Daniel Mack <daniel@xxxxxxxxxx> wrote: > When wcn36xx_dxe_tx_frame() is entered while the device is still processing > the queue asyncronously, we are racing against the firmware code with > updates to the buffer descriptors. Presumably, the firmware scans the ring > buffer that holds the descriptors and scans for a valid control descriptor, > and then assumes that the next descriptor contains the payload. If, however, > the control descriptor is marked valid, but the payload descriptor isn't, > the packet is not sent out. > > Another issue with the current code is that is lacks memory barriers before > descriptors are marked valid. This is important because the CPU may reorder > writes to memory, even if it is allocated as coherent DMA area, and hence > the device may see incompletely written data. > > To fix this, the code in wcn36xx_dxe_tx_frame() was restructured a bit so > that the payload descriptor is made valid before the control descriptor. > Memory barriers are added to ensure coherency of shared memory areas. > > Signed-off-by: Daniel Mack <daniel@xxxxxxxxxx> > Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx> 10 patches applied to ath-next branch of ath.git, thanks. 9a81cc23dfef wcn36xx: fix buffer commit logic on TX path 57e06e0e2a86 wcn36xx: set DMA mask explicitly ba437e72378c wcn36xx: don't disable RX IRQ from handler edd23ab403cf wcn36xx: clear all masks in RX interrupt ce1d4be82b10 wcn36xx: only handle packets when ED or DONE bit is set 18c7ed138824 wcn36xx: consider CTRL_EOP bit when looking for valid descriptors 2a46c829a926 wcn36xx: set PREASSOC and IDLE stated when BSS info changes 773f9a28bcda wcn36xx: drain pending indicator messages on shutdown a50c6c8412f7 wcn36xx: simplify wcn36xx_smd_open() ffbc9197b472 wcn36xx: improve debug and error messages for SMD -- https://patchwork.kernel.org/patch/10404031/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
