> From: Brian Norris [mailto:briannorris@xxxxxxxxxxxx] > Sent: Wednesday, November 23, 2016 8:10 AM > To: Amitkumar Karwar; Nishant Sarmukadam > Cc: linux-kernel@xxxxxxxxxxxxxxx; Kalle Valo; linux- > wireless@xxxxxxxxxxxxxxx; Cathy Luo; Dmitry Torokhov; Brian Norris > Subject: [PATCH] mwifiex: pcie: implement timeout loop for FW > programming doorbell > > Marvell Wifi PCIe modules don't always behave nicely for PCIe power > management when their firmware hasn't been loaded, particularly after > suspending the PCIe link one or more times. When this happens, we might > end up spinning forever in this status-polling tight loop. Let's make > this less tight by adding a timeout and by sleeping a bit in between > reads, as we do with the other similar loops. > > This prevents us from hogging a CPU even in such pathological cases, > and allows the FW initialization to just fail gracefully instead. > > I chose the same polling parameters as the earlier loop in this > function, and empirically, I found that this loop never makes it more > than about 12 cycles in a sane FW init sequence. I had no official > information on the actual intended latency for this portion of the > download. > > Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx> > --- > drivers/net/wireless/marvell/mwifiex/pcie.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c > b/drivers/net/wireless/marvell/mwifiex/pcie.c > index 4b89f557d0b6..9f9ea1350591 100644 > --- a/drivers/net/wireless/marvell/mwifiex/pcie.c > +++ b/drivers/net/wireless/marvell/mwifiex/pcie.c > @@ -2050,7 +2050,7 @@ static int mwifiex_prog_fw_w_helper(struct > mwifiex_adapter *adapter, > } > > /* Wait for the command done interrupt */ > - do { > + for (tries = 0; tries < MAX_POLL_TRIES; tries++) { > if (mwifiex_read_reg(adapter, PCIE_CPU_INT_STATUS, > &ireg_intr)) { > mwifiex_dbg(adapter, ERROR, > @@ -2062,8 +2062,18 @@ static int mwifiex_prog_fw_w_helper(struct > mwifiex_adapter *adapter, > ret = -1; > goto done; > } > - } while ((ireg_intr & CPU_INTR_DOOR_BELL) == > - CPU_INTR_DOOR_BELL); > + if (!(ireg_intr & CPU_INTR_DOOR_BELL)) > + break; > + usleep_range(10, 20); > + } > + if (ireg_intr & CPU_INTR_DOOR_BELL) { > + mwifiex_dbg(adapter, ERROR, "%s: Card failed to ACK > download\n", > + __func__); > + mwifiex_unmap_pci_memory(adapter, skb, > + PCI_DMA_TODEVICE); > + ret = -1; > + goto done; > + } > > mwifiex_unmap_pci_memory(adapter, skb, PCI_DMA_TODEVICE); > Patch looks fine to me. Acked-by: Amitkumar Karwar <akarwar@xxxxxxxxxxx> Regards, Amitkumar
