On Mon, Jul 24, 2023 at 06:49:50AM +0000, Stanley Chang[昌育德] wrote:
>
> >
> > On Fri, Jul 07, 2023 at 02:47:00PM +0800, Stanley Chang wrote:
> > > In Realtek SoC, the parameter of usb phy is designed to can dynamic
> > > tuning base on port status. Therefore, add a notify callback of phy
> > > driver when usb port status change.
> > >
> > > The Realtek phy driver is designed to dynamically adjust disconnection
> > > level and calibrate phy parameters. When the device connected bit
> > > changes and when the disconnected bit changes, do port status change
> > notification:
> > >
> > > Check if portstatus is USB_PORT_STAT_CONNECTION and portchange is
> > > USB_PORT_STAT_C_CONNECTION.
> > > 1. The device is connected, the driver lowers the disconnection level and
> > > calibrates the phy parameters.
> > > 2. The device disconnects, the driver increases the disconnect level and
> > > calibrates the phy parameters.
> > >
> > > When controller to notify connect that device is already ready. If we
> > > adjust the disconnection level in notify_connect, the disconnect may
> > > have been triggered at this stage. So we need to change that as early
> > > as possible. Therefore, we add an api to notify phy the port status changes.
> >
> > How do you know that the disconnect will not have already been triggered at
> > this point, when the status changes?
>
> The status change of connection is before port reset.
> In this stage, the device is not port enable, and it will not trigger disconnection.
Ok, then say that here please :)
> > >
> > > Signed-off-by: Stanley Chang <stanley_chang@xxxxxxxxxxx>
> > > ---
> > > v6 to v7 change:
> > > No change
> > > v5 to v6 change:
> > > No change
> > > v4 to v5 change:
> > > No change
> > > v3 to v4 change:
> > > Fix the warning for checkpatch with strict.
> > > v2 to v3 change:
> > > Add more comments about the reason for adding this api
> > > v1 to v2 change:
> > > No change
> > > ---
> > > drivers/usb/core/hub.c | 13 +++++++++++++ include/linux/usb/phy.h |
> > > 13 +++++++++++++
> > > 2 files changed, 26 insertions(+)
> > >
> > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index
> > > a739403a9e45..8433ff89dea6 100644
> > > --- a/drivers/usb/core/hub.c
> > > +++ b/drivers/usb/core/hub.c
> > > @@ -614,6 +614,19 @@ static int hub_ext_port_status(struct usb_hub *hub,
> > int port1, int type,
> > > ret = 0;
> > > }
> > > mutex_unlock(&hub->status_mutex);
> > > +
> > > + if (!ret) {
> > > + struct usb_device *hdev = hub->hdev;
> > > +
> > > + if (hdev && !hdev->parent) {
> >
> > Why the check for no parent? Please document that here in a comment.
>
> I will add a comment :
> /* Only notify roothub. That is, when hdev->parent is empty. */
Also document this that this will only happen for root hub status
changes, that's not obvious in the callback name or documentation or
anywhere else here.
> > > + struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
> > > +
> > > + if (hcd->usb_phy)
> > > +
> > usb_phy_notify_port_status(hcd->usb_phy,
> > > + port1 -
> > 1, *status, *change);
> > > + }
> > > + }
> > > +
> >
> > This is safe to notify with the hub mutex unlocked? Again, a comment would
> > be helpful to future people explaining why that is so.
> >
>
> I will add a comment:
> /*
> * There is no need to lock status_mutex here, because status_mutex
> * protects hub->status, and the phy driver only checks the port
> * status without changing the status.
> */
Looks good, if you do it without the trailing whitespace :)
thanks,
greg k-h
