Re: omap_hsmmc: sdio: issue with generic wakeup IRQ handling

[Vishal Thanki <vishalthanki@gmail.com>]

Hi Andreas,

On Thu, Feb 18, 2016 at 10:31:04PM +0100, Andreas Fenkart wrote:
> Hi Vishal,
> 
> I remember there was a problem with IRQ, but can't remember on top of
> my head. Meanwhile this might be some pointer:
> 
> diff --git a/drivers/net/wireless/mwifiex/sta_ioctl.c
> b/drivers/net/wireless/mwifiex/sta_ioctl.c
> index a6c8a4f..67587c2 100644
> --- a/drivers/net/wireless/mwifiex/sta_ioctl.c
> +++ b/drivers/net/wireless/mwifiex/sta_ioctl.c
> @@ -517,6 +517,17 @@ int mwifiex_enable_hs(struct mwifiex_adapter *adapter)
>         adapter->hs_enabling = true;
>         mwifiex_cancel_all_pending_cmd(adapter);
> 
> +       /* if the MMC host is already in suspend it will not detect SDIO irq
> +        * and we might run into response timeout. By claiming the MMC host we
> +        * wake it up, which is sufficient to detect a pending IRQ
> +        */
> +       {
> +               struct sdio_mmc_card *card = adapter->card;
> +               sdio_claim_host(card->func);
> +               printk("+++ poll mmc host for IRQ +++\n");
> +               sdio_release_host(card->func);
> +       }
> +
>         if (mwifiex_set_hs_params(mwifiex_get_priv(adapter,
>                                                    MWIFIEX_BSS_ROLE_STA),
>                                   HostCmd_ACT_GEN_SET, MWIFIEX_SYNC_CMD,

I tried this code change but that did not help. I saw that the code
change is in a function called mwifiex_enable_hs(), which only gets
invoked by mwifiex_sdio_suspend(); which is why I think it is not having
any effect. Because when I run the command to scan the channel list
(i.e. iw dev wlan0 scan), the system is not in suspend state. And I
noticed (by adding prints in omap_hsmmc.c for suspend and resume
callbacks) that during the "scan" command, the suspend routine gets invoked
for HSMMC but it never gets resumed (may be due to the missed wakeup
IRQ) from mwifiex and the command times out.

Thanks for your help.

Vishal


> 
> 2016-02-18 19:27 GMT+01:00 Vishal Thanki <vishalthanki@gmail.com>:
> > Hi,
> >
> > On a custom built am335x based board, I am facing an issue mwifiex wifi
> > module which is connected to host via SDIO interface. I am using kernel
> > version 4.4.
> >
> > The problem is related to the wifi "ext_scan" command getting timed out
> > over SDIO. This was working with old kernel (v4.0), but does not work on
> > kernel v4.4. I found the following commit is responsible for this
> > behavior.
> >
> > =================================
> > 5b83b2234be6733cfe22036c38031b2c890b3db8
> >
> > mmc: omap_hsmmc: Change wake-up interrupt to use generic wakeirq
> >
> > We can now use generic wakeirq handling and remove the custom handling
> > for the wake-up interrupts.
> > =================================
> >
> > There is no wifi issue if I revert the above mentioned commit on kernel
> > v4.4.
> >
> > I see that before this commit, the wakeup IRQ handler was registered
> > within the omap_hsmmc.c itself with additional IRQF_TRIGGER_LOW flag.
> > But with the introduction to dev_pm_set_dedicated_wake_irq(), the
> > generic wakeup IRQ handler is registered which does not take the
> > IRQF_TRIGGER flag. I am not sure if that is the issue, but I added that
> > IRQF_TRIGGER_LOW flag in dev_pm_set_dedicated_wake_irq() while
> > registering a threaded IRQ handler, I could see the problem disappears.
> > However, this change is causing the infinite interrupts because the of
> > level triggered interrupt is not handled in generic wakeup IRQ handling
> > code (as it was done specially in omap_hsmmc.c code earlier).
> >
> > I am not much familiar with MMC/SDIO driver and I am not sure how to fix
> > this behavior. So any guidance would be really helpful.
> >
> > Thanks,
> > Vishal