| Message ID | 20171206105724.5603-1-drake@endlessm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 6 December 2017 at 11:57, Daniel Drake <drake@endlessm.com> wrote: > The Weibu F3C MiniPC has an onboard AP6255 module, presenting > two SDIO functions on a single MMC host (Bluetooth/btsdio and > WiFi/brcmfmac), and the mmc layer correctly detects this as > non-removable. > > After suspend/resume, the wifi and bluetooth interfaces disappear > and do not get probed again. > > The conditions here are: > > 1. During suspend, we reach mmc_pm_notify() > > 2. mmc_pm_notify() calls mmc_sdio_pre_suspend() to see if we can > suspend the SDIO host. However, mmc_sdio_pre_suspend() returns > -ENOSYS because btsdio_driver does not have a suspend method. > > 3. mmc_pm_notify() proceeds to remove the card > > 4. Upon resume, mmc_rescan() does nothing with this host, because of > the rescan_entered check which aims to only scan a non-removable > device a single time (i.e. during boot). Thanks for detailed description of the problem, it really helps! > > Fix the loss of functionality by permitting another rescan of > non-removable devices when we forcefully remove a card under these > conditions. No, I don't like this solution, simply because I think it's a workaround rather than a proper fix. I think the SDIO func drivers should implement the suspend/resume callbacks instead. One may argue that the mmc_pm_notify() then shouldn't have removed the card in first place if the cards are non-removable. Maybe we should just print a warning in that case instead. > > Signed-off-by: Daniel Drake <drake@endlessm.com> > --- > drivers/mmc/core/core.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 1f0f44f4dd5f..e436cde50bc4 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -2966,6 +2966,10 @@ static int mmc_pm_notify(struct notifier_block *notify_block, > mmc_power_off(host); > mmc_release_host(host); > host->pm_flags = 0; > + > + /* Force a rescan on resume, even for non-removable cards */ > + host->rescan_entered = 0; > + > break; > > case PM_POST_SUSPEND: > -- > 2.14.1 > Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 1f0f44f4dd5f..e436cde50bc4 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -2966,6 +2966,10 @@ static int mmc_pm_notify(struct notifier_block *notify_block, mmc_power_off(host); mmc_release_host(host); host->pm_flags = 0; + + /* Force a rescan on resume, even for non-removable cards */ + host->rescan_entered = 0; + break; case PM_POST_SUSPEND:
The Weibu F3C MiniPC has an onboard AP6255 module, presenting two SDIO functions on a single MMC host (Bluetooth/btsdio and WiFi/brcmfmac), and the mmc layer correctly detects this as non-removable. After suspend/resume, the wifi and bluetooth interfaces disappear and do not get probed again. The conditions here are: 1. During suspend, we reach mmc_pm_notify() 2. mmc_pm_notify() calls mmc_sdio_pre_suspend() to see if we can suspend the SDIO host. However, mmc_sdio_pre_suspend() returns -ENOSYS because btsdio_driver does not have a suspend method. 3. mmc_pm_notify() proceeds to remove the card 4. Upon resume, mmc_rescan() does nothing with this host, because of the rescan_entered check which aims to only scan a non-removable device a single time (i.e. during boot). Fix the loss of functionality by permitting another rescan of non-removable devices when we forcefully remove a card under these conditions. Signed-off-by: Daniel Drake <drake@endlessm.com> --- drivers/mmc/core/core.c | 4 ++++ 1 file changed, 4 insertions(+)