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 <hgajjar@xxxxxxxxxxxxxx> --- 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/20231123081948.58776-1-hgajjar@xxxxxxxxxxxxxx/ changes since version 2: - Call usb_set_interface after updating the bInterval to Tell the HCD about modification - Link to v2 - https://lore.kernel.org/all/20231130084855.119937-1-hgajjar@xxxxxxxxxxxxxx/ --- 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..b5ac29c5f016 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 +1933,14 @@ 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; + /* Tell the HCD about the interrupt ep's new bInterval */ + usb_set_interface(hdev, 0, 0); + } + if (hub_configure(hub, &desc->endpoint[0].desc) >= 0) { onboard_hub_create_pdevs(hdev, &hub->onboard_hub_devs); @@ -5918,6 +5932,21 @@ 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
