[RFC usb-next v5 3/3] usb: core: hcd: integrate the PHY roothub wrapper

[Martin Blumenstingl]

Hi Alan,

On Mon, Oct 9, 2017 at 7:18 PM, Alan Stern <stern at rowland.harvard.edu> wrote:
> On Sun, 8 Oct 2017, Martin Blumenstingl wrote:
>
>> This integrates the PHY roothub wrapper into the core hcd
>> infrastructure. Multiple PHYs which are part of the roothub devicetree
>> node (which is a sub-node of the sysdev's node) are now managed
>> (= powered on/off when needed), by the new usb_phy_roothub code.
>>
>> One example where this is required is the Amlogic GXL and GXM SoCs:
>> They are using a dwc3 USB controller with up to three ports enabled on
>> the internal roothub. Using only the top-level "phy" properties does not
>> work here since one can only specify one "usb2-phy" and one "usb3-phy",
>> while actually at least two "usb2-phy" have to be specified.
>>
>> Signed-off-by: Martin Blumenstingl <martin.blumenstingl at googlemail.com>
>> ---
>>  drivers/usb/core/hcd.c  | 30 +++++++++++++++++++++++++++++-
>>  include/linux/usb/hcd.h |  1 +
>>  2 files changed, 30 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
>> index 67aa3d039b9b..56704dd10c15 100644
>> --- a/drivers/usb/core/hcd.c
>> +++ b/drivers/usb/core/hcd.c
>> @@ -50,6 +50,7 @@
>>  #include <linux/usb/otg.h>
>>
>>  #include "usb.h"
>> +#include "phy.h"
>>
>>
>>  /*-------------------------------------------------------------------------*/
>> @@ -2292,7 +2293,11 @@ int hcd_bus_suspend(struct usb_device *rhdev, pm_message_t msg)
>>               dev_dbg(&rhdev->dev, "bus %s fail, err %d\n",
>>                               "suspend", status);
>>       }
>> -     return status;
>> +
>> +     if (status == 0)
>> +             return usb_phy_roothub_power_off(hcd->phy_roothub);
>
> Is this really the right thing to do?  If usb_phy_roothub_power_off()
> fails, what condition does this leave the bus in?  And what condition
> does the kernel _think_ the bus is in?
indeed, thank you for spotting this!

do you have any suggestions how to improve this?
maybe I should move usb_phy_roothub_power_off a few lines up and only
call it after the "rhdev->do_remote_wakeup" block if status is 0. if
usb_phy_roothub_power_off then returns an error I could call
"hcd_bus_resume(rhdev, PMSG_AUTO_RESUME);". what do you think about
this?

> Alan Stern
>


Regards,
Martin