Linus Walleij 3760557c3a mmc: spi: Toggle SPI polarity, do not hardcode it
commit af3ed119329cf9690598c5a562d95dfd128e91d6 upstream.

The code in mmc_spi_initsequence() tries to send a burst with
high chipselect and for this reason hardcodes the device into
SPI_CS_HIGH.

This is not good because the SPI_CS_HIGH flag indicates
logical "asserted" CS not always the physical level. In
some cases the signal is inverted in the GPIO library and
in that case SPI_CS_HIGH is already set, and enforcing
SPI_CS_HIGH again will actually drive it low.

Instead of hard-coding this, toggle the polarity so if the
default is LOW it goes high to assert chipselect but if it
is already high then toggle it low instead.

Cc: Phil Elwell <phil@raspberrypi.org>
Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20191204152749.12652-1-linus.walleij@linaro.org
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-14 16:32:09 -05:00
2020-01-27 14:46:19 +01:00
2020-02-05 14:18:29 +00:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

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

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.
Description
No description provided
Readme 1.4 GiB
Languages
C 98.1%
Assembly 1.2%
Makefile 0.3%