On Thu, Feb 27, 2020 at 08:25:45AM +0100, Marco Felsch wrote:
> 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;
If you write this as:
if (!hub->gpio_reset && usb251xb_hub_attached(hub))
return 0;
you save some i2c transfers in the presence of a reset gpio.
Also I wonder if skipping the initialisation is at least worth a
pr_info.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
