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Filename Latest commit message Latest commit date
Uwe Kleine-König 3296e566b0 gpio: pca953x: fix handling of automatic address incrementing
[ Upstream commit bcf41dc480b179bfb669a232080a2e26dc7294b4 ]

Some of the chips supported by the pca953x driver need the most
significant bit in the address word set to automatically increment the
address pointer on subsequent reads and writes (example: PCA9505). With
this bit unset the same register is read multiple times on a multi-byte
read sequence. Other chips must not have this bit set and autoincrement
always (example: PCA9555).

Up to now this AI bit was interpreted to be part of the address, which
resulted in inconsistent regmap caching when a register was written with
AI set and then read without it. This happened for the PCA9505 in
pca953x_gpio_set_multiple() where pca953x_read_regs() bulk read from the
cache for registers 0x8-0xc and then wrote to registers 0x88-0x8c. (Side
note: reading 5 values from offset 0x8 yiels OP0 5 times because AI must
be set to get OP0-OP4, which is another bug that is resolved here as a
by-product.) The same problem happens when calls to gpio_set_value() and
gpio_set_array_value() were mixed.

With this patch the AI bit is always set for chips that support it. This
works as there are no code locations that make use of the behaviour with
AI unset (for the chips that support it).

Note that the call to pca953x_setup_gpio() had to be done a bit earlier
to make the NBANK macro work.

The history of this bug is a bit complicated. Commit b32cecb46b
("gpio: pca953x: Extract the register address mangling to single
function") changed which chips and functions are affected. Commit
3b00691cc4 ("gpio: pca953x: hack to fix 24 bit gpio expanders") used
some duct tape to make the driver at least appear to work. Commit
4942723276 ("gpio: pca953x: Perform basic regmap conversion")
introduced the caching. Commit b4818afeac ("gpio: pca953x: Add
set_multiple to allow multiple bits to be set in one write.") introduced
the .set_multiple() callback which didn't work for chips that need the
AI bit which was fixed later for some chips in 8958262af3 ("gpio:
pca953x: Repair multi-byte IO address increment on PCA9575"). So I'm
sorry, I don't know which commit I should pick for a Fixes: line.

Tested-by: Marcel Gudert <m.gudert@eckelmann.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-24 17:50:22 +02:00
arch arm64: dts: qcom: fix pm8150 gpio interrupts 2020-06-24 17:50:21 +02:00
block iocost: don't let vrate run wild while there's no saturation signal 2020-06-22 09:31:06 +02:00
certs
crypto crypto: drbg - fix error return code in drbg_alloc_state() 2020-06-17 16:40:31 +02:00
Documentation dt-bindings: display: mediatek: control dpi pins mode to avoid leakage 2020-06-22 09:30:58 +02:00
drivers gpio: pca953x: fix handling of automatic address incrementing 2020-06-24 17:50:22 +02:00
fs virtiofs: schedule blocking async replies in separate worker 2020-06-24 17:50:21 +02:00
include usb: gadget: core: sync interrupt before unbind the udc 2020-06-24 17:50:16 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel kernel/cpu_pm: Fix uninitted local in cpu_pm 2020-06-22 09:31:22 +02:00
lib kasan: stop tests being eliminated as dead code with FORTIFY_SOURCE 2020-06-22 09:31:12 +02:00
LICENSES
mm mm: call cond_resched() from deferred_init_memmap() 2020-06-22 09:31:14 +02:00
net bpf, sockhash: Fix memory leak when unlinking sockets in sock_hash_free 2020-06-24 17:50:19 +02:00
samples samples: bpf: Fix build error 2020-06-03 08:21:15 +02:00
scripts mksysmap: Fix the mismatch of '.L' symbols in System.map 2020-06-24 17:50:19 +02:00
security apparmor: fix nnp subset test for unconfined 2020-06-24 17:50:20 +02:00
sound ALSA: usb-audio: Fix racy list management in output queue 2020-06-24 17:50:22 +02:00
tools perf symbols: Fix kernel maps for kcore and eBPF 2020-06-22 09:31:27 +02:00
usr
virt KVM: arm64: Save the host's PtrAuth keys in non-preemptible context 2020-06-17 16:40:38 +02:00
.clang-format
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.gitignore
.mailmap
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Kconfig
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Makefile Linux 5.4.48 2020-06-22 09:31:27 +02:00
README

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

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
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    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.