drm/i915/ehl: Add support for DPLL4 (v10)

This patch adds support for DPLL4 on EHL that include the
following restrictions:

- DPLL4 cannot be used with DDIA (combo port A internal eDP usage).
  DPLL4 can be used with other DDIs, including DDID
  (combo port A external usage).

- DPLL4 cannot be enabled when DC5 or DC6 are enabled.

- The DPLL4 enable, lock, power enabled, and power state are connected
  to the MGPLL1_ENABLE register.

v2: (suggestions from Bob Paauwe)
- Rework ehl_get_dpll() function to call intel_find_shared_dpll() and
  iterate twice: once for Combo plls and once for MG plls.

- Use MG pll funcs for DPLL4 instead of creating new ones and modify
  mg_pll_enable to include the restrictions for EHL.

v3: Fix compilation error

v4: (suggestions from Lucas and Ville)
- Treat DPLL4 as a combo phy PLL and not as MG PLL
- Disable DC states when this DPLL is being enabled
- Reuse icl_get_dpll instead of creating a separate one for EHL

v5: (suggestion from Ville)
- Refcount the DC OFF power domains during the enabling and disabling
  of this DPLL.

v6: rebase

v7: (suggestion from Imre)
- Add a new power domain instead of iterating over the domains
  assoicated with DC OFF power well.

v8: (Ville and Imre)
- Rename POWER_DOMAIN_DPLL4 TO POWER_DOMAIN_DPLL_DC_OFF
- Grab a reference in intel_modeset_setup_hw_state() if this
  DPLL was already enabled perhaps by BIOS.
- Check for the port type instead of the encoder

v9: (Ville)
- Move the block of code that grabs a reference to the power domain
  POWER_DOMAIN_DPLL_DC_OFF to intel_modeset_readout_hw_state() to ensure
  that there is a reference present before this DPLL might get disabled.

v10: rebase

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190703230353.24059-1-vivek.kasireddy@intel.com

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.h b/drivers/gpu/drm/i915/display/intel_dpll_mgr.h
index 1668f8116908..4c2c5e93aff3 100644
--- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.h
+++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.h
@@ -28,6 +28,7 @@
 #include <linux/types.h>
 
 #include "intel_display.h"
+#include "intel_wakeref.h"
 
 /*FIXME: Move this to a more appropriate place. */
 #define abs_diff(a, b) ({			\
@@ -119,6 +120,10 @@ enum intel_dpll_id {
 	 */
 	DPLL_ID_ICL_DPLL1 = 1,
 	/**
+	 * @DPLL_ID_EHL_DPLL4: EHL combo PHY DPLL4
+	 */
+	DPLL_ID_EHL_DPLL4 = 2,
+	/**
 	 * @DPLL_ID_ICL_TBTPLL: ICL TBT PLL
 	 */
 	DPLL_ID_ICL_TBTPLL = 2,
@@ -320,6 +325,7 @@ struct intel_shared_dpll {
 	 * @info: platform specific info
 	 */
 	const struct dpll_info *info;
+	intel_wakeref_t wakeref;
 };
 
 #define SKL_DPLL0 0