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This patch was triggered by a remark from Russell that
introducing a call to the waituart (needed to fix debug prints
on the Qualcomm platforms) was dangerous because in some cases
this will involve waiting for a modem CTS (clear to send)
signal, and debug messages would maybe not work on platforms
with no modem connected to the UART port: they will just
hang waiting for the modem to assert CTS and this might never
happen.
Looking through all UART debug drivers implementing the waituart
macro I discovered that all users except two actually use this
macro to check if the UART is ready for TX, let's call this
TXRDY.
Only two debug UART drivers actually check for CTS:
- arch/arm/include/debug/8250.S
- arch/arm/include/debug/tegra.S
The former is very significant since the 8250 is possibly
the most common UART on the planet.
We have the following problem: the semantics of waituart are
ambiguous making it dangerous to introduce the macro to debug
code fixing debug prints for Qualcomm. To start to pry this
problem apart, this patch does the following:
- Convert all debug UART drivers to define two macros:
- waituartcts with the clear semantic to wait for CTS
to be asserted
- waituarttxrdy with the clear semantic to wait for the TX
capability of the UART to be ready
- When doing this take care to assign the right function to
each drivers macro, so they now do exactly the above.
- Update the three sites in the kernel invoking the waituart
macro to call waituartcts/waituarttxrdy in sequence, so that
the functional impact on the kernel should be zero.
After this we can start to change the code sites using this
code to do the right thing.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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Based on 1 normalized pattern(s):
this software is licensed under the terms of the gnu general public
license version 2 as published by the free software foundation and
may be copied distributed and modified under those terms this
program is distributed in the hope that it will be useful but
without any warranty without even the implied warranty of
merchantability or fitness for a particular purpose see the gnu
general public license for more details
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 285 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141900.642774971@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The maintainers for mach-msm no longer have any plans to support
or test the platforms supported by this architecture[1]. Most likely
there aren't any active users of this code anyway, so let's
delete it.
[1] http://lkml.kernel.org/r/20150307031212.GA8434@fifo99.com
Cc: David Brown <davidb@codeaurora.org>
Cc: Bryan Huntsman <bryanh@codeaurora.org>
Cc: Daniel Walker <dwalker@fifo99.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>
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If the CPU is in big-endian mode these macros will access the
hardware incorrectly. Reverse thins as necessary to fix this.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>
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Separate Qualcomm low-level debugging UART to two options.
DEBUG_MSM_UART is used in earlier non-multi platform arches,
like MSM7X00A, QSD8X50 and MSM7X30.
DEBUG_QCOM_UARTDM is used in multi-plafrom arches and have
embedded data mover.
Make DEBUG_UART_PHYS and DEBUG_UART_BASE user adjustable by
Kconfig menu.
Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>
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Add debug uart support for MSM8974. This patch adds a Kconfig
entry and the base address for the debug uart.
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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One more step to allowing MSM to participate in the
multi-platform defconfig.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
[davidb: Comment cleanup requested by sboyd]
Signed-off-by: David Brown <davidb@codeaurora.org>
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