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

Sonika Jindal
2015-05-06T12:14:54Z

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>
---
drivers/gpu/drm/i915/i915_drv.h | 4 +++-
drivers/gpu/drm/i915/i915_params.c | 8 ++++++++
drivers/gpu/drm/i915/intel_bios.c | 9 +++++++--
drivers/gpu/drm/i915/intel_ddi.c | 2 +-
drivers/gpu/drm/i915/intel_dp.c | 2 +-
5 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 136d42a..1c3ee66 100644
--- 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
--- 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
--- 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 9c1e74a..2539f22 100644
--- 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 bacdec5..5f53666 100644
--- 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))
--
1.7.10.4