[PATCH 5.4 32/37] usb: host: xhci-rcar: Dont reload firmware after the completion

[Greg Kroah-Hartman]

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

commit 57f3ffdc11143f56f1314972fe86fe17a0dcde85 upstream.

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@xxxxxxxxxxxxxxx # v3.17+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210827063227.81990-1-yoshihiro.shimoda.uh@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/host/xhci-rcar.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/usb/host/xhci-rcar.c
+++ b/drivers/usb/host/xhci-rcar.c
@@ -134,6 +134,13 @@ static int xhci_rcar_download_firmware(s
 	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;