• Martin Wilck's avatar
    base/platform: Fix platform drivers with no probe callback · 25cad69f
    Martin Wilck authored
    Since b8b2c7d8, platform_drv_probe() is called for all platform
    devices. If drv->probe is NULL, and dev_pm_domain_attach() fails,
    platform_drv_probe() will return the error code from dev_pm_domain_attach().
    
    This causes real_probe() to enter the "probe_failed" path and set
    dev->driver to NULL. Before b8b2c7d8, real_probe() would assume
    success if both dev->bus->probe and drv->probe were missing. As a result,
    a device and driver could be "bound" together just by matching their names;
    this doesn't work any more after b8b2c7d8.
    
    This may cause problems later for certain usage of platform_driver_register()
    and platform_device_register_simple(). I observed a panic while loading
    the tpm_tis driver with parameter "force=1" (i.e. registering tpm_tis as
    a platform driver), because tpm_tis_init's assumption that the device
    returned by platform_device_register_simple() was bound didn't hold any more
    (tpmm_chip_alloc() dereferences chip->pdev->driver, causing panic).
    
    This patch restores the previous (4.3.0 and earlier) behavior of
    platform_drv_probe() in the case when the associated platform driver has
    no "probe" function.
    
    Fixes: b8b2c7d8 ("base/platform: assert that dev_pm_domain callbacks are called unconditionally")
    Signed-off-by: default avatarMartin Wilck <Martin.Wilck@ts.fujitsu.com>
    Cc: stable <stable@vger.kernel.org> # 4.4
    Cc: Martin Fuzzey <mfuzzey@parkeon.com>
    Acked-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    25cad69f
platform.c 36.1 KB