mirror of https://gitee.com/openkylin/linux.git
674fa8daa8
While sorting out some devicetree issues I found that the pinctrl driver
was failing to acquire its GFX regmap even though the phandle was
present in the devicetree:
[ 0.124190] aspeed-g5-pinctrl 1e6e2000.syscon:pinctrl: No GFX phandle found, some mux configurations may fail
Without access to the GFX regmap we fail to configure the mux for the
VPO function:
[ 1.548866] pinctrl core: add 1 pinctrl maps
[ 1.549826] aspeed-g5-pinctrl 1e6e2000.syscon:pinctrl: found group selector 164 for VPO
[ 1.550638] aspeed-g5-pinctrl 1e6e2000.syscon:pinctrl: request pin 144 (V20) for 1e6e6000.display
[ 1.551346] aspeed-g5-pinctrl 1e6e2000.syscon:pinctrl: request pin 145 (U19) for 1e6e6000.display
...
[ 1.562057] aspeed-g5-pinctrl 1e6e2000.syscon:pinctrl: request pin 218 (T22) for 1e6e6000.display
[ 1.562541] aspeed-g5-pinctrl 1e6e2000.syscon:pinctrl: request pin 219 (R20) for 1e6e6000.display
[ 1.563113] Muxing pin 144 for VPO
[ 1.563456] Want SCU8C[0x00000001]=0x1, got 0x0 from 0x00000000
[ 1.564624] aspeed_gfx 1e6e6000.display: Error applying setting, reverse things back
This turned out to be a simple problem of timing: The ASPEED pinctrl
driver is probed during arch_initcall(), while GFX is processed much
later. As such the GFX syscon is not yet registered during the pinctrl
probe() and we get an -EPROBE_DEFER when we try to look it up, however
we must not defer probing the pinctrl driver for the inability to mux
some GFX-related functions.
Switch to lazily grabbing the regmaps when they're first required by the
mux configuration. This generates a bit of noise in the patch as we have
to drop the `const` qualifier on arguments for several function
prototypes, but has the benefit of working.
I've smoke tested this for the ast2500-evb under qemu with a dummy
graphics device. We now succeed in our attempts to configure the SoC's
VPO pinmux function.
Fixes:
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|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.