drm/amd/display: Fix flip-done timeouts on mode1 reset

The vblank on/off callbacks mixed use of amdgpu_irq_get/put() and
amdgpu_dm_crtc_set_vupdate_irq() to enable and disable IRQs.

With get/put, base driver will callback into DC to disable IRQs when
refcount == 0. With set_vupdate_irq(), DC is called directly to disable
IRQs, bypassing base driver's refcount tracking.

During gpu reset, base driver can restore IRQs via
amdgpu_irq_gpu_reset_resume_helper() > amdgpu_irq_update(). So if
get/put() is not used (i.e. refcount == 0), then vupdate_irq will be
disabled.

This is problematic if DRM requests vblank on before amdgpu_irq_update()
is called: drm_vblank_on() > set_vupdate_irq() enables vupdate_irq, but
the refcount is still 0. gpu_reset_resume_helper() > irq_update() then
immediately disables it, thus leading to flip done timeouts.

This is made worse on DCN since VUPDATE_NO_LOCK is the only IRQ enabled.
Prior to 8382cd234981, a combination of GRPH_FLIP and VSTARTUP IRQs were
used, and they used get/put(). This explains why 8382cd234981 exposed
this issue.

Fix by using get/put() instead of set_vupdate_irq(). DCE is unchanged,
since it relies on unbalanced enable/disable calls based on VRR status,
and hence requires direct set_vupdate_irq(). Plus, it also uses
GRPH_FLIP and VLINE IRQs, which are properly tracked by get/put().

Cc: stable@vger.kernel.org
Fixes: 8382cd234981 ("drm/amd/display: consolidate DCN vblank/flip handling onto vupdate_no_lock")
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Link: https://patch.msgid.link/20260723180159.52121-1-sunpeng.li@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

0 files changed, 0 insertions, 0 deletions