On Tue, Jun 05, 2018 at 04:54:17PM +0800, gengdongjiu wrote: > > > On 2018/6/5 16:40, Greg KH wrote: > > On Wed, Jun 06, 2018 at 12:35:00AM +0800, Dongjiu Geng wrote: > >> Initialize the 'err' variate to remove the build warning, > >> the warning is shown as below: > >> > >> drivers/usb/host/xhci-tegra.c: In function ‘tegra_xusb_mbox_thread’: > >> drivers/usb/host/xhci-tegra.c:552:6: warning: ‘err’ may be used > >> uninitialized in this function [-Wuninitialized] > >> drivers/usb/host/xhci-tegra.c:482:6: note: ‘err’ was declared here > >> > >> Signed-off-by: Dongjiu Geng <gengdong...@huawei.com> > >> --- > > > > Any hint as to what commit caused this warning to show up? > > It seems below commit: > > commit e84fce0f8837496a48d11086829bdbe170358b7a > Author: Thierry Reding <tred...@nvidia.com> > Date: Thu Feb 11 18:10:48 2016 +0100 > > usb: xhci: Add NVIDIA Tegra XUSB controller driver > > Add support for the on-chip XUSB controller present on Tegra SoCs. This > controller, when loaded with external firmware, exposes an interface > compliant with xHCI. This driver loads the firmware, starts the > controller, and is able to service host-specific messages sent by the > controller's firmware. > > The controller also supports USB device mode as well as powergating > of the SuperSpeed and host-controller logic when not in use, but > support for these is not yet implemented. > > Based on work by: > Ajay Gupta <aj...@nvidia.com> > Bharath Yadav <bya...@nvidia.com> > Andrew Bresticker <abres...@chromium.org> > > Cc: Mathias Nyman <mathias.ny...@intel.com> > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > Acked-by: Mathias Nyman <mathias.ny...@linux.intel.com> > Signed-off-by: Thierry Reding <tred...@nvidia.com>
I've never seen this warning before. It's also a false positive in that technically the mailbox message will always have at least one bit set in "mask". However, I don't see how the compiler could know about it, given that the data comes from an external source, so I think this makes sense as a hint to the compiler. So: Acked-by: Thierry Reding <tred...@nvidia.com> Can you provide more detail on what exact version of which compiler you used that triggered this? I wonder why it's never presented itself with the compiler that I use. Thierry
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