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SubjectRE: [PATCH] mwifiex: pcie: implement timeout loop for FW programming doorbell
Date
> From: Brian Norris [mailto:briannorris@chromium.org]
> Sent: Wednesday, November 23, 2016 8:10 AM
> To: Amitkumar Karwar; Nishant Sarmukadam
> Cc: linux-kernel@vger.kernel.org; Kalle Valo; linux-
> wireless@vger.kernel.org; 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@chromium.org>
> ---
> 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@marvell.com>

Regards,
Amitkumar

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