[v3,1/2] drm/i915: Prevent HW access during init from SDVO TV get_modes hook

Commit Message

Imre Deak Feb. 9, 2024, 4:03 p.m. UTC

Prevent accessing the HW from the SDVO/TV get_modes connector hook.
Returning 0 from the hook will make the caller -
drm_helper_probe_single_connector_modes() - return a default/EDID
override mode list to users. This matches the case where
intel_sdvo_get_tv_modes() fails to retrieve the current mode list due to
a HW access failure.

v2: Clarify the commit message wrt. which modes get_modes() returns. (Jouni)

Signed-off-by: Imre Deak <[e-mail]>
Reviewed-by: Jouni Högander <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
---
 drivers/gpu/drm/i915/display/intel_sdvo.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Imre Deak Feb. 9, 2024, 5:48 p.m. UTC | #1

On Fri, Feb 09, 2024 at 05:23:08PM +0000, Patchwork wrote:
> == Series Details ==
> 
> Series: series starting with [v3,1/2] drm/i915: Prevent HW access during init from SDVO TV get_modes hook
> URL   : https://patchwork.freedesktop.org/series/129727/
> State : failure
> 
> == Summary ==
> 
> Error: make failed
>   CALL    scripts/checksyscalls.sh
>   DESCEND objtool
>   INSTALL libsubcmd_headers
>   CC [M]  drivers/gpu/drm/i915/display/intel_sdvo.o
> drivers/gpu/drm/i915/display/intel_sdvo.c: In function ‘intel_sdvo_get_tv_modes’:
> drivers/gpu/drm/i915/display/intel_sdvo.c:2305:41: error: ‘i915’ undeclared (first use in this function); did you mean ‘I915’?
>  2305 |  if (!intel_display_driver_check_access(i915))
>       |                                         ^~~~
>       |                                         I915
> drivers/gpu/drm/i915/display/intel_sdvo.c:2305:41: note: each undeclared identifier is reported only once for each function it appears in
> make[6]: *** [scripts/Makefile.build:243: drivers/gpu/drm/i915/display/intel_sdvo.o] Error 1
> make[5]: *** [scripts/Makefile.build:481: drivers/gpu/drm/i915] Error 2
> make[4]: *** [scripts/Makefile.build:481: drivers/gpu/drm] Error 2
> make[3]: *** [scripts/Makefile.build:481: drivers/gpu] Error 2
> make[2]: *** [scripts/Makefile.build:481: drivers] Error 2
> make[1]: *** [/home/kbuild2/kernel/Makefile:1921: .] Error 2
> make: *** [Makefile:240: __sub-make] Error 2
> Build failed, no error log produced

Not sure why this fails, on latest drm-tip I get a different result, see
below.

Looks like an old tree is used as the base, could someone from the CI
team check this?

$ git fetch drm-tip
$ git reset --hard drm-tip/drm-tip
HEAD is now at 2aceb3c0b9c8c drm-tip: 2024y-02m-09d-12h-48m-25s UTC integration manifest
$ git am ~/imre.mbox
Applying: drm/i915: Prevent HW access during init from SDVO TV get_modes hook
Applying: drm/i915: Prevent HW access during init from connector get_modes hooks
$ make
  CALL    scripts/checksyscalls.sh
  DESCEND objtool
  INSTALL libsubcmd_headers
  CC [M]  drivers/gpu/drm/i915/display/intel_crt.o
  CC [M]  drivers/gpu/drm/i915/display/intel_dp_mst.o
  CC [M]  drivers/gpu/drm/i915/display/intel_dvo.o
  CC [M]  drivers/gpu/drm/i915/display/intel_sdvo.o
  LD [M]  drivers/gpu/drm/i915/i915.o
  CC [M]  drivers/gpu/drm/xe/i915-display/intel_dp_mst.o
  LD [M]  drivers/gpu/drm/xe/xe.o
  MODPOST Module.symvers
Kernel: arch/x86/boot/bzImage is ready  (#1476)
  LD [M]  drivers/gpu/drm/i915/i915.ko
  LD [M]  drivers/gpu/drm/xe/xe.ko

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_sdvo.c b/drivers/gpu/drm/i915/display/intel_sdvo.c
index 412c15d32f07e..c67605059aa3e 100644
--- a/drivers/gpu/drm/i915/display/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/display/intel_sdvo.c
@@ -2312,6 +2312,9 @@  static int intel_sdvo_get_tv_modes(struct drm_connector *connector)
 	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s]\n",
 		    connector->base.id, connector->name);
 
+	if (!intel_display_driver_check_access(i915))
+		return 0;
+
 	/*
 	 * Read the list of supported input resolutions for the selected TV
 	 * format.