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FAILED: patch "[PATCH] usb: dwc3: gadget: Fix IN endpoint max packet size allocation" failed to apply to 5.15-stable tree

PATCH [email protected] 1 participant 1 message Jun 20, 2022

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Stable branch USB DesignWare USB3 DRD IP driver
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The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9c1e916960c1192e746bf615e4dae25423473a64 Mon Sep 17 00:00:00 2001
From: Wesley Cheng <[email protected]>
Date: Mon, 23 May 2022 14:39:48 -0700
Subject: [PATCH] usb: dwc3: gadget: Fix IN endpoint max packet size allocation

The current logic to assign the max packet limit for IN endpoints attempts to take the default HW value and apply the optimal endpoint settings based on it. However, if the default value reports a TxFIFO size large enough for only one max packet, it will divide the value and assign a smaller ep max packet limit.

For example, if the default TxFIFO size fits 1024B, current logic will assign 1024/3 = 341B to ep max packet size. If function drivers attempt to request for an endpoint with a wMaxPacketSize of 1024B (SS BULK max packet size) then it will fail, as the gadget is unable to find an endpoint which can fit the requested size.

Functionally, if the TxFIFO has enough space to fit one max packet, it will be sufficient, at least when initializing the endpoints.

Fixes d94ea5319813 ("usb: dwc3: gadget: Properly set maxpacket limit")
Cc stable <[email protected]>
Signed-off-by Wesley Cheng <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Greg Kroah-Hartman <[email protected]>
drivers/usb/dwc3/gadget.c +15 -11
index 00427d108ab9..8716bece1072 100644
@@ -2976,6 +2976,7 @@ static int dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep)
 	struct dwc3 *dwc = dep->dwc;
 	u32 mdwidth;
 	int size;
+	int maxpacket;
 
 	mdwidth = dwc3_mdwidth(dwc);
 

@@ -2988,21 +2989,24 @@ static int dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep)
 	else
 		size = DWC31_GTXFIFOSIZ_TXFDEP(size);
 
-	/* FIFO Depth is in MDWDITH bytes. Multiply */
-	size *= mdwidth;
-
 	/*
-	 * To meet performance requirement, a minimum TxFIFO size of 3x
-	 * MaxPacketSize is recommended for endpoints that support burst and a
-	 * minimum TxFIFO size of 2x MaxPacketSize for endpoints that don't
-	 * support burst. Use those numbers and we can calculate the max packet
-	 * limit as below.
+	 * maxpacket size is determined as part of the following, after assuming
+	 * a mult value of one maxpacket:
+	 * DWC3 revision 280A and prior:
+	 * fifo_size = mult * (max_packet / mdwidth) + 1;
+	 * maxpacket = mdwidth * (fifo_size - 1);
+	 *
+	 * DWC3 revision 290A and onwards:
+	 * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
+	 * maxpacket = mdwidth * ((fifo_size - 1) - 1) - mdwidth;
 	 */
-	if (dwc->maximum_speed >= USB_SPEED_SUPER)
-		size /= 3;
+	if (DWC3_VER_IS_PRIOR(DWC3, 290A))
+		maxpacket = mdwidth * (size - 1);
 	else
-		size /= 2;
+		maxpacket = mdwidth * ((size - 1) - 1) - mdwidth;
 
+	/* Functionally, space for one max packet is sufficient */
+	size = min_t(int, maxpacket, 1024);
 	usb_ep_set_maxpacket_limit(&dep->endpoint, size);
 
 	dep->endpoint.max_streams = 16;