• Lukas Wunner's avatar
    spi: dw: Fix controller unregister order · ca8b19d6
    Lukas Wunner authored
    The Designware SPI driver uses devm_spi_register_controller() on bind.
    As a consequence, on unbind, __device_release_driver() first invokes
    dw_spi_remove_host() before unregistering the SPI controller via
    devres_release_all().
    
    This order is incorrect:  dw_spi_remove_host() shuts down the chip,
    rendering the SPI bus inaccessible even though the SPI controller is
    still registered.  When the SPI controller is subsequently unregistered,
    it unbinds all its slave devices.  Because their drivers cannot access
    the SPI bus, e.g. to quiesce interrupts, the slave devices may be left
    in an improper state.
    
    As a rule, devm_spi_register_controller() must not be used if the
    ->remove() hook performs teardown steps which shall be performed after
    unregistering the controller and specifically after unbinding of slaves.
    
    Fix by reverting to the non-devm variant of spi_register_controller().
    
    An alternative approach would be to use device-managed functions for all
    steps in dw_spi_remove_host(), e.g. by calling devm_add_action_or_reset()
    on probe.  However that approach would add more LoC to the driver and
    it wouldn't lend itself as well to backporting to stable.
    
    Fixes: 04f421e7 ("spi: dw: use managed resources")
    Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
    Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
    Cc: stable@vger.kernel.org # v3.14+
    Cc: Baruch Siach <baruch@tkos.co.il>
    Link: https://lore.kernel.org/r/3fff8cb8ae44a9893840d0688be15bb88c090a14.1590408496.git.lukas@wunner.deSigned-off-by: default avatarMark Brown <broonie@kernel.org>
    ca8b19d6
spi-dw.c 14.7 KB