On Tuesday, April 10, 2018 08:17 PM, Ramon Fried wrote: > On 10 April 2018 at 20:35, Daniel Mack <daniel@xxxxxxxxxx> wrote: >> When accessing shared memory to check for the stat of submitted >> descriptors, make sure to use READ_ONCE(). This will guarantee the >> compiler treats these memory locations as volatile and doesn't apply >> any caching. > > The structure that is tested is not shared memory. It's accessed only > by the apps processor. Hmm? ctl->desc is of type struct wcn36xx_dxe_desc, which is packed and shared with the firmware. The WCN36xx_DXE_CTRL_VLD bit in ctrl bitfield is set by the firmware when a frame is valid, and before asserting the RX interrupt. So the host CPU must treat it as volatile and expect it to change. Am I reading this wrong? Thanks, Daniel
