It is possible that the hub was configured earlier by the bootloader and
we lack of the reset-gpio. In such a case the usb251xb_connect() fails
because the registers are write-protected. Add a check to test if the
hub is already connected and don't try to reconfigure the hub if we
can't toggle the reset pin. Don't change the usb251xb_connect() logic
if we can't read the status.
Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
---
drivers/usb/misc/usb251xb.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/drivers/usb/misc/usb251xb.c b/drivers/usb/misc/usb251xb.c
index 29fe5771c21b..9f9a64bab059 100644
--- a/drivers/usb/misc/usb251xb.c
+++ b/drivers/usb/misc/usb251xb.c
@@ -266,6 +266,30 @@ static int usb251x_check_gpio_chip(struct usb251xb *hub)
}
#endif
+static bool usb251xb_hub_attached(struct usb251xb *hub)
+{
+ char i2c_rb;
+ int err;
+
+ err = i2c_smbus_read_block_data(hub->i2c, USB251XB_ADDR_STATUS_COMMAND,
+ &i2c_rb);
+ if (err < 0) {
+ /*
+ * The device disables the i2c-interface immediately after it
+ * received the USB_ATTACH signal.
+ */
+ if (err == -ENXIO)
+ return true;
+
+ dev_warn(hub->dev,
+ "Checking hub Status/Command register failed: %d\n",
+ err);
+ return false;
+ }
+
+ return !!(i2c_rb & USB251XB_STATUS_COMMAND_ATTACH);
+}
+
static void usb251xb_reset(struct usb251xb *hub)
{
if (!hub->gpio_reset)
@@ -288,6 +312,15 @@ static int usb251xb_connect(struct usb251xb *hub)
struct device *dev = hub->dev;
int err, i;
char i2c_wb[USB251XB_I2C_REG_SZ];
+ bool is_attached;
+
+ /*
+ * Check if configuration was done earlier by the bootloader. Trust them
+ * if it is the case and we are not capable to reset the hub.
+ */
+ is_attached = usb251xb_hub_attached(hub);
+ if (!hub->gpio_reset && is_attached)
+ return 0;
memset(i2c_wb, 0, USB251XB_I2C_REG_SZ);
--
2.20.1
