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hwstub: fix long transfers failing because of control xfer size of libusb

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libusb limits control transfer sizes to 4k, see diff for details.

Change-Id: Id2e638010274009ea641d06e9040a8b9ab9d54a9
This commit is contained in:
Amaury Pouly 2017-01-17 11:32:50 +01:00
parent 24c208336c
commit eadba57d53
2 changed files with 23 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

4
utils/hwstub/include/hwstub_usb.hpp
View file

@ -101,6 +101,10 @@ public:
void set_timeout(std::chrono::milliseconds ms);
protected:
/* return the maximum size of a libusb control transfer, this is a "known"
* limitation that is completely undocumented (sigh) and applies at least
* to linux and windows hosts */
size_t max_libusb_control_xfer_size() const;
/* interpret libusb error: >=0 means SUCCESS, others are treated as errors,
* LIBUSB_ERROR_NO_DEVICE is treated as DISCONNECTED */
error interpret_libusb_error(int err);

21
utils/hwstub/lib/hwstub_usb.cpp
View file

@ -245,6 +245,15 @@ handle::~handle()
libusb_close(m_handle);
}
size_t handle::max_libusb_control_xfer_size() const
{
/* on Linux and Windows, libusb limits control transfers to 4k, this is not
* documented anywhere except in the source code, see libusb/os/linux_usbfs.h
* for MAX_CTRL_BUFFER_LENGTH. Obviously they didn't put it in the system
* header files... */
return 4096;
}
error handle::interpret_libusb_error(int err)
{
if(err >= 0)
@ -252,7 +261,10 @@ error handle::interpret_libusb_error(int err)
if(err == LIBUSB_ERROR_NO_DEVICE)
return error::DISCONNECTED;
else
{
get_device()->get_context()->debug() << "[usb::handle] libusb error: " << err << "\n";
return error::USB_ERROR;
}
}
error handle::interpret_libusb_error(int err, size_t expected_val)
@ -332,7 +344,10 @@ rb_handle::~rb_handle()
size_t rb_handle::get_buffer_size()
{
return m_buf_size;
/* We return slightly less because the usb protocol involves sending a header
* followed by the data, so it reduces the actual buffer size by the size
* of the header. To be safe, allow for a 128 bytes header. */
return std::min(m_buf_size, max_libusb_control_xfer_size()) - 128;
}
error rb_handle::status() const
@ -543,7 +558,9 @@ error jz_handle::probe()
m_desc_layout.dStackStart = 0; /* As far as I can tell, the ROM uses no stack */
m_desc_layout.dStackSize = 0;
m_desc_layout.dBufferStart = 0x080000000;
m_desc_layout.dBufferSize = 0x4000;
/* max buffer size: leave some space for header so that header + data doesn't
* hit the limit */
m_desc_layout.dBufferSize = max_libusb_control_xfer_size() - 128;
m_desc_target.bLength = sizeof(m_desc_target);
m_desc_target.bDescriptorType = HWSTUB_DT_TARGET;