Hi Alan,
On 08/09/21 8:21 pm, Alan Stern wrote:
> On Wed, Sep 08, 2021 at 03:23:10PM +0530, Kishon Vijay Abraham I wrote:
>> It has been observed with certain PCIe USB cards (like Inateck connected
>> to AM64 EVM or J7200 EVM) that as soon as the primary roothub is
>> registered, port status change is handled even before xHC is running
>> leading to cold plug USB devices not detected. For such cases, registering
>> both the root hubs along with the second HCD is required. Add support for
>> deferring roothub registration in usb_add_hcd(), so that both primary and
>> secondary roothubs are registered along with the second HCD.
>>
>> CC: stable@xxxxxxxxxxxxxxx # 5.4+
>> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
>> Suggested-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
>> Tested-by: Chris Chiu <chris.chiu@xxxxxxxxxxxxx>
>> ---
>> drivers/usb/core/hcd.c | 30 ++++++++++++++++++++++++------
>> include/linux/usb/hcd.h | 2 ++
>> 2 files changed, 26 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
>> index 0f8b7c93310e..30bbf4ac4284 100644
>> --- a/drivers/usb/core/hcd.c
>> +++ b/drivers/usb/core/hcd.c
>> @@ -2775,6 +2775,7 @@ int usb_add_hcd(struct usb_hcd *hcd,
>> {
>> int retval;
>> struct usb_device *rhdev;
>> + struct usb_hcd *shared_hcd;
>>
>> if (!hcd->skip_phy_initialization && usb_hcd_is_primary_hcd(hcd)) {
>> hcd->phy_roothub = usb_phy_roothub_alloc(hcd->self.sysdev);
>> @@ -2935,13 +2936,26 @@ int usb_add_hcd(struct usb_hcd *hcd,
>> goto err_hcd_driver_start;
>> }
>>
>> + /* starting here, usbcore will pay attention to the shared HCD roothub */
>> + shared_hcd = hcd->shared_hcd;
>> + if (!usb_hcd_is_primary_hcd(hcd) && shared_hcd && HCD_DEFER_RH_REGISTER(shared_hcd)) {
>> + retval = register_root_hub(shared_hcd);
>> + if (retval != 0)
>> + goto err_register_root_hub;
>> +
>> + if (shared_hcd->uses_new_polling && HCD_POLL_RH(shared_hcd))
>> + usb_hcd_poll_rh_status(shared_hcd);
>> + }
>> +
>> /* starting here, usbcore will pay attention to this root hub */
>> - retval = register_root_hub(hcd);
>> - if (retval != 0)
>> - goto err_register_root_hub;
>> + if (!HCD_DEFER_RH_REGISTER(hcd)) {
>> + retval = register_root_hub(hcd);
>> + if (retval != 0)
>> + goto err_register_root_hub;
>>
>> - if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
>> - usb_hcd_poll_rh_status(hcd);
>> + if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
>> + usb_hcd_poll_rh_status(hcd);
>> + }
>>
>> return retval;
>>
>> @@ -2985,6 +2999,7 @@ EXPORT_SYMBOL_GPL(usb_add_hcd);
>> void usb_remove_hcd(struct usb_hcd *hcd)
>> {
>> struct usb_device *rhdev = hcd->self.root_hub;
>> + unsigned rh_registered;
>
> This really should be a bool, not an unsigned. (Relatively unimportant.)
>
>> dev_info(hcd->self.controller, "remove, state %x\n", hcd->state);
>>
>> @@ -2995,6 +3010,8 @@ void usb_remove_hcd(struct usb_hcd *hcd)
>>
>> dev_dbg(hcd->self.controller, "roothub graceful disconnect\n");
>> spin_lock_irq (&hcd_root_hub_lock);
>> + if (hcd->rh_registered == 1)
>> + rh_registered = 1;
>
> Just say: rh_registered = hcd->rh_registered
>
>> hcd->rh_registered = 0;
>> spin_unlock_irq (&hcd_root_hub_lock);
>>
>> @@ -3004,7 +3021,8 @@ void usb_remove_hcd(struct usb_hcd *hcd)
>> cancel_work_sync(&hcd->died_work);
>>
>> mutex_lock(&usb_bus_idr_lock);
>> - usb_disconnect(&rhdev); /* Sets rhdev to NULL */
>> + if (rh_registered == 1)
>
> Just say: if (rh_registered)
>
>> + usb_disconnect(&rhdev); /* Sets rhdev to NULL */
>
> Didn't the compiler warn about using a possibly uninitialized variable?
I didn't see any. Possibly the warning levels are not correctly set in my setup.
Will address your comment and send the patch.
Thank You,
Kishon
>
> The overall logic looks okay, apart from this one point.
>
> Alan Stern
>
>> mutex_unlock(&usb_bus_idr_lock);
>>
>> /*
>> diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
>> index 548a028f2dab..2c1fc9212cf2 100644
>> --- a/include/linux/usb/hcd.h
>> +++ b/include/linux/usb/hcd.h
>> @@ -124,6 +124,7 @@ struct usb_hcd {
>> #define HCD_FLAG_RH_RUNNING 5 /* root hub is running? */
>> #define HCD_FLAG_DEAD 6 /* controller has died? */
>> #define HCD_FLAG_INTF_AUTHORIZED 7 /* authorize interfaces? */
>> +#define HCD_FLAG_DEFER_RH_REGISTER 8 /* Defer roothub registration */
>>
>> /* The flags can be tested using these macros; they are likely to
>> * be slightly faster than test_bit().
>> @@ -134,6 +135,7 @@ struct usb_hcd {
>> #define HCD_WAKEUP_PENDING(hcd) ((hcd)->flags & (1U << HCD_FLAG_WAKEUP_PENDING))
>> #define HCD_RH_RUNNING(hcd) ((hcd)->flags & (1U << HCD_FLAG_RH_RUNNING))
>> #define HCD_DEAD(hcd) ((hcd)->flags & (1U << HCD_FLAG_DEAD))
>> +#define HCD_DEFER_RH_REGISTER(hcd) ((hcd)->flags & (1U << HCD_FLAG_DEFER_RH_REGISTER))
>>
>> /*
>> * Specifies if interfaces are authorized by default
>> --
>> 2.17.1
>>
