There is a potential delay in notifying Linux USB drivers of downstream
USB bus activity when connecting a high-speed or superSpeed device via the
Microchip USB491x hub. This delay is due to the fixed bInterval value of
12 in the silicon of the Microchip USB491x hub.
Microchip requested to ignore the device descriptor and decrease that
value to 9 as it was too late to modify that in silicon.
This patch speeds up the USB enummeration process that helps to pass
Apple Carplay certifications and improve the User experience when utilizing
the USB device via Microchip Multihost USB491x Hub.
A new hub quirk HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL speeds up
the notification process for Microchip USB491x hub by limiting
the maximum bInterval value to 9.
Signed-off-by: Hardik Gajjar <[email protected]>
---
changes since version 1:
- Move implementation from config.c and quirk.c to hub.c as this is hub
specific changes.
- Improve commit message.
- Link to v1 - https://lore.kernel.org/all/[email protected]/
---
drivers/usb/core/hub.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index b4584a0cd484..3d26d942fcae 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -47,12 +47,18 @@
#define USB_VENDOR_TEXAS_INSTRUMENTS 0x0451
#define USB_PRODUCT_TUSB8041_USB3 0x8140
#define USB_PRODUCT_TUSB8041_USB2 0x8142
+#define USB_VENDOR_MICROCHIP 0x0424
+#define USB_PRODUCT_USB4913 0x4913
+#define USB_PRODUCT_USB4914 0x4914
+#define USB_PRODUCT_USB4915 0x4915
#define HUB_QUIRK_CHECK_PORT_AUTOSUSPEND 0x01
#define HUB_QUIRK_DISABLE_AUTOSUSPEND 0x02
+#define HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL 0x08
#define USB_TP_TRANSMISSION_DELAY 40 /* ns */
#define USB_TP_TRANSMISSION_DELAY_MAX 65535 /* ns */
#define USB_PING_RESPONSE_TIME 400 /* ns */
+#define USB_REDUCE_FRAME_INTR_BINTERVAL 9
/* Protect struct usb_device->state and ->children members
* Note: Both are also protected by ->dev.sem, except that ->state can
@@ -1927,6 +1933,12 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
usb_autopm_get_interface_no_resume(intf);
}
+ if ((id->driver_info & HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL) &&
+ desc->endpoint[0].desc.bInterval > USB_REDUCE_FRAME_INTR_BINTERVAL) {
+ desc->endpoint[0].desc.bInterval =
+ USB_REDUCE_FRAME_INTR_BINTERVAL;
+ }
+
if (hub_configure(hub, &desc->endpoint[0].desc) >= 0) {
onboard_hub_create_pdevs(hdev, &hub->onboard_hub_devs);
@@ -5918,6 +5930,21 @@ static const struct usb_device_id hub_id_table[] = {
.idVendor = USB_VENDOR_TEXAS_INSTRUMENTS,
.idProduct = USB_PRODUCT_TUSB8041_USB3,
.driver_info = HUB_QUIRK_DISABLE_AUTOSUSPEND},
+ { .match_flags = USB_DEVICE_ID_MATCH_VENDOR
+ | USB_DEVICE_ID_MATCH_PRODUCT,
+ .idVendor = USB_VENDOR_MICROCHIP,
+ .idProduct = USB_PRODUCT_USB4913,
+ .driver_info = HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL},
+ { .match_flags = USB_DEVICE_ID_MATCH_VENDOR
+ | USB_DEVICE_ID_MATCH_PRODUCT,
+ .idVendor = USB_VENDOR_MICROCHIP,
+ .idProduct = USB_PRODUCT_USB4914,
+ .driver_info = HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL},
+ { .match_flags = USB_DEVICE_ID_MATCH_VENDOR
+ | USB_DEVICE_ID_MATCH_PRODUCT,
+ .idVendor = USB_VENDOR_MICROCHIP,
+ .idProduct = USB_PRODUCT_USB4915,
+ .driver_info = HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL},
{ .match_flags = USB_DEVICE_ID_MATCH_DEV_CLASS,
.bDeviceClass = USB_CLASS_HUB},
{ .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS,
--
2.17.1
On Thu, Nov 30, 2023 at 09:48:55AM +0100, Hardik Gajjar wrote:
> There is a potential delay in notifying Linux USB drivers of downstream
> USB bus activity when connecting a high-speed or superSpeed device via the
> Microchip USB491x hub. This delay is due to the fixed bInterval value of
> 12 in the silicon of the Microchip USB491x hub.
>
> Microchip requested to ignore the device descriptor and decrease that
> value to 9 as it was too late to modify that in silicon.
>
> This patch speeds up the USB enummeration process that helps to pass
> Apple Carplay certifications and improve the User experience when utilizing
> the USB device via Microchip Multihost USB491x Hub.
>
> A new hub quirk HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL speeds up
> the notification process for Microchip USB491x hub by limiting
> the maximum bInterval value to 9.
>
> Signed-off-by: Hardik Gajjar <[email protected]>
> ---
> changes since version 1:
> - Move implementation from config.c and quirk.c to hub.c as this is hub
> specific changes.
> - Improve commit message.
> - Link to v1 - https://lore.kernel.org/all/[email protected]/
> ---
> drivers/usb/core/hub.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index b4584a0cd484..3d26d942fcae 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -47,12 +47,18 @@
> #define USB_VENDOR_TEXAS_INSTRUMENTS 0x0451
> #define USB_PRODUCT_TUSB8041_USB3 0x8140
> #define USB_PRODUCT_TUSB8041_USB2 0x8142
> +#define USB_VENDOR_MICROCHIP 0x0424
> +#define USB_PRODUCT_USB4913 0x4913
> +#define USB_PRODUCT_USB4914 0x4914
> +#define USB_PRODUCT_USB4915 0x4915
> #define HUB_QUIRK_CHECK_PORT_AUTOSUSPEND 0x01
> #define HUB_QUIRK_DISABLE_AUTOSUSPEND 0x02
> +#define HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL 0x08
Why not use 0x04, the next available bit?
>
> #define USB_TP_TRANSMISSION_DELAY 40 /* ns */
> #define USB_TP_TRANSMISSION_DELAY_MAX 65535 /* ns */
> #define USB_PING_RESPONSE_TIME 400 /* ns */
> +#define USB_REDUCE_FRAME_INTR_BINTERVAL 9
>
> /* Protect struct usb_device->state and ->children members
> * Note: Both are also protected by ->dev.sem, except that ->state can
> @@ -1927,6 +1933,12 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
> usb_autopm_get_interface_no_resume(intf);
> }
>
> + if ((id->driver_info & HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL) &&
> + desc->endpoint[0].desc.bInterval > USB_REDUCE_FRAME_INTR_BINTERVAL) {
> + desc->endpoint[0].desc.bInterval =
> + USB_REDUCE_FRAME_INTR_BINTERVAL;
As I mentioned in an earlier email, you need to do:
/* Tell the HCD about the interrupt ep's new bInterval */
usb_set_interface(hdev, 0, 0);
here. Everything else looks okay (and much better than before).
Alan Stern
> + }
> +
> if (hub_configure(hub, &desc->endpoint[0].desc) >= 0) {
> onboard_hub_create_pdevs(hdev, &hub->onboard_hub_devs);
>
> @@ -5918,6 +5930,21 @@ static const struct usb_device_id hub_id_table[] = {
> .idVendor = USB_VENDOR_TEXAS_INSTRUMENTS,
> .idProduct = USB_PRODUCT_TUSB8041_USB3,
> .driver_info = HUB_QUIRK_DISABLE_AUTOSUSPEND},
> + { .match_flags = USB_DEVICE_ID_MATCH_VENDOR
> + | USB_DEVICE_ID_MATCH_PRODUCT,
> + .idVendor = USB_VENDOR_MICROCHIP,
> + .idProduct = USB_PRODUCT_USB4913,
> + .driver_info = HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL},
> + { .match_flags = USB_DEVICE_ID_MATCH_VENDOR
> + | USB_DEVICE_ID_MATCH_PRODUCT,
> + .idVendor = USB_VENDOR_MICROCHIP,
> + .idProduct = USB_PRODUCT_USB4914,
> + .driver_info = HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL},
> + { .match_flags = USB_DEVICE_ID_MATCH_VENDOR
> + | USB_DEVICE_ID_MATCH_PRODUCT,
> + .idVendor = USB_VENDOR_MICROCHIP,
> + .idProduct = USB_PRODUCT_USB4915,
> + .driver_info = HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL},
> { .match_flags = USB_DEVICE_ID_MATCH_DEV_CLASS,
> .bDeviceClass = USB_CLASS_HUB},
> { .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS,
> --
> 2.17.1
>