linux-kernel - [RFC v5 6/6] usb: dwc3: gadget: Ensure enough TXFIFO space for USB configuration

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Date:   Fri, 28 Aug 2020 22:58:46 -0700
From:   Wesley Cheng <wcheng@...eaurora.org>
To:     robh+dt@...nel.org, bjorn.andersson@...aro.org, balbi@...nel.org,
        gregkh@...uxfoundation.org, agross@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-usb@...r.kernel.org,
        jackp@...eaurora.org, Wesley Cheng <wcheng@...eaurora.org>
Subject: [RFC v5 6/6] usb: dwc3: gadget: Ensure enough TXFIFO space for USB configuration

If TXFIFO resizing is enabled, then based on if endpoint bursting is
required or not, a larger amount of FIFO space is benefical.  Sometimes
a particular interface can take all the available FIFO space, leading
to other interfaces not functioning properly.  This callback ensures that
the minimum fifo requirements, a single fifo per endpoint, can be met,
otherwise the configuration binding will fail.  This will be based on the
maximum number of eps existing in all configurations.

Signed-off-by: Wesley Cheng <wcheng@...eaurora.org>
---
 drivers/usb/dwc3/core.h   |  1 +
 drivers/usb/dwc3/gadget.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index e85c1ec70cc3..0559b0a82c4d 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1249,6 +1249,7 @@ struct dwc3 {
 	u16			imod_interval;
 	int			last_fifo_depth;
 	int			num_ep_resized;
+	int			max_cfg_eps;
 };
 
 #define INCRX_BURST_MODE 0
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 53e5220f9893..e8f7ea560920 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2411,6 +2411,7 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 
 out:
 	dwc->gadget_driver	= NULL;
+	dwc->max_cfg_eps = 0;
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	free_irq(dwc->irq_gadget, dwc->ev_buf);
@@ -2518,6 +2519,39 @@ static void dwc3_gadget_set_speed(struct usb_gadget *g,
 	spin_unlock_irqrestore(&dwc->lock, flags);
 }
 
+static int dwc3_gadget_check_config(struct usb_gadget *g, unsigned long ep_map)
+{
+	struct dwc3 *dwc = gadget_to_dwc(g);
+	unsigned long in_ep_map;
+	int fifo_size = 0;
+	int ram1_depth;
+	int ep_num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	/* Only interested in the IN endpoints */
+	in_ep_map = ep_map >> 16;
+	ep_num = hweight_long(in_ep_map);
+
+	if (ep_num <= dwc->max_cfg_eps)
+		return 0;
+
+	/* Update the max number of eps in the composition */
+	dwc->max_cfg_eps = ep_num;
+
+	fifo_size = dwc3_gadget_calc_tx_fifo_size(dwc, dwc->max_cfg_eps);
+	/* Based on the equation, increment by one for every ep */
+	fifo_size += dwc->max_cfg_eps;
+
+	/* Check if we can fit a single fifo per endpoint */
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	if (fifo_size > ram1_depth)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,
@@ -2527,6 +2561,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_stop		= dwc3_gadget_stop,
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
+	.check_config		= dwc3_gadget_check_config,
 };
 
 /* -------------------------------------------------------------------------- */
-- 
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