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84d49b3d08
Based on a sample of 7 DSDTs from Cherry Trail devices using an AXP288 PMIC depending on the design one of 2 possible LDOs on the PMIC is used for the MMC signalling voltage, either DLDO3 or GPIO1LDO (GPIO1 pin in low noise LDO mode). The Lenovo Miix 320-10ICR uses GPIO1LDO in the SHC1 ACPI device's DSM methods to set 3.3 or 1.8 signalling voltage and this appears to work as advertised, so presumably the device is actually using GPIO1LDO for the external microSD signalling voltage. But this device has a bug in the _PS0 method of the SHC1 ACPI device, the DSM remembers the last set signalling voltage and the _PS0 restores this after a (runtime) suspend-resume cycle, but it "restores" the voltage on DLDO3 instead of setting it on GPIO1LDO as the DSM method does. DLDO3 is used for the LCD and setting it to 1.8V causes the LCD to go black. This commit works around this issue by calling the Intel DSM to reset the signal voltage to 3.3V after the host has been runtime suspended. This will make the _PS0 method reprogram the DLDO3 voltage to 3.3V, which leaves it at its original setting fixing the LCD going black. This commit adds and uses a DMI quirk mechanism to only trigger this workaround on the Lenovo Miix 320 while leaving the behavior of the driver unchanged on other devices. BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=111294 BugLink: https://gitlab.freedesktop.org/drm/intel/issues/355 Reported-by: russianneuromancer <russianneuromancer@ya.ru> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Adrian Hunter <adrian.hunter@intel.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200316184753.393458-1-hdegoede@redhat.com Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> |
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| kernel | ||
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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.
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.