linux-kernel - [PATCH 06/15] usb: dwc2: Clear fifo

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Date:   Thu, 15 Apr 2021 09:40:08 +0400
From:   Artur Petrosyan <Arthur.Petrosyan@...opsys.com>
To:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     John Youn <John.Youn@...opsys.com>,
        Artur Petrosyan <Arthur.Petrosyan@...opsys.com>,
        Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
Subject: [PATCH 06/15] usb: dwc2: Clear fifo_map when resetting core.

Switching from device mode to host mode by disconnecting
device cable core enters and exits form hibernation.
However, the fifo map remains not cleared. It results
to a WARNING (WARNING: CPU: 5 PID: 0 at drivers/usb/dwc2/
gadget.c:307 dwc2_hsotg_init_fifo+0x12/0x152 [dwc2])
if in host mode we disconnect the micro a to b host
cable. Because core reset occurs.

To avoid the WARNING, fifo_map should be cleared
in dwc2_core_reset() function by taking into account configs.
fifo_map must be cleared only if driver is configured in
"CONFIG_USB_DWC2_PERIPHERAL" or "CONFIG_USB_DWC2_DUAL_ROLE"
mode.

- Added "static inline void dwc2_clear_fifo_map()" helper
function to clear fifo_map with peripheral or dual role mode.

- Added a dummy version of "dwc2_clear_fifo_map()" helper
for host-only mode.

Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@...opsys.com>
Acked-by: Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
---
 drivers/usb/dwc2/core.c | 16 ++++++++++++++++
 drivers/usb/dwc2/core.h |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index cb65f7f60573..eccd96fa164e 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -470,6 +470,22 @@ int dwc2_core_reset(struct dwc2_hsotg *hsotg, bool skip_wait)
 		dwc2_writel(hsotg, greset, GRSTCTL);
 	}
 
+	/*
+	 * Switching from device mode to host mode by disconnecting
+	 * device cable core enters and exits form hibernation.
+	 * However, the fifo map remains not cleared. It results
+	 * to a WARNING (WARNING: CPU: 5 PID: 0 at drivers/usb/dwc2/
+	 * gadget.c:307 dwc2_hsotg_init_fifo+0x12/0x152 [dwc2])
+	 * if in host mode we disconnect the micro a to b host
+	 * cable. Because core reset occurs.
+	 * To avoid the WARNING, fifo_map should be cleared
+	 * in dwc2_core_reset() function by taking into account configs.
+	 * fifo_map must be cleared only if driver is configured in
+	 * "CONFIG_USB_DWC2_PERIPHERAL" or "CONFIG_USB_DWC2_DUAL_ROLE"
+	 * mode.
+	 */
+	dwc2_clear_fifo_map(hsotg);
+
 	/* Wait for AHB master IDLE state */
 	if (dwc2_hsotg_wait_bit_set(hsotg, GRSTCTL, GRSTCTL_AHBIDLE, 10000)) {
 		dev_warn(hsotg->dev, "%s: HANG! AHB Idle timeout GRSTCTL GRSTCTL_AHBIDLE\n",
diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 8c12b3061f7f..e1f432095565 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -1423,6 +1423,8 @@ int dwc2_hsotg_tx_fifo_total_depth(struct dwc2_hsotg *hsotg);
 int dwc2_hsotg_tx_fifo_average_depth(struct dwc2_hsotg *hsotg);
 void dwc2_gadget_init_lpm(struct dwc2_hsotg *hsotg);
 void dwc2_gadget_program_ref_clk(struct dwc2_hsotg *hsotg);
+static inline void dwc2_clear_fifo_map(struct dwc2_hsotg *hsotg)
+{ hsotg->fifo_map = 0; }
 #else
 static inline int dwc2_hsotg_remove(struct dwc2_hsotg *dwc2)
 { return 0; }
@@ -1467,6 +1469,7 @@ static inline int dwc2_hsotg_tx_fifo_average_depth(struct dwc2_hsotg *hsotg)
 { return 0; }
 static inline void dwc2_gadget_init_lpm(struct dwc2_hsotg *hsotg) {}
 static inline void dwc2_gadget_program_ref_clk(struct dwc2_hsotg *hsotg) {}
+static inline void dwc2_clear_fifo_map(struct dwc2_hsotg *hsotg) {}
 #endif
 
 #if IS_ENABLED(CONFIG_USB_DWC2_HOST) || IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)
-- 
2.25.1