub, REG16_FRAME_COUNT, &frame_count);
- if (rc) goto Error;
+ if (rc) {
+ dev_err(&glasshub->i2c_client->dev,
+ "%s: Error reading frame count register\n",
+ __FUNCTION__);
+ goto Error;
+ }
printk("%s: Frame count = %u\n", __func__, frame_count);
}
@@ -729,7 +763,12 @@
/* process don/doff */
if (status & IRQ_DON_DOFF) {
rc = _i2c_read_reg8(glasshub, REG_DON_DOFF, &glasshub->don_doff_state);
- if (rc) goto Error;
+ if (rc) {
+ dev_err(&glasshub->i2c_client->dev,
+ "%s: Error reading don/doff register\n",
+ __FUNCTION__);
+ goto Error;
+ }
dev_info(&glasshub->i2c_client->dev, "%s: don/doff state = %u\n",
__FUNCTION__, glasshub->don_doff_state);
sysfs_notify(&glasshub->i2c_client->dev.kobj, NULL, "don_doff");
@@ -759,6 +798,13 @@
/* decrement usage count to allow suspend */
pm_runtime_put_sync(&glasshub->i2c_client->dev);
+
+#if PM_HACK
+ /* hack to keep I2C-4 bus from suspending */
+ if (glasshub->i2c_dev)
+ pm_runtime_put_sync(glasshub->i2c_dev);
+#endif
+
return IRQ_HANDLED;
}
@@ -2326,7 +2372,7 @@
struct glasshub_data *glasshub = NULL;
int rc;
- dev_info(&i2c_client->dev, "%s: Probing glasshub...\n", __FUNCTION__);
+ dev_info(&i2c_client->dev, "%s: Probe glasshub...\n", __FUNCTION__);
glasshub = kzalloc(sizeof(struct glasshub_data), GFP_KERNEL);
if (!glasshub)
{
@@ -2335,6 +2381,24 @@
return -ENOMEM;
}
+#if PM_HACK
+ /* hack to keep I2C-4 bus from suspending */
+ {
+ struct device *p = &i2c_client->dev;
+ while (p) {
+ if (!strcmp(dev_name(p), I2C_DEVICE_NAME)) {
+ glasshub->i2c_dev = p;
+ break;
+ }
+ p = p->parent;
+ }
+ if (!glasshub->i2c_dev)
+ dev_warn(&i2c_client->dev,
+ "%s: Unable to find parent I2C driver\n",
+ __FUNCTION__);
+ }
+#endif
+
/* initialize data structure */
glasshub->i2c_client = i2c_client;
glasshub->flags = 0;
