On Mon, Jun 15, 2020 at 05:20:14PM +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ca8b19d61e3fce5d2d7790cde27a0b57bcb3f341 Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@xxxxxxxxx>
Date: Mon, 25 May 2020 14:25:01 +0200
Subject: [PATCH] spi: dw: Fix controller unregister order
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: 04f421e7b0b1 ("spi: dw: use managed resources")
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v3.14+
Cc: Baruch Siach <baruch@xxxxxxxxxx>
Link: https://lore.kernel.org/r/3fff8cb8ae44a9893840d0688be15bb88c090a14.1590408496.git.lukas@xxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
I took this additional patch:
66b19d762378 ("spi: dw: fix possible race condition")
And worked around the renames in :
721483e28889 ("spi: dw: Convert to generalized SPI controller API")
And queued these two patches for 4.14, 4.9, and 4.4.
--
Thanks,
Sasha
