[PATCH 2/2] USB: storage: ums-realtek: Enable auto-delink optionally

[Kai-Heng Feng <kai.heng.feng@canonical.com>]

Auto-delink requires writing special registers to ums-realtek device.
Unconditionally enable auto-delink may break newer devices.

So only enable auto-delink by default for the original three IDs,
0x0138, 0x0158 and 0x0159.

Realtek is working on a patch to properly support auto-delink for other
IDs.

BugLink: https://bugs.launchpad.net/bugs/1838886
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/usb/storage/realtek_cr.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/storage/realtek_cr.c b/drivers/usb/storage/realtek_cr.c
index 4d86cfcc0b40..376f41d0cbc3 100644
--- a/drivers/usb/storage/realtek_cr.c
+++ b/drivers/usb/storage/realtek_cr.c
@@ -36,6 +36,10 @@ MODULE_DESCRIPTION("Driver for Realtek USB Card Reader");
 MODULE_AUTHOR("wwang <wei_wang@realsil.com.cn>");
 MODULE_LICENSE("GPL");
 
+static int auto_delink_enable = -1;
+module_param(auto_delink_enable, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(auto_delink_enable, "enable auto delink (-1=auto [default], 0=disable, 1=enable)");
+
 static int auto_delink_mode = 1;
 module_param(auto_delink_mode, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(auto_delink_mode, "auto delink mode (0=firmware, 1=software [default])");
@@ -996,12 +1000,22 @@ static int init_realtek_cr(struct us_data *us)
 			goto INIT_FAIL;
 	}
 
-	if (CHECK_FW_VER(chip, 0x5888) || CHECK_FW_VER(chip, 0x5889) ||
-	    CHECK_FW_VER(chip, 0x5901))
-		SET_AUTO_DELINK(chip);
-	if (STATUS_LEN(chip) == 16) {
-		if (SUPPORT_AUTO_DELINK(chip))
+	if (auto_delink_enable == -1) {
+		if (CHECK_PID(chip, 0x0138) || CHECK_PID(chip, 0x0158) ||
+		    CHECK_PID(chip, 0x0159))
+			auto_delink_enable = 1;
+		else
+			auto_delink_enable = 0;
+	}
+
+	if (auto_delink_enable) {
+		if (CHECK_FW_VER(chip, 0x5888) || CHECK_FW_VER(chip, 0x5889) ||
+				CHECK_FW_VER(chip, 0x5901))
 			SET_AUTO_DELINK(chip);
+		if (STATUS_LEN(chip) == 16) {
+			if (SUPPORT_AUTO_DELINK(chip))
+				SET_AUTO_DELINK(chip);
+		}
 	}
 #ifdef CONFIG_REALTEK_AUTOPM
 	if (ss_en)
-- 
2.17.1