* USB Question about devices being reconnected to the host
@ 2020-10-15 12:17 Lucas Tanure
2020-10-15 12:30 ` Greg KH
0 siblings, 1 reply; 3+ messages in thread
From: Lucas Tanure @ 2020-10-15 12:17 UTC (permalink / raw)
To: linux-usb, kernelnewbies
Hi,
I'm learning about USB drivers and I would like to know about
disconnecting and reconnecting usb devices.
I can see my probe function being called and also the disconnect
function. But if I reconnect the device there is no call from the kernel
to notify my driver about the device being reconnected.
I can also see that the module for my driver was not unloaded, so I dont
understand the life cycle of a USB device.
If the module is not unloaded at disconnection and re-loaded for a new
device being connected, how can the driver know the device is there
after a disconnection?
Thanks
Lucas
This is my dmesg for the driver at the end of this email:
[ 34.706041] usb 1-1.1.2: new high-speed USB device number 5 using dwc_otg
[ 34.837647] usb 1-1.1.2: New USB device found, idVendor=04b4,
idProduct=00f1, bcdDevice= 0.00
[ 34.837666] usb 1-1.1.2: New USB device strings: Mfr=1, Product=2,
SerialNumber=0
[ 34.837679] usb 1-1.1.2: Product: FX3
[ 34.837693] usb 1-1.1.2: Manufacturer: Cypress
[ 34.902480] usbdev_probe
[ 34.902681] usbcore: registered new interface driver My USB Device
[ 45.416310] usb 1-1.1.2: USB disconnect, device number 5
[ 45.416655] usbdev_disconnect
[ 61.326035] usb 1-1.1.2: new high-speed USB device number 6 using dwc_otg
[ 61.457674] usb 1-1.1.2: New USB device found, idVendor=04b4,
idProduct=00f1, bcdDevice= 0.00
[ 61.457692] usb 1-1.1.2: New USB device strings: Mfr=1, Product=2,
SerialNumber=0
[ 61.457706] usb 1-1.1.2: Product: FX3
[ 61.457720] usb 1-1.1.2: Manufacturer: Cypress
Driver:
#define DEBUG
#include <linux/of.h>
#include <linux/usb.h>
#include <linux/module.h>
static int usbdev_probe(struct usb_interface *intf, const struct
usb_device_id *id)
{
pr_info("%s", __func__);
return 0;
}
static void usbdev_disconnect(struct usb_interface *intf)
{
pr_info("%s", __func__);
}
static int usbdev_suspend(struct usb_interface *intf, pm_message_t message)
{
pr_err("%s", __func__);
return 0;
}
static int usbdev_resume(struct usb_interface *intf)
{
pr_info("%s", __func__);
return 0;
}
static int usbdev_reset_resume(struct usb_interface *intf)
{
pr_info("%s", __func__);
return 0;
}
static int usbdev_pre_reset(struct usb_interface *intf)
{
pr_info("%s", __func__);
return 0;
}
static int usbdev_post_reset(struct usb_interface *intf)
{
pr_info("%s", __func__);
return 0;
}
static const struct usb_device_id usbdev_id_table[] = {
{ USB_DEVICE(0x04b4, 0x00f1) },
{}
};
MODULE_DEVICE_TABLE(usb, usbdev_id_table);
static struct usb_driver usbdev_driver = {
.name = "My USB Device",
.probe = usbdev_probe,
.disconnect = usbdev_disconnect,
.id_table = usbdev_id_table,
.suspend = usbdev_suspend,
.resume = usbdev_resume,
.reset_resume = usbdev_reset_resume,
.pre_reset = usbdev_pre_reset,
.post_reset = usbdev_post_reset,
};
module_usb_driver(usbdev_driver);
MODULE_AUTHOR("Lucas Tanure <tanure@linux.com>");
MODULE_DESCRIPTION("Driver for My USB device");
MODULE_LICENSE("GPL v2");
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: USB Question about devices being reconnected to the host
2020-10-15 12:17 USB Question about devices being reconnected to the host Lucas Tanure
@ 2020-10-15 12:30 ` Greg KH
2020-10-15 13:22 ` Lucas Tanure
0 siblings, 1 reply; 3+ messages in thread
From: Greg KH @ 2020-10-15 12:30 UTC (permalink / raw)
To: Lucas Tanure; +Cc: linux-usb, kernelnewbies
On Thu, Oct 15, 2020 at 01:17:45PM +0100, Lucas Tanure wrote:
> Hi,
>
> I'm learning about USB drivers and I would like to know about disconnecting
> and reconnecting usb devices.
>
> I can see my probe function being called and also the disconnect function.
> But if I reconnect the device there is no call from the kernel to notify my
> driver about the device being reconnected.
That's not good, your driver should be told this.
> I can also see that the module for my driver was not unloaded, so I dont
> understand the life cycle of a USB device.
Modules are never auto-unloaded.
> If the module is not unloaded at disconnection and re-loaded for a new
> device being connected, how can the driver know the device is there after a
> disconnection?
The probe function should be called, are you sure it isn't?
>
> Thanks
> Lucas
>
> This is my dmesg for the driver at the end of this email:
>
> [ 34.706041] usb 1-1.1.2: new high-speed USB device number 5 using dwc_otg
> [ 34.837647] usb 1-1.1.2: New USB device found, idVendor=04b4,
> idProduct=00f1, bcdDevice= 0.00
> [ 34.837666] usb 1-1.1.2: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [ 34.837679] usb 1-1.1.2: Product: FX3
> [ 34.837693] usb 1-1.1.2: Manufacturer: Cypress
> [ 34.902480] usbdev_probe
> [ 34.902681] usbcore: registered new interface driver My USB Device
> [ 45.416310] usb 1-1.1.2: USB disconnect, device number 5
> [ 45.416655] usbdev_disconnect
> [ 61.326035] usb 1-1.1.2: new high-speed USB device number 6 using dwc_otg
> [ 61.457674] usb 1-1.1.2: New USB device found, idVendor=04b4,
> idProduct=00f1, bcdDevice= 0.00
> [ 61.457692] usb 1-1.1.2: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [ 61.457706] usb 1-1.1.2: Product: FX3
> [ 61.457720] usb 1-1.1.2: Manufacturer: Cypress
That is odd, sorry, don't know what to suggest.
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: USB Question about devices being reconnected to the host
2020-10-15 12:30 ` Greg KH
@ 2020-10-15 13:22 ` Lucas Tanure
0 siblings, 0 replies; 3+ messages in thread
From: Lucas Tanure @ 2020-10-15 13:22 UTC (permalink / raw)
To: Greg KH; +Cc: linux-usb, kernelnewbies
On 10/15/20 1:30 PM, Greg KH wrote:
> On Thu, Oct 15, 2020 at 01:17:45PM +0100, Lucas Tanure wrote:
>> Hi,
>>
>> I'm learning about USB drivers and I would like to know about disconnecting
>> and reconnecting usb devices.
>>
>> I can see my probe function being called and also the disconnect function.
>> But if I reconnect the device there is no call from the kernel to notify my
>> driver about the device being reconnected.
>
> That's not good, your driver should be told this.
>
>> I can also see that the module for my driver was not unloaded, so I dont
>> understand the life cycle of a USB device.
>
> Modules are never auto-unloaded.
>
>> If the module is not unloaded at disconnection and re-loaded for a new
>> device being connected, how can the driver know the device is there after a
>> disconnection?
>
> The probe function should be called, are you sure it isn't?
I re-did the test couple more times and I can see now the probe
function being called.
Thanks
>
>
>>
>> Thanks
>> Lucas
>>
>> This is my dmesg for the driver at the end of this email:
>>
>> [ 34.706041] usb 1-1.1.2: new high-speed USB device number 5 using dwc_otg
>> [ 34.837647] usb 1-1.1.2: New USB device found, idVendor=04b4,
>> idProduct=00f1, bcdDevice= 0.00
>> [ 34.837666] usb 1-1.1.2: New USB device strings: Mfr=1, Product=2,
>> SerialNumber=0
>> [ 34.837679] usb 1-1.1.2: Product: FX3
>> [ 34.837693] usb 1-1.1.2: Manufacturer: Cypress
>> [ 34.902480] usbdev_probe
>> [ 34.902681] usbcore: registered new interface driver My USB Device
>> [ 45.416310] usb 1-1.1.2: USB disconnect, device number 5
>> [ 45.416655] usbdev_disconnect
>> [ 61.326035] usb 1-1.1.2: new high-speed USB device number 6 using dwc_otg
>> [ 61.457674] usb 1-1.1.2: New USB device found, idVendor=04b4,
>> idProduct=00f1, bcdDevice= 0.00
>> [ 61.457692] usb 1-1.1.2: New USB device strings: Mfr=1, Product=2,
>> SerialNumber=0
>> [ 61.457706] usb 1-1.1.2: Product: FX3
>> [ 61.457720] usb 1-1.1.2: Manufacturer: Cypress
>
> That is odd, sorry, don't know what to suggest.
>
> greg k-h
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-10-15 12:30 ` Greg KH
2020-10-15 13:22 ` Lucas Tanure
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