Patch "usb: dwc3: gadget: Skip resizing EP's TX FIFO if already resized" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    usb: dwc3: gadget: Skip resizing EP's TX FIFO if already resized

to the 5.15-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-dwc3-gadget-skip-resizing-ep-s-tx-fifo-if-alread.patch
and it can be found in the queue-5.15 subdirectory.

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



commit a01514383948cd7c7cf9c7ea62c9f41db938fcd2
Author: Jack Pham <jackp@xxxxxxxxxxxxxx>
Date:   Thu Oct 21 11:01:28 2021 -0700

    usb: dwc3: gadget: Skip resizing EP's TX FIFO if already resized
    
    [ Upstream commit 876a75cb520f5869533a30a6ca01545ec817b7a0 ]
    
    Some functions may dynamically enable and disable their endpoints
    regularly throughout their operation, particularly when Set Interface
    is employed to switch between Alternate Settings.  For instance the
    UAC2 function has its respective endpoints for playback & capture
    associated with AltSetting 1, in which case those endpoints would not
    get enabled until the host activates the AltSetting.  And they
    conversely become disabled when the interfaces' AltSetting 0 is
    chosen.
    
    With the DWC3 FIFO resizing algorithm recently added, every
    usb_ep_enable() call results in a call to resize that EP's TXFIFO,
    but if the same endpoint is enabled again and again, this incorrectly
    leads to FIFO RAM allocation exhaustion as the mechanism did not
    account for the possibility that endpoints can be re-enabled many
    times.
    
    Example log splat:
    
            dwc3 a600000.dwc3: Fifosize(3717) > RAM size(3462) ep3in depth:217973127
            configfs-gadget gadget: u_audio_start_capture:521 Error!
            dwc3 a600000.dwc3: request 000000000be13e18 was not queued to ep3in
    
    Add another bit DWC3_EP_TXFIFO_RESIZED to dep->flags to keep track of
    whether an EP had already been resized in the current configuration.
    If so, bail out of dwc3_gadget_resize_tx_fifos() to avoid the
    calculation error resulting from accumulating the EP's FIFO depth
    repeatedly.  This flag is retained across multiple ep_disable() and
    ep_enable() calls and is cleared when GTXFIFOSIZn is reset in
    dwc3_gadget_clear_tx_fifos() upon receiving the next Set Config.
    
    Fixes: 9f607a309fbe9 ("usb: dwc3: Resize TX FIFOs to meet EP bursting requirements")
    Reviewed-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
    Signed-off-by: Jack Pham <jackp@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20211021180129.27938-1-jackp@xxxxxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 5612bfdf37da9..0c100901a7845 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -723,6 +723,7 @@ struct dwc3_ep {
 #define DWC3_EP_FORCE_RESTART_STREAM	BIT(9)
 #define DWC3_EP_FIRST_STREAM_PRIMED	BIT(10)
 #define DWC3_EP_PENDING_CLEAR_STALL	BIT(11)
+#define DWC3_EP_TXFIFO_RESIZED		BIT(12)
 
 	/* This last one is specific to EP0 */
 #define DWC3_EP0_DIR_IN		BIT(31)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 4519d06c9ca2b..ed97e47d32613 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -702,6 +702,7 @@ void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
 				   DWC31_GTXFIFOSIZ_TXFRAMNUM;
 
 		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1), size);
+		dep->flags &= ~DWC3_EP_TXFIFO_RESIZED;
 	}
 	dwc->num_ep_resized = 0;
 }
@@ -747,6 +748,10 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
 	if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
 		return 0;
 
+	/* bail if already resized */
+	if (dep->flags & DWC3_EP_TXFIFO_RESIZED)
+		return 0;
+
 	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
 
 	if ((dep->endpoint.maxburst > 1 &&
@@ -807,6 +812,7 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
 	}
 
 	dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
+	dep->flags |= DWC3_EP_TXFIFO_RESIZED;
 	dwc->num_ep_resized++;
 
 	return 0;
@@ -995,7 +1001,7 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
 
 	dep->stream_capable = false;
 	dep->type = 0;
-	dep->flags = 0;
+	dep->flags &= DWC3_EP_TXFIFO_RESIZED;
 
 	return 0;
 }