[PATCH] usb: host: xhci-rcar: Don't reload firmware after the completion

[PATCH] usb: host: xhci-rcar: Don't reload firmware after the completion

[Yoshihiro Shimoda]

According to the datasheet, "Upon the completion of FW Download,
there is no need to write or reload FW.". Otherwise, it's possible
to cause unexpected behaviors. So, adds such a condition.

Fixes: 4ac8918f3a73 ("usb: host: xhci-plat: add support for the R-Car H2 and M2 xHCI controllers")
Cc: stable@vger.kernel.org # v3.17+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 drivers/usb/host/xhci-rcar.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/usb/host/xhci-rcar.c b/drivers/usb/host/xhci-rcar.c
index 1bc4fe7b8c75..9888ba7d85b6 100644
--- a/drivers/usb/host/xhci-rcar.c
+++ b/drivers/usb/host/xhci-rcar.c
@@ -134,6 +134,13 @@ static int xhci_rcar_download_firmware(struct usb_hcd *hcd)
 	const struct soc_device_attribute *attr;
 	const char *firmware_name;
 
+	/*
+	 * According to the datasheet, "Upon the completion of FW Download,
+	 * there is no need to write or reload FW".
+	 */
+	if (readl(regs + RCAR_USB3_DL_CTRL) & RCAR_USB3_DL_CTRL_FW_SUCCESS)
+		return 0;
+
 	attr = soc_device_match(rcar_quirks_match);
 	if (attr)
 		quirks = (uintptr_t)attr->data;
-- 
2.25.1