On Thu, 8 Nov 2012, Pratyush Anand wrote:
> USB specs says that if an over-current is detected then a hub must switch off
> all affected port, wait to cool down and then switch on.
>
> There are few controllers, which does not follow it, and expects software
> to switch off the port power.
Can you give any examples?
> This patch will add workaround for such controllers.
>
> I think it will not affect others, even if HW switch off the port power.
>
> Signed-off-by: Pratyush Anand <pratyush.an...@st.com>
> ---
> drivers/usb/core/hub.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 1af04bd..6674344 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -4531,6 +4531,9 @@ static void hub_events(void)
>
> dev_dbg(hub_dev, "over-current change on port "
> "%d\n", i);
> + if (hdev == hdev->bus->root_hub)
Normally we test for root hubs by doing:
if (!hdev->parent)
You also might want to avoid turning off the power feature if it is
already off:
if (!hdev->parent && (portstatus &
USB_PORT_STAT_POWER))
> + clear_port_feature(hdev, i,
> + USB_PORT_FEAT_POWER);
> clear_port_feature(hdev, i,
> USB_PORT_FEAT_C_OVER_CURRENT);
> msleep(100); /* Cool down */
Alan Stern
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