2022-06-28 02:57:05

by Neal Liu

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

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 <[email protected]>
---
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

2022-06-28 15:14:27

by Alan Stern

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

On Tue, Jun 28, 2022 at 10:14:36AM +0800, Neal Liu wrote:
> 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 <[email protected]>
> ---

Reviewed-by: Alan Stern <[email protected]>

> 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
>