drm/i915/skl: Add module parameter to select edp vswing table

This provides an option to override the value set by VBT
for selecting edp Vswing Pre-emph setting table.

v2: Adding comment about this being a temporary workaround and
making the parameter read-only (Jani)
v3: Changing mode to 0400 instead of 0 (Jani)

https://bugs.freedesktop.org/show_bug.cgi?id=89554
Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 51baca1..8136005 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1364,7 +1364,6 @@ struct intel_vbt_data {
        bool edp_initialized;
        bool edp_support;
        int edp_bpp;
-       bool edp_low_vswing;
        struct edp_power_seq edp_pps;
 
        struct {
@@ -1846,6 +1845,8 @@ struct drm_i915_private {
                void (*stop_ring)(struct intel_engine_cs *ring);
        } gt;
 
+       bool edp_low_vswing;
+
        /*
         * NOTE: This is the dri1/ums dungeon, don't add stuff here. Your patch
         * will be rejected. Instead look for a better place.
@@ -2515,6 +2516,7 @@ struct i915_params {
        int mmio_debug;
        bool verbose_state_checks;
        bool nuclear_pageflip;
+       int edp_vswing;
 };
 extern struct i915_params i915 __read_mostly;
 

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index bb64415..8ac5a1b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -53,6 +53,7 @@ struct i915_params i915 __read_mostly = {
        .mmio_debug = 0,
        .verbose_state_checks = 1,
        .nuclear_pageflip = 0,
+       .edp_vswing = 0,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -184,3 +185,10 @@ MODULE_PARM_DESC(verbose_state_checks,
 module_param_named_unsafe(nuclear_pageflip, i915.nuclear_pageflip, bool, 0600);
 MODULE_PARM_DESC(nuclear_pageflip,
                 "Force atomic modeset functionality; only planes work for now (default: false).");
+
+/* WA to get away with the default setting in VBT for early platforms.Will be removed */
+module_param_named_unsafe(edp_vswing, i915.edp_vswing, int, 0400);
+MODULE_PARM_DESC(edp_vswing,
+                "Ignore/Override vswing pre-emph table selection from VBT "
+                "(0=use value from vbt [default], 1=low power swing(200mV),"
+                "2=default swing(400mV))");

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index c08368c..cee596d 100644 (file)
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -672,8 +672,13 @@ parse_edp(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
        if (bdb->version >= 173) {
                uint8_t vswing;
 
-               vswing = (edp->edp_vswing_preemph >> (panel_type * 4)) & 0xF;
-               dev_priv->vbt.edp_low_vswing = vswing == 0;
+               /* Don't read from VBT if module parameter has valid value*/
+               if (i915.edp_vswing) {
+                       dev_priv->edp_low_vswing = i915.edp_vswing == 1;
+               } else {
+                       vswing = (edp->edp_vswing_preemph >> (panel_type * 4)) & 0xF;
+                       dev_priv->edp_low_vswing = vswing == 0;
+               }
        }
 }
 

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index d5bee8b..b8eabc6 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -282,7 +282,7 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port,
                ddi_translations_fdi = NULL;
                ddi_translations_dp = skl_ddi_translations_dp;
                n_dp_entries = ARRAY_SIZE(skl_ddi_translations_dp);
-               if (dev_priv->vbt.edp_low_vswing) {
+               if (dev_priv->edp_low_vswing) {
                        ddi_translations_edp = skl_ddi_translations_edp;
                        n_edp_entries = ARRAY_SIZE(skl_ddi_translations_edp);
                } else {

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 5e978d6..91c8bf3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2894,7 +2894,7 @@ intel_dp_voltage_max(struct intel_dp *intel_dp)
        if (IS_BROXTON(dev))
                return DP_TRAIN_VOLTAGE_SWING_LEVEL_3;
        else if (INTEL_INFO(dev)->gen >= 9) {
-               if (dev_priv->vbt.edp_low_vswing && port == PORT_A)
+               if (dev_priv->edp_low_vswing && port == PORT_A)
                        return DP_TRAIN_VOLTAGE_SWING_LEVEL_3;
                return DP_TRAIN_VOLTAGE_SWING_LEVEL_2;
        } else if (IS_VALLEYVIEW(dev))