2010-07-01 09:18:20

by Michal Nazarewicz

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Subject: [PATCH] USB: gadget: mass storage: use proper device class in device desc

This patch changes the bDeviceClass, bDeviceSubClass, bDeviceProtocol
to match the real class and protocol instead of leaving it as per
interface.

Signed-off-by: Michal Nazarewicz <[email protected]>
Cc: Kyungmin Park <[email protected]>
---
Hello Alan,

Each time I see the device descriptor of the File Storage Gadget
I wonder if it shouldn't be set to the real value rather then leaving
it as per interface.

Is there a reason to leave it as per interface? Will chenging it to
the real value change anything?

I checked my pendrive and an IDE<->USB adapter they as well use a per
interface class but maybe it'll be better to use proper call any way?

drivers/usb/gadget/file_storage.c | 6 +++++-
drivers/usb/gadget/mass_storage.c | 4 +++-
2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index d57c09f..1f76ea0 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -544,7 +544,9 @@ device_desc = {
.bDescriptorType = USB_DT_DEVICE,

.bcdUSB = cpu_to_le16(0x0200),
- .bDeviceClass = USB_CLASS_PER_INTERFACE,
+ .bDeviceClass = USB_CLASS_MASS_STORAGE,
+ .bDeviceSubClass = USB_SC_SCSI, /* Adjusted during fsg_bind() */
+ .bDeviceProtocol = USB_PR_BULK, /* Adjusted during fsg_bind() */

/* The next three values can be overridden by module parameters */
.idVendor = cpu_to_le16(FSG_VENDOR_ID),
@@ -3450,7 +3452,9 @@ static int __ref fsg_bind(struct usb_gadget *gadget)
i = (transport_is_cbi() ? 3 : 2); // Number of endpoints
fsg_intf_desc.bNumEndpoints = i;
fsg_intf_desc.bInterfaceSubClass = mod_data.protocol_type;
+ device_desc.bDeviceSubClass = mod_data.protocol_type;
fsg_intf_desc.bInterfaceProtocol = mod_data.transport_type;
+ device_desc.bDeviceProtocol = mod_data.transport_type;
fsg_fs_function[i + FSG_FS_FUNCTION_PRE_EP_ENTRIES] = NULL;

if (gadget_is_dualspeed(gadget)) {
diff --git a/drivers/usb/gadget/mass_storage.c b/drivers/usb/gadget/mass_storage.c
index 585f255..59054a4 100644
--- a/drivers/usb/gadget/mass_storage.c
+++ b/drivers/usb/gadget/mass_storage.c
@@ -70,7 +70,9 @@ static struct usb_device_descriptor msg_device_desc = {
.bDescriptorType = USB_DT_DEVICE,

.bcdUSB = cpu_to_le16(0x0200),
- .bDeviceClass = USB_CLASS_PER_INTERFACE,
+ .bDeviceClass = USB_CLASS_MASS_STORAGE,
+ .bDeviceSubClass = USB_SC_SCSI,
+ .bDeviceProtocol = USB_PR_BULK,

/* Vendor and product id can be overridden by module parameters. */
.idVendor = cpu_to_le16(FSG_VENDOR_ID),
--
1.7.1


2010-07-01 10:09:51

by David Brownell

[permalink] [raw]
Subject: Re: [PATCH] USB: gadget: mass storage: use proper device class in device desc



--- On Thu, 7/1/10, Michal Nazarewicz <[email protected]> wrote:

> to match the real class and protocol instead of leaving it
> as per
> interface.

It works now though ... why change it,
and risk causing breakage??

>
>
> Each time I see the device descriptor of the File Storage
> Gadget
> I wonder if it shouldn't be set to the real value rather
> then leaving
> it as per interface.
>
> Is there a reason to leave it as per interface?? Will
> chenging it to
> the real value change anything?
>
> I checked my pendrive and an IDE<->USB adapter they
> as well use a per
> interface class ...

2010-07-01 10:14:18

by Michal Nazarewicz

[permalink] [raw]
Subject: Re: [PATCH] USB: gadget: mass storage: use proper device class in device desc

On Thu, 01 Jul 2010 12:09:48 +0200, David Brownell <[email protected]> wrote:
> It works now though ... why change it,
> and risk causing breakage??

OK.

--
Best regards, _ _
| Humble Liege of Serenely Enlightened Majesty of o' \,=./ `o
| Computer Science, Michał "mina86" Nazarewicz (o o)
+----[mina86*mina86.com]---[mina86*jabber.org]----ooO--(_)--Ooo--

2010-07-01 14:09:43

by Alan Stern

[permalink] [raw]
Subject: Re: [PATCH] USB: gadget: mass storage: use proper device class in device desc

On Thu, 1 Jul 2010, Michal Nazarewicz wrote:

> Hello Alan,
>
> Each time I see the device descriptor of the File Storage Gadget
> I wonder if it shouldn't be set to the real value rather then leaving
> it as per interface.

It should not be changed.

> Is there a reason to leave it as per interface?

See Table 4.1 in the USB Mass Storage Bulk-Only Transport
specification and Table 3.1 in the CBI Transport specification.

> Will chenging it to
> the real value change anything?

You mean will it hurt anything? I don't know; I have never tried it.

> I checked my pendrive and an IDE<->USB adapter they as well use a per
> interface class but maybe it'll be better to use proper call any way?

No. And it's not a proper call -- it's not even the proper descriptor
valu. So NAK on this patch.

Alan Stern

2010-07-01 14:25:31

by Michal Nazarewicz

[permalink] [raw]
Subject: Re: [PATCH] USB: gadget: mass storage: use proper device class in device desc

> On Thu, 1 Jul 2010, Michal Nazarewicz wrote:
>> Each time I see the device descriptor of the File Storage Gadget
>> I wonder if it shouldn't be set to the real value rather then leaving
>> it as per interface.

On Thu, 01 Jul 2010 16:09:39 +0200, Alan Stern <[email protected]> wrote:
> It should not be changed.

>> Is there a reason to leave it as per interface?

> See Table 4.1 in the USB Mass Storage Bulk-Only Transport
> specification and Table 3.1 in the CBI Transport specification.

Ha! Thanks for clarification. Will have to look more careful through
the specs next time.

--
Best regards, _ _
| Humble Liege of Serenely Enlightened Majesty of o' \,=./ `o
| Computer Science, Michał "mina86" Nazarewicz (o o)
+----[mina86*mina86.com]---[mina86*jabber.org]----ooO--(_)--Ooo--