On Wed, Jul 20, 2022 at 09:18:50AM +0200, Alexander Stein wrote:
> Am Freitag, 15. Juli 2022, 21:50:41 CEST schrieb Matthias Kaehlcke:
> > On Fri, Jul 15, 2022 at 09:33:00AM +0200, Alexander Stein wrote:
> > > This is a 4-port 3.0 USB hub.
> > >
> > > Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > > ---
> > > Changes in v2:
> > > * Add devtype data containing waiting times
> > >
> > > drivers/usb/misc/onboard_usb_hub.c | 3 +++
> > > drivers/usb/misc/onboard_usb_hub.h | 7 +++++++
> > > 2 files changed, 10 insertions(+)
> > >
> > > diff --git a/drivers/usb/misc/onboard_usb_hub.c
> > > b/drivers/usb/misc/onboard_usb_hub.c index 1dd7f4767def..319b4b1748fb
> > > 100644
> > > --- a/drivers/usb/misc/onboard_usb_hub.c
> > > +++ b/drivers/usb/misc/onboard_usb_hub.c
> > > @@ -339,6 +339,7 @@ static struct platform_driver onboard_hub_driver = {
> > >
> > > /************************** USB driver **************************/
> > >
> > > #define VENDOR_ID_REALTEK 0x0bda
> > >
> > > +#define VENDOR_ID_TI 0x0451
> > >
> > > /*
> > >
> > > * Returns the onboard_hub platform device that is associated with the
> > > USB
> > >
> > > @@ -416,6 +417,8 @@ static const struct usb_device_id
> > > onboard_hub_id_table[] = {>
> > > { USB_DEVICE(VENDOR_ID_REALTEK, 0x5411) }, /* RTS5411 USB 2.1 */
> > > { USB_DEVICE(VENDOR_ID_REALTEK, 0x0414) }, /* RTS5414 USB 3.2 */
> > > { USB_DEVICE(VENDOR_ID_REALTEK, 0x5414) }, /* RTS5414 USB 2.1 */
> > >
> > > + { USB_DEVICE(VENDOR_ID_TI, 0x8140) }, /* TI USB8041 3.0 */
> > > + { USB_DEVICE(VENDOR_ID_TI, 0x8142) }, /* TI USB8041 2.0 */
> > >
> > > {}
> > >
> > > };
> > > MODULE_DEVICE_TABLE(usb, onboard_hub_id_table);
> > >
> > > diff --git a/drivers/usb/misc/onboard_usb_hub.h
> > > b/drivers/usb/misc/onboard_usb_hub.h index 7e743f4c8aaa..fcb6a9024bbd
> > > 100644
> > > --- a/drivers/usb/misc/onboard_usb_hub.h
> > > +++ b/drivers/usb/misc/onboard_usb_hub.h
> > > @@ -11,7 +11,14 @@ struct onboard_hub_devtype_data {
> > >
> > > unsigned long reset_duration; /* reset pulse width in
> us */
> > >
> > > };
> > >
> > > +static const struct onboard_hub_devtype_data ti_tusb8041_data = {
> > > + .power_stable_time = 3000,
> > > + .reset_duration = 3000,
> >
> > Aren't these two values actually the same thing, i.e. the minimum
> > duration of the reset?
> >
> > From the data sheet:
> >
> > A minimum reset duration of 3 ms is required
> >
> > td2: VDD and VDD33 stable before de-assertion of GRSTz (>= 3ms)
> >
> > My understanding is that td2 is just another expression of the first
> > requirement.
>
> They may have the same values, but IMHO they are applied differently.
> 'power_stable_time' (or power_stable_us now) applies after supplying power,
> while 'reset_duration' (or reset_us now) applies when you deassert the reset
> line.
> For that reason I would like to keep them separated.
In both cases the datasheet talks about the reset duration of 3 ms in
relation with the power supplies:
7.6 Timing Requirements, Power-Up
td2: VDD and VDD33 stable before de-assertion of GRSTz
8.3.7 Power-Up and Reset
A minimum reset duration of 3 ms is required. This is defined as the time when
the power supplies are in the recommended operating range to the de-assertion
of GRSTz.
At this point I see no good reason for having two different values. If it turns
out later that it is really needed for other hubs another fiels like
'power_stable_us' can still be added.
