On Thu, Mar 16, 2023 at 04:25:58PM +0100, Arnd Bergmann wrote: > On Wed, Mar 15, 2023, at 16:51, Manivannan Sadhasivam wrote: > > On Wed, Mar 08, 2023 at 06:03:06PM +0900, Damien Le Moal wrote: > >> + /* > >> + * Set the status before raising the IRQ to ensure that the host sees > >> + * the updated value when it gets the IRQ. > >> + */ > >> + WRITE_ONCE(reg->status, status); > > > > For MMIO, it is not sufficient to use WRITE_ONCE() and expect that the write > > has reached the memory (it could be stored in a write buffer). If you really > > care about synchronization, then you should do a read back of the variable. > > This is not MMIO, this is the local access to a variable that is accessed > through MMIO from the remote host. Reading it back would not change anything > here as far as I can tell, > Ah, sorry I got confused this with my EPF driver... Yeah for a variable WRITE_ONCE is sufficient. Thanks, Mani > Arnd -- மணிவண்ணன் சதாசிவம்
