drm/i915/vga: Consolidate intel_vga_disable() calls

Currently we disable the VGA plane from various places, sometimes
multiple times in the same init/resume sequence. Get rid of all this
mess and do it just once. The most correct place seems to be just
after intel_early_display_was() as that one applies various workarounds
that need to be in place before we touch any planes (including the
VGA plane).

Actually, we do still have a second caller in
vlv_display_power_well_init(). I think we still need that as the reset
value of VGACNTR is 0x0 and thus technically the VGA plane will be
(at least partially) enabled after the power well has been toggled.

In both cases we have the necessary power reference already held
(INIT power domain for load/resume case, and the display power well
itself being what we need for vlv_display_power_well_init()).

Signed-off-by: Ville Syrjälä <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Reviewed-by: Jani Nikula <[e-mail]>

drivers/gpu/drm/i915/display/intel_display_driver.c

···
 
 	intel_hti_init(display);
 
-	/* Just disable it once at startup */
-	intel_vga_disable(display);
 	intel_setup_outputs(display);
 
 	ret = intel_dp_tunnel_mgr_init(display);
···
 	int ret, i;
 
 	intel_modeset_setup_hw_state(display, ctx);
-	intel_vga_redisable(display);
 
 	if (!state)
 		return 0;

drivers/gpu/drm/i915/display/intel_modeset_setup.c

···
 #include "intel_pmdemand.h"
 #include "intel_tc.h"
 #include "intel_vblank.h"
+#include "intel_vga.h"
 #include "intel_wm.h"
 #include "skl_watermark.h"
 
···
 	wakeref = intel_display_power_get(display, POWER_DOMAIN_INIT);
 
 	intel_early_display_was(display);
+	intel_vga_disable(display);
+
 	intel_modeset_readout_hw_state(display);
 
 	/* HW state is read out, now we need to sanitize this mess. */

drivers/gpu/drm/i915/display/intel_vga.c

···
 	intel_de_posting_read(display, vga_reg);
 }
 
-void intel_vga_redisable(struct intel_display *display)
-{
-	intel_wakeref_t wakeref;
-
-	/*
-	 * This function can be called both from intel_modeset_setup_hw_state or
-	 * at a very early point in our resume sequence, where the power well
-	 * structures are not yet restored. Since this function is at a very
-	 * paranoid "someone might have enabled VGA while we were not looking"
-	 * level, just check if the power well is enabled instead of trying to
-	 * follow the "don't touch the power well if we don't need it" policy
-	 * the rest of the driver uses.
-	 */
-	wakeref = intel_display_power_get_if_enabled(display, POWER_DOMAIN_VGA);
-	if (!wakeref)
-		return;
-
-	intel_vga_disable(display);
-
-	intel_display_power_put(display, POWER_DOMAIN_VGA, wakeref);
-}
-
 void intel_vga_reset_io_mem(struct intel_display *display)
 {
 	struct pci_dev *pdev = to_pci_dev(display->drm->dev);

drivers/gpu/drm/i915/display/intel_vga.h

···
 
 void intel_vga_reset_io_mem(struct intel_display *display);
 void intel_vga_disable(struct intel_display *display);
-void intel_vga_redisable(struct intel_display *display);
 int intel_vga_register(struct intel_display *display);
 void intel_vga_unregister(struct intel_display *display);
 

drivers/gpu/drm/i915/i915_driver.c

···
 #include "display/intel_pch_refclk.h"
 #include "display/intel_pps.h"
 #include "display/intel_sprite_uapi.h"
-#include "display/intel_vga.h"
 #include "display/skl_watermark.h"
 
 #include "gem/i915_gem_context.h"
···
 	intel_dmc_resume(display);
 
 	i9xx_display_sr_restore(display);
-
-	intel_vga_redisable(display);
 
 	intel_gmbus_reset(display);