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Filename Latest commit message Latest commit date
Jeffrey Hugo 1545befcf6 tty: serial: msm_serial: Fix flow control
commit b027ce258369cbfa88401a691c23dad01deb9f9b upstream.

hci_qca interfaces to the wcn3990 via a uart_dm on the msm8998 mtp and
Lenovo Miix 630 laptop.  As part of initializing the wcn3990, hci_qca
disables flow, configures the uart baudrate, and then reenables flow - at
which point an event is expected to be received over the uart from the
wcn3990.  It is observed that this event comes after the baudrate change
but before hci_qca re-enables flow. This is unexpected, and is a result of
msm_reset() being broken.

According to the uart_dm hardware documentation, it is recommended that
automatic hardware flow control be enabled by setting RX_RDY_CTL.  Auto
hw flow control will manage RFR based on the configured watermark.  When
there is space to receive data, the hw will assert RFR.  When the watermark
is hit, the hw will de-assert RFR.

The hardware documentation indicates that RFR can me manually managed via
CR when RX_RDY_CTL is not set.  SET_RFR asserts RFR, and RESET_RFR
de-asserts RFR.

msm_reset() is broken because after resetting the hardware, it
unconditionally asserts RFR via SET_RFR.  This enables flow regardless of
the current configuration, and would undo a previous flow disable
operation.  It should instead de-assert RFR via RESET_RFR to block flow
until the hardware is reconfigured.  msm_serial should rely on the client
to specify that flow should be enabled, either via mctrl() or the termios
structure, and only assert RFR in response to those triggers.

Fixes: 04896a77a9 ("msm_serial: serial driver for MSM7K onboard serial peripheral.")
Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Andy Gross <agross@kernel.org>
Link: https://lore.kernel.org/r/20191021154616.25457-1-jeffrey.l.hugo@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-13 08:42:22 +01:00
arch sparc64: implement ioremap_uc 2019-12-13 08:42:17 +01:00
block iocost: check active_list of all the ancestors in iocg_activate() 2019-11-14 13:56:54 -07:00
certs
crypto Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
Documentation x86/speculation: Fix incorrect MDS/TAA mitigation status 2019-11-29 10:09:46 +01:00
drivers tty: serial: msm_serial: Fix flow control 2019-12-13 08:42:22 +01:00
fs Revert "jffs2: Fix possible null-pointer dereferences in jffs2_add_frag_to_fragtree()" 2019-12-04 22:31:06 +01:00
include net/tls: use sg_next() to walk sg entries 2019-12-04 22:31:02 +01:00
init Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
ipc
kernel time: Zero the upper 32-bits in __kernel_timespec on 32-bit 2019-12-13 08:42:18 +01:00
lib lib/xz: fix XZ_DYNALLOC to avoid useless memory reallocations 2019-11-15 18:34:00 -08:00
LICENSES
mm mm/ksm.c: don't WARN if page is still mapped in remove_stable_node() 2019-11-22 09:11:18 -08:00
net tipc: fix link name length check 2019-12-04 22:31:03 +01:00
samples samples/bpf: fix build by setting HAVE_ATTR_TEST to zero 2019-10-31 21:39:15 +01:00
scripts arm64 fix for -rc8 / final 2019-11-15 09:14:23 -08:00
security efi/efi_test: Lock down /dev/efi_test and require CAP_SYS_ADMIN 2019-10-31 09:40:21 +01:00
sound ALSA: hda - Disable audio component for legacy Nvidia HDMI codecs 2019-11-29 10:10:19 +01:00
tools perf scripts python: exported-sql-viewer.py: Fix use of TRUE with SQLite 2019-12-13 08:42:16 +01:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM: Add a comment describing the /dev/kvm no_compat handling 2019-11-15 10:14:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-22 14:28:14 -08:00
Makefile Linux 5.4.2 2019-12-04 22:31:09 +01:00
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.