Patch "usb: hub: Add quirk to decrease IN-ep poll interval for Microchip USB491x hub" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    usb: hub: Add quirk to decrease IN-ep poll interval for Microchip USB491x hub

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-hub-add-quirk-to-decrease-in-ep-poll-interval-fo.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fd43b2db088864c268a24e4daa067a9131a92631
Author: Hardik Gajjar <hgajjar@xxxxxxxxxxxxxx>
Date:   Tue Dec 5 19:18:29 2023 +0100

    usb: hub: Add quirk to decrease IN-ep poll interval for Microchip USB491x hub
    
    [ Upstream commit 855d75cf8311fee156fabb5639bb53757ca83dd4 ]
    
    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>
    Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20231205181829.127353-2-hgajjar@xxxxxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 9163fd5af046..4f181110d00d 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	BIT(0)
 #define HUB_QUIRK_DISABLE_AUTOSUSPEND		BIT(1)
+#define HUB_QUIRK_REDUCE_FRAME_INTR_BINTERVAL	BIT(2)
 
 #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
@@ -1904,6 +1910,14 @@ 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);
 
@@ -5885,6 +5899,21 @@ 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,




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