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Fabio Estevam e8c220fac4 Revert "i2c: imx: improve the error handling in i2c_imx_dma_request()" Since commit `e1ab9a468e` ("i2c: imx: improve the error handling in i2c_imx_dma_request()") when booting with the DMA driver as module (such as CONFIG_FSL_EDMA=m) the following endless clk warnings are seen: [ 153.077831] ------------[ cut here ]------------ [ 153.082528] WARNING: CPU: 0 PID: 15 at drivers/clk/clk.c:924 clk_core_disable_lock+0x18/0x24 [ 153.093077] i2c0 already disabled [ 153.096416] Modules linked in: [ 153.099521] CPU: 0 PID: 15 Comm: kworker/0:1 Tainted: G W 5.2.0+ #321 [ 153.107290] Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree) [ 153.113772] Workqueue: events deferred_probe_work_func [ 153.118979] [<c0019560>] (unwind_backtrace) from [<c0014734>] (show_stack+0x10/0x14) [ 153.126778] [<c0014734>] (show_stack) from [<c083f8dc>] (dump_stack+0x9c/0xd4) [ 153.134051] [<c083f8dc>] (dump_stack) from [<c0031154>] (__warn+0xf8/0x124) [ 153.141056] [<c0031154>] (__warn) from [<c0031248>] (warn_slowpath_fmt+0x38/0x48) [ 153.148580] [<c0031248>] (warn_slowpath_fmt) from [<c040fde0>] (clk_core_disable_lock+0x18/0x24) [ 153.157413] [<c040fde0>] (clk_core_disable_lock) from [<c058f520>] (i2c_imx_probe+0x554/0x6ec) [ 153.166076] [<c058f520>] (i2c_imx_probe) from [<c04b9178>] (platform_drv_probe+0x48/0x98) [ 153.174297] [<c04b9178>] (platform_drv_probe) from [<c04b7298>] (really_probe+0x1d8/0x2c0) [ 153.182605] [<c04b7298>] (really_probe) from [<c04b7554>] (driver_probe_device+0x5c/0x174) [ 153.190909] [<c04b7554>] (driver_probe_device) from [<c04b58c8>] (bus_for_each_drv+0x44/0x8c) [ 153.199480] [<c04b58c8>] (bus_for_each_drv) from [<c04b746c>] (__device_attach+0xa0/0x108) [ 153.207782] [<c04b746c>] (__device_attach) from [<c04b65a4>] (bus_probe_device+0x88/0x90) [ 153.215999] [<c04b65a4>] (bus_probe_device) from [<c04b6a04>] (deferred_probe_work_func+0x60/0x90) [ 153.225003] [<c04b6a04>] (deferred_probe_work_func) from [<c004f190>] (process_one_work+0x204/0x634) [ 153.234178] [<c004f190>] (process_one_work) from [<c004f618>] (worker_thread+0x20/0x484) [ 153.242315] [<c004f618>] (worker_thread) from [<c0055c2c>] (kthread+0x118/0x150) [ 153.249758] [<c0055c2c>] (kthread) from [<c00090b4>] (ret_from_fork+0x14/0x20) [ 153.257006] Exception stack(0xdde43fb0 to 0xdde43ff8) [ 153.262095] 3fa0: 00000000 00000000 00000000 00000000 [ 153.270306] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 153.278520] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 [ 153.285159] irq event stamp: 3323022 [ 153.288787] hardirqs last enabled at (3323021): [<c0861c4c>] _raw_spin_unlock_irq+0x24/0x2c [ 153.297261] hardirqs last disabled at (3323022): [<c040d7a0>] clk_enable_lock+0x10/0x124 [ 153.305392] softirqs last enabled at (3322092): [<c000a504>] __do_softirq+0x344/0x540 [ 153.313352] softirqs last disabled at (3322081): [<c00385c0>] irq_exit+0x10c/0x128 [ 153.320946] ---[ end trace a506731ccd9bd703 ]--- This endless clk warnings behaviour is well explained by Andrey Smirnov: "Allocating DMA after registering I2C adapter can lead to infinite probing loop, for example, consider the following scenario: 1. i2c_imx_probe() is called and successfully registers an I2C adapter via i2c_add_numbered_adapter() 2. As a part of i2c_add_numbered_adapter() new I2C slave devices are added from DT which results in a call to driver_deferred_probe_trigger() 3. i2c_imx_probe() continues and calls i2c_imx_dma_request() which due to lack of proper DMA driver returns -EPROBE_DEFER 4. i2c_imx_probe() fails, removes I2C adapter and returns -EPROBE_DEFER, which places it into deferred probe list 5. Deferred probe work triggered in #2 above kicks in and calls i2c_imx_probe() again thus bringing us to step #1" So revert commit `e1ab9a468e` ("i2c: imx: improve the error handling in i2c_imx_dma_request()") and restore the old behaviour, in order to avoid regressions on existing setups. Cc: <stable@vger.kernel.org> Reported-by: Andrey Smirnov <andrew.smirnov@gmail.com> Reported-by: Russell King <linux@armlinux.org.uk> Fixes: `e1ab9a468e` ("i2c: imx: improve the error handling in i2c_imx_dma_request()") Signed-off-by: Fabio Estevam <festevam@gmail.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>		2019-08-14 11:53:00 +02:00
arch	RISC-V updates for v5.3-rc4	2019-08-10 16:31:47 -07:00
block	block, bfq: handle NULL return value by bfq_init_rq()	2019-08-08 07:31:50 -06:00
certs	Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs"	2019-07-10 18:43:43 -07:00
crypto	USB / PHY patches for 5.3-rc1	2019-07-11 15:40:06 -07:00
Documentation	RISC-V updates for v5.3-rc4	2019-08-10 16:31:47 -07:00
drivers	Revert "i2c: imx: improve the error handling in i2c_imx_dma_request()"	2019-08-14 11:53:00 +02:00
fs	dax fixes v5.3-rc4	2019-08-11 13:15:10 -07:00
include	Bugfixes (arm and x86) and cleanups.	2019-08-09 15:46:29 -07:00
init	Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-07-19 10:42:02 -07:00
ipc	Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-07-19 10:42:02 -07:00
kernel	Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-08-10 15:48:02 -07:00
lib	Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net	2019-08-06 17:11:59 -07:00
LICENSES	LICENSES: Rename other to deprecated	2019-05-03 06:34:32 -06:00
mm	mm/memremap: Fix reuse of pgmap instances with internal references	2019-08-09 14:16:15 -07:00
net	net: dsa: sja1105: Fix memory leak on meta state machine error path	2019-08-06 14:37:02 -07:00
samples	treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again	2019-07-25 11:05:10 +02:00
scripts	kbuild: show hint if subdir-y/m is used to visit module Makefile	2019-08-10 01:45:31 +09:00
security	selinux/stable-5.3 PR 20190801	2019-08-02 18:40:49 -07:00
sound	sound fixes for 5.3-rc4	2019-08-09 09:21:27 -07:00
tools	Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-08-10 16:19:02 -07:00
usr	kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test	2019-07-23 10:45:46 +02:00
virt	KVM/arm fixes for 5.3, take #2	2019-08-09 16:53:50 +02:00
.clang-format	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2019-04-17 11:26:25 -07:00
.cocciconfig
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore	.gitignore: Add compilation database file	2019-07-27 12:18:19 +09:00
.mailmap	MAINTAINERS: Update my email address	2019-07-22 14:57:50 +01:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	Remove references to dead website.	2019-07-19 12:22:04 -07:00
Kbuild	Kbuild updates for v5.1	2019-03-10 17:48:21 -07:00
Kconfig	docs: kbuild: convert docs to ReST and rename to *.rst	2019-06-14 14:21:21 -06:00
MAINTAINERS	Char/misc fixes for 5.3-rc4	2019-08-10 12:24:20 -07:00
Makefile	Linux 5.3-rc4	2019-08-11 13:26:41 -07:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.