forked from luck/tmp_suning_uos_patched
002ee28e8b
pwrseq_emmc.c implements a HW reset procedure for eMMC chip by driving a
GPIO line.
It registers the .reset() cb on mmc_pwrseq_ops and it registers a system
restart notification handler; both of them perform reset by unconditionally
calling gpiod_set_value().
If the eMMC reset line is tied to a GPIO controller whose driver can sleep
(i.e. I2C GPIO controller), then the kernel would spit warnings when trying
to reset the eMMC chip by means of .reset() mmc_pwrseq_ops cb (that is
exactly what I'm seeing during boot).
Furthermore, on system reset we would gets to the system restart
notification handler with disabled interrupts - local_irq_disable() is
called in machine_restart() at least on ARM/ARM64 - and we would be in
trouble when the GPIO driver tries to sleep (which indeed doesn't happen
here, likely because in my case the machine specific code doesn't call
do_kernel_restart(), I guess..).
This patch fixes the .reset() cb to make use of gpiod_set_value_cansleep(),
so that the eMMC gets reset on boot without complaints, while, since there
isn't that much we can do, we avoid register the restart handler if the
GPIO controller has a sleepy driver (and we spit a dev_notice() message to
let people know)..
This had been tested on a downstream 4.9 kernel with backported
commit 83f37ee7ba33 ("mmc: pwrseq: Add reset callback to the struct
mmc_pwrseq_ops") and commit ae60fb031cf2 ("mmc: core: Don't do eMMC HW
reset when resuming the eMMC card"), because I couldn't boot my board
otherwise. Maybe worth to RFT.
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
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| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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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.