[PATCH v2] drm/i915/display: Add quirk to force backlight type on some TUXEDO devices

[Werner Sembach <wse@tuxedocomputers.com>]

The display backlight on TUXEDO DX1708 and InsanityBook 15 v1 with panels
AUO 12701 and AUO 12701 must be forced to INTEL_DP_AUX_BACKLIGHT_ON to be
able to control the brightness.

This could already be archived via a module parameter, but this patch adds
a quirk to apply this by default on the mentioned devices.

This patch does not actually test for the exact panels as the id that is
used in the intel_dpcd_quirks list is sadly zeroed on the devices, but
afaik all these devices use try_intel_interface first anyway so all the
quirk does is to add the fallback to try_vesa_interface, so the behaviour
on the devices not needing the quirk and fallback should functionally stay
the same.

Cc: stable@vger.kernel.org
Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
---
 .../drm/i915/display/intel_dp_aux_backlight.c |  9 ++++++-
 drivers/gpu/drm/i915/display/intel_quirks.c   | 25 ++++++++++++++++++-
 drivers/gpu/drm/i915/display/intel_quirks.h   |  1 +
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index 0a3a3f6a5f9d8..bbdfa142d084d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -41,6 +41,7 @@
 #include "intel_display_types.h"
 #include "intel_dp.h"
 #include "intel_dp_aux_backlight.h"
+#include "intel_quirks.h"
 
 /*
  * DP AUX registers for Intel's proprietary HDR backlight interface. We define
@@ -661,11 +662,17 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
 	struct drm_device *dev = connector->base.dev;
 	struct intel_panel *panel = &connector->panel;
 	bool try_intel_interface = false, try_vesa_interface = false;
+	int enable_dpcd_backlight;
 
 	/* Check the VBT and user's module parameters to figure out which
 	 * interfaces to probe
 	 */
-	switch (display->params.enable_dpcd_backlight) {
+	enable_dpcd_backlight = display->params.enable_dpcd_backlight;
+	if (enable_dpcd_backlight == INTEL_DP_AUX_BACKLIGHT_AUTO &&
+	    intel_has_dpcd_quirk(intel_dp, QUIRK_ENABLE_DPCD_BACKLIGHT))
+		enable_dpcd_backlight = INTEL_DP_AUX_BACKLIGHT_ON;
+
+	switch (enable_dpcd_backlight) {
 	case INTEL_DP_AUX_BACKLIGHT_OFF:
 		return -ENODEV;
 	case INTEL_DP_AUX_BACKLIGHT_AUTO:
diff --git a/drivers/gpu/drm/i915/display/intel_quirks.c b/drivers/gpu/drm/i915/display/intel_quirks.c
index d2e16b79d6be1..df20930f73f75 100644
--- a/drivers/gpu/drm/i915/display/intel_quirks.c
+++ b/drivers/gpu/drm/i915/display/intel_quirks.c
@@ -86,6 +86,14 @@ static void quirk_edp_limit_rate_hbr2(struct intel_display *display)
 	drm_info(display->drm, "Applying eDP Limit rate to HBR2 quirk\n");
 }
 
+static void quirk_enable_dpcd_backlight(struct intel_dp *intel_dp)
+{
+	struct intel_display *display = to_intel_display(intel_dp);
+
+	intel_set_dpcd_quirk(intel_dp, QUIRK_ENABLE_DPCD_BACKLIGHT);
+	drm_info(display->drm, "Applying Enable DPCD Backlight quirk\n");
+}
+
 struct intel_quirk {
 	int device;
 	int subsystem_vendor;
@@ -251,7 +259,22 @@ static const struct intel_dpcd_quirk intel_dpcd_quirks[] = {
 		.sink_oui = SINK_OUI(0x38, 0xec, 0x11),
 		.hook = quirk_fw_sync_len,
 	},
-
+	/* TUXEDO InsanityBook 15 v1 */
+	{
+		.device = 0x591b,
+		.subsystem_vendor = 0x1558,
+		.subsystem_device = 0x9501,
+		.sink_oui = SINK_OUI(0x38, 0xec, 0x11),
+		.hook = quirk_enable_dpcd_backlight,
+	},
+	/* TUXEDO DX1708 */
+	{
+		.device = 0x3e9b,
+		.subsystem_vendor = 0x1558,
+		.subsystem_device = 0x8500,
+		.sink_oui = SINK_OUI(0x38, 0xec, 0x11),
+		.hook = quirk_enable_dpcd_backlight,
+	},
 };
 
 void intel_init_quirks(struct intel_display *display)
diff --git a/drivers/gpu/drm/i915/display/intel_quirks.h b/drivers/gpu/drm/i915/display/intel_quirks.h
index 06da0e286c67c..686f306ab4472 100644
--- a/drivers/gpu/drm/i915/display/intel_quirks.h
+++ b/drivers/gpu/drm/i915/display/intel_quirks.h
@@ -21,6 +21,7 @@ enum intel_quirk_id {
 	QUIRK_NO_PPS_BACKLIGHT_POWER_HOOK,
 	QUIRK_FW_SYNC_LEN,
 	QUIRK_EDP_LIMIT_RATE_HBR2,
+	QUIRK_ENABLE_DPCD_BACKLIGHT,
 };
 
 void intel_init_quirks(struct intel_display *display);
-- 
2.43.0