On Thu, Feb 27, 2020 at 09:14:48AM +0100, Uwe Kleine-König wrote:
> 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.
I'd also go with this solution, so you only have i2c transfers when a
reset gpio is configured/present.
>
> Also I wonder if skipping the initialisation is at least worth a
> pr_info.
+1 for pr_info.
regards;rl
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | https://www.pengutronix.de/ |
