drm/radeon: adjust pll when audio is not enabled

commit 7fe04d6f upstream.

Fixes display problems with some monitors when audio
is not enabled.

Bugs:
https://bugs.freedesktop.org/show_bug.cgi?id=89505
https://bugzilla.kernel.org/show_bug.cgi?id=94171
Plus several reports on IRC.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -580,6 +580,9 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
 		else
 			radeon_crtc->pll_flags |= RADEON_PLL_PREFER_LOW_REF_DIV;
 
+		/* if there is no audio, set MINM_OVER_MAXP  */
+		if (!drm_detect_monitor_audio(radeon_connector_edid(connector)))
+			radeon_crtc->pll_flags |= RADEON_PLL_PREFER_MINM_OVER_MAXP;
 		if (rdev->family < CHIP_RV770)
 			radeon_crtc->pll_flags |= RADEON_PLL_PREFER_MINM_OVER_MAXP;
 		/* use frac fb div on APUs */