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2d71ee0ce7
On some Bay Trail systems the GPU ACPI fwnode has power-resources which
point to the PMIC, which is connected over the LPSS I2C5 controller.
This one was quite nasty to debug, unlike on CHT where the same problem
leads to errors like these:
i2c_designware 808622C1:06: controller timed out
ACPI Error: AE_ERROR, Returned by Handler for [UserDefinedRegion]
ACPI Error: Method parse/execution failed \_SB.P18W._ON, AE_ERROR
video LNXVIDEO:00: Failed to change power state to D0
On BYT the read-modify-write done by drivers/acpi/pmic/intel_pmic_xpower.c
on the AXP288 PMIC register to change the power-resource state *seems* to
succeed.
But in reality, because the I2C controller has not been resumed yet, the
read silently fails and returns the wrong value, where as the write does
succeed, writing back the wrong value for all the other power-resources
in the same register, turning off a bunch of them. Which of course does
not end well.
This commit adds a RPM consumer link from the GPU (which has a LNXVIDEO
HID) to the BYT LPSS I2C5 controller, so that the I2C controller gets
resumed before the GPU is resumed and thus before we try to change the
power-resource.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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| .clang-format | ||
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| 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.
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.