• Daniel Drake's avatar
    mmc: avoid removing non-removable hosts during suspend · 3ed000cd
    Daniel Drake authored
    
    [ Upstream commit de8dcc3d ]
    
    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 detecting that we are unable to
    suspend a non-removable host, so avoid the forced removal in that
    case. The comment above this function already indicates that this
    code was only intended for removable devices.
    Signed-off-by: default avatarDaniel Drake <drake@endlessm.com>
    Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
    Signed-off-by: default avatarSasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    3ed000cd
core.c 70.6 KB