[U-Boot] [PATCH] usb: kbd: don't use int xfers when polling via ctrl xfers
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com --- Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers. --- common/usb_kbd.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/common/usb_kbd.c b/common/usb_kbd.c index 95912f99c767..81c4d62c632b 100644 --- a/common/usb_kbd.c +++ b/common/usb_kbd.c @@ -475,6 +475,9 @@ static int usb_kbd_probe(struct usb_device *dev, unsigned int ifnum) USB_KBD_BOOT_REPORT_SIZE, data->new, data->intinterval); if (!data->intq) { +#elif defined(CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP) + if (usb_get_report(dev, iface->desc.bInterfaceNumber, + 1, 0, data->new, USB_KBD_BOOT_REPORT_SIZE) < 0) { #else if (usb_submit_int_msg(dev, data->intpipe, data->new, data->intpktsize, data->intinterval) < 0) {
On Friday, November 13, 2015 at 09:34:09 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I initially implemented the control EP polling because I had a keyboard which had issues with interrupt transfers.
Reviewed-by: Marek Vasut marex@denx.de
common/usb_kbd.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/common/usb_kbd.c b/common/usb_kbd.c index 95912f99c767..81c4d62c632b 100644 --- a/common/usb_kbd.c +++ b/common/usb_kbd.c @@ -475,6 +475,9 @@ static int usb_kbd_probe(struct usb_device *dev, unsigned int ifnum) USB_KBD_BOOT_REPORT_SIZE, data->new, data->intinterval); if (!data->intq) { +#elif defined(CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP)
- if (usb_get_report(dev, iface->desc.bInterfaceNumber,
1, 0, data->new, USB_KBD_BOOT_REPORT_SIZE) < 0) {#else if (usb_submit_int_msg(dev, data->intpipe, data->new, data->intpktsize, data->intinterval) < 0) {
Best regards, Marek Vasut
On 11/13/2015 06:16 PM, Marek Vasut wrote:
On Friday, November 13, 2015 at 09:34:09 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I initially implemented the control EP polling because I had a keyboard which had issues with interrupt transfers.
Reviewed-by: Marek Vasut marex@denx.de
Did you intend someone else to apply this?
On Wednesday, December 16, 2015 at 12:35:23 AM, Stephen Warren wrote:
On 11/13/2015 06:16 PM, Marek Vasut wrote:
On Friday, November 13, 2015 at 09:34:09 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I initially implemented the control EP polling because I had a keyboard which had issues with interrupt transfers.
Reviewed-by: Marek Vasut marex@denx.de
Did you intend someone else to apply this?
Is the discussion concluded already? I was under the impression that there was no general agreement.
Otherwise I can pick this of course.
Best regards, Marek Vasut
On 12/15/2015 05:42 PM, Marek Vasut wrote:
On Wednesday, December 16, 2015 at 12:35:23 AM, Stephen Warren wrote:
On 11/13/2015 06:16 PM, Marek Vasut wrote:
On Friday, November 13, 2015 at 09:34:09 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I initially implemented the control EP polling because I had a keyboard which had issues with interrupt transfers.
Reviewed-by: Marek Vasut marex@denx.de
Did you intend someone else to apply this?
Is the discussion concluded already? I was under the impression that there was no general agreement.
Otherwise I can pick this of course.
The last comments in the thread were:
Hans de Goede wrote:
Stephen Warren wrote:
However, I think that fixing the existing "use control transfers" support so that it exclusively uses control transfers is still reasonable?
Ack, as long as we have it, we should fix it. I do believe we should get rid of it in the long run though.
On Wednesday, December 16, 2015 at 03:45:48 AM, Stephen Warren wrote:
On 12/15/2015 05:42 PM, Marek Vasut wrote:
On Wednesday, December 16, 2015 at 12:35:23 AM, Stephen Warren wrote:
On 11/13/2015 06:16 PM, Marek Vasut wrote:
On Friday, November 13, 2015 at 09:34:09 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I initially implemented the control EP polling because I had a keyboard which had issues with interrupt transfers.
Reviewed-by: Marek Vasut marex@denx.de
Did you intend someone else to apply this?
Is the discussion concluded already? I was under the impression that there was no general agreement.
Otherwise I can pick this of course.
The last comments in the thread were:
Hans de Goede wrote:
Stephen Warren wrote:
However, I think that fixing the existing "use control transfers" support so that it exclusively uses control transfers is still reasonable?
Ack, as long as we have it, we should fix it. I do believe we should get rid of it in the long run though.
Oki, in that case, it makes sense to apply this in the short term. Thanks for the reminder, applied!
Best regards, Marek Vasut
Hi,
On 11/13/2015 09:34 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I know of at least 2 issues with using control transfers, and IMHO we should try to just remove support for control transfers from the usb kbd drivers.
The 2 known issues are:
1) I've some cheap wireless keyboards where the usb-dongle does not support the ctrl method of polling and things simply do not work when using it.
2) My USB+DVI kvm switch will report keys as pressed to all connected machines, even those without focus when using the ctrl method (this makes sense since other control methods must work without focus to keep the os on the machine happy).
Regards,
Hans
common/usb_kbd.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/common/usb_kbd.c b/common/usb_kbd.c index 95912f99c767..81c4d62c632b 100644 --- a/common/usb_kbd.c +++ b/common/usb_kbd.c @@ -475,6 +475,9 @@ static int usb_kbd_probe(struct usb_device *dev, unsigned int ifnum) USB_KBD_BOOT_REPORT_SIZE, data->new, data->intinterval); if (!data->intq) { +#elif defined(CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP)
- if (usb_get_report(dev, iface->desc.bInterfaceNumber,
1, 0, data->new, USB_KBD_BOOT_REPORT_SIZE) < 0) {
On 11/15/2015 12:40 PM, Hans de Goede wrote:
Hi,
On 11/13/2015 09:34 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I know of at least 2 issues with using control transfers, and IMHO we should try to just remove support for control transfers from the usb kbd drivers.
The 2 known issues are:
- I've some cheap wireless keyboards where the usb-dongle does not
support the ctrl method of polling and things simply do not work when using it.
- My USB+DVI kvm switch will report keys as pressed to all connected
machines, even those without focus when using the ctrl method (this makes sense since other control methods must work without focus to keep the os on the machine happy).
Interesting; Marek observed the opposite i.e. some keyboards that only worked with control transfers.
However, I think that fixing the existing "use control transfers" support so that it exclusively uses control transfers is still reasonable? Perhaps the issues with control transfers affect my decision not to implement interrupt transfers at all in my USB driver, but probably not this patch.
Perhaps a useful future extension would be to register two keyboard drivers; one explicitly using interrupt transfers and one using control transfers, so that the user can set stdin depending on which mode of operation they want.
Hi,
On 16-11-15 18:16, Stephen Warren wrote:
On 11/15/2015 12:40 PM, Hans de Goede wrote:
Hi,
On 11/13/2015 09:34 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
When CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP is enabled, use a GET_REPORT control transfer to retrieve the initial state of the keyboard. This matches the technique used to poll the keyboard state. This is useful since it eliminates the remaining use of interrupt transfers from the USB keyboard driver, which allows it to work with USB HCD that don't support interrupt transfers.
Cc: Hans de Goede hdegoede@redhat.com Signed-off-by: Stephen Warren swarren@nvidia.com
Are there any disadvantages to using control transfers over interrupt transfers? I'm not aware of any, but I assume there must be a reason that U-Boot typically uses interrupt transfers.
I know of at least 2 issues with using control transfers, and IMHO we should try to just remove support for control transfers from the usb kbd drivers.
The 2 known issues are:
- I've some cheap wireless keyboards where the usb-dongle does not
support the ctrl method of polling and things simply do not work when using it.
- My USB+DVI kvm switch will report keys as pressed to all connected
machines, even those without focus when using the ctrl method (this makes sense since other control methods must work without focus to keep the os on the machine happy).
Interesting; Marek observed the opposite i.e. some keyboards that only worked with control transfers.
Right, that is likely due to a broken host-driver implementation for irq endpoints in u-boot, rather then due to broken hardware though. All significant operating systems by default use interrupt endpoints for keyboards, so a keyboard where those are broken will not sell well.
However, I think that fixing the existing "use control transfers" support so that it exclusively uses control transfers is still reasonable?
Ack, as long as we have it, we should fix it. I do believe we should get rid of it in the long run though.
Perhaps the issues with control transfers affect my decision not to implement interrupt transfers at all in my USB driver, but probably not this patch.
Perhaps a useful future extension would be to register two keyboard drivers; one explicitly using interrupt transfers and one using control transfers, so that the user can set stdin depending on which mode of operation they want.
I do not think that that is necessary. As said I believe that any problems with interrupt transfers are host-driver issues, not hardware issues so they can be fixed. Where as the issues with ctrl transfers are hardware issues which cannot be worked-around.
Regards,
Hans
participants (3)
-
Hans de Goede -
Marek Vasut -
Stephen Warren