[PATCH v3] usb: gadget: f_mass_storage: Make CD-ROM emulation works with Windows OS

[Neal Liu]

Add read TOC with format 1 to support CD-ROM emulation with
Windows OS.
This patch is tested on Windows OS Server 2019.

Fixes: 89ada0fe669a ("usb: gadget: f_mass_storage: Make CD-ROM emulation work
with Mac OS-X")
Signed-off-by: Neal Liu <neal_liu@xxxxxxxxxxxxxx>
---
v3:
- ignore start_track value with format 1
- add fixes tags
- revise comments properly

v2:
- revise comments

 drivers/usb/gadget/function/f_mass_storage.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c
index 3a77bca0ebe1..e884f295504f 100644
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -1192,13 +1192,14 @@ static int do_read_toc(struct fsg_common *common, struct fsg_buffhd *bh)
 	u8		format;
 	int		i, len;
 
+	format = common->cmnd[2] & 0xf;
+
 	if ((common->cmnd[1] & ~0x02) != 0 ||	/* Mask away MSF */
-			start_track > 1) {
+			(start_track > 1 && format != 0x1)) {
 		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 		return -EINVAL;
 	}
 
-	format = common->cmnd[2] & 0xf;
 	/*
 	 * Check if CDB is old style SFF-8020i
 	 * i.e. format is in 2 MSBs of byte 9
@@ -1208,8 +1209,8 @@ static int do_read_toc(struct fsg_common *common, struct fsg_buffhd *bh)
 		format = (common->cmnd[9] >> 6) & 0x3;
 
 	switch (format) {
-	case 0:
-		/* Formatted TOC */
+	case 0:	/* Formatted TOC */
+	case 1:	/* Multi-session info */
 		len = 4 + 2*8;		/* 4 byte header + 2 descriptors */
 		memset(buf, 0, len);
 		buf[1] = len - 2;	/* TOC Length excludes length field */
@@ -1250,7 +1251,7 @@ static int do_read_toc(struct fsg_common *common, struct fsg_buffhd *bh)
 		return len;
 
 	default:
-		/* Multi-session, PMA, ATIP, CD-TEXT not supported/required */
+		/* PMA, ATIP, CD-TEXT not supported/required */
 		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 		return -EINVAL;
 	}
-- 
2.25.1