59207e6380
Accessing the DDI_BUF_CTL register without the port's DDI clock being enabled (to set/clear the TypeC PHY ownership for the port) can lead to a corrupted value read during any i915 register access right after the DDI clock is enabled. The root cause is the way clock synchronization works for this register, controlled by the CHICKEN_DCPR_1 DDI_CLOCK_REG_ACCESS flag. Correctly this flag should be cleared on ADLP (see the Bspec link below), however after bootup the flag is set. One easily reproducible issue is an unclaimed register access of the PWR_WELL_CTL_DDI2 register, programmed right after DDI clock enabling to enable the port's DDI_IO power well (see the HSDES, VLK links below). With the correct setting above this problem can't be reproduced. Bspec: 49189 HSDES: 18019028154 VLK: 28328, 28655 Cc: Jouni Högander <jouni.hogander@intel.com> Cc: Arthur J Runyan <arthur.j.runyan@intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Acked-by: Arthur J Runyan <arthur.j.runyan@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220323201749.288566-1-imre.deak@intel.com
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.