On Tue, Apr 30, 2019 at 04:27:41PM +0800, Liuyixian (Eason) wrote: > > > On 2019/4/27 5:05, Leon Romanovsky wrote: > > On Fri, Apr 26, 2019 at 11:36:56AM -0300, Jason Gunthorpe wrote: > >> On Fri, Apr 26, 2019 at 06:12:11PM +0800, Liuyixian (Eason) wrote: > >> > >>> However, I have talked with our chip team about function clear > >>> functionality. We think it is necessary to inform the chip to > >>> perform the outstanding task and some cleanup work and restore > >>> hardware resources in time when rmmod ko. Otherwise, it is > >>> dangerous to reuse the hardware as it can not guarantee those > >>> work can be done well without the notification from our driver. > >> > >> If it is dangerous to reuse the hardware then you have to do this > >> cleanup on device startup, not on device removal. > > > > Right, I can think about gazillion ways to brick such HW. > > The simplest way will be to call SysRq during RDMA traffic > > and no cleanup function will be called in such case. > > > > Thanks > > Hi Jason and Leon, > > As hip08 is a fake pcie device, we could not disassociate and stop the hardware access > through the chain break mechanism as a real pcie device. Alternatively, function clear > is used as a notification to the hardware to stop accessing and ensure to not read or > write DDR later. That is, the role of function clear to hip08 is similar as the chain > break to pcie device. What? This hardware is broken and doesn't respond to the bus master enable bit in the PCI config space?? Jason
