Hi, Jim Lin <jilin@xxxxxxxxxx> writes: > On 2016年04月28日 20:21, Felipe Balbi wrote: >>> >>> I also attach git log of system/core/adb/usb_linux_client.cpp of Android >>> N for your reference. >>> " >>> Author: Badhri Jagan Sridharan <Badhri@xxxxxxxxxx> >>> Date: Mon Oct 5 13:04:03 2015 -0700 >>> >>> adbd: Add os descriptor support for adb. >>> >>> Eventhough windows does not rely on extended os >>> descriptor for adbd, when android usb device is >>> configures as a composite device such as mtp+adb, >>> windows discards the extended os descriptor even >>> if one of the USB function fails to send >>> the extended compat descriptor. This results in automatic >>> install of MTP driverto fail when Android device is in >>> "File Transfer" mode with adb enabled. >>> >>> https://msdn.microsoft.com/en-us/library/windows/hardware/gg463179.aspx >>> " >> Okay, cool. Can you check that you're limitting your controller's speed >> to high-speed ? >> > Let's focus on original patch. > Could you help to explain why we need below d->Reserved1 checking? > Now the question is that > > https://msdn.microsoft.com/en-us/library/windows/hardware/gg463179.aspx > > Page 7 of OS_Desc_CompatID.doc > defines reserved field to be 1 and > below code will think that os_desc is invalid because d->Reserved1 is 1. > > > In f_fs.c > " > static int __ffs_data_do_os_desc(enum ffs_os_desc_type type, > struct usb_os_desc_header *h, void *data, > unsigned len, void *priv) > { > struct ffs_data *ffs = priv; > u8 length; > > ENTER(); > > switch (type) { > case FFS_OS_DESC_EXT_COMPAT: { > struct usb_ext_compat_desc *d = data; > int i; > > if (len < sizeof(*d) || > d->bFirstInterfaceNumber >= ffs->interfaces_count || > d->Reserved1) > return -EINVAL; > " that's fine, but this is only failing because something else is returning the wrong set of descriptors (SS vs HS). That's the bug we want to fix, not work around it. -- balbi
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