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5ad773f9a9
If the VGA connector has no DDC channel, an error pointer will be
dereferenced, e.g. on Salvator-XS:
Unable to handle kernel NULL pointer dereference at virtual address 000000000000017d
...
Call trace:
sysfs_do_create_link_sd.isra.0+0x40/0x108
sysfs_create_link+0x20/0x40
drm_sysfs_connector_add+0xa8/0xc8
drm_connector_register.part.3+0x54/0xb0
drm_connector_register_all+0xb0/0xd0
drm_modeset_register_all+0x54/0x88
drm_dev_register+0x18c/0x1d8
rcar_du_probe+0xe4/0x150
...
This happens because vga->ddc either contains a valid DDC channel
pointer, or -ENODEV, and drm_connector_init_with_ddc() expects a valid
DDC channel pointer, or NULL.
Fix this by resetting vga->ddc to NULL in case of -ENODEV, and replacing
the existing error checks by non-NULL checks.
This is similar to what the HDMI connector driver does.
Fixes: a4f9087e85 ("drm/bridge: dumb-vga-dac: Provide ddc symlink in connector sysfs directory")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813093046.4976-1-geert+renesas@glider.be
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.