drm/i915/dp: Add dpcd link_rate quirk for Apple 15" MBP 2017 (v3)

This fixes a problem found on the MacBookPro 2017 Retina panel.

The panel reports 10 bpc color depth in its EDID, and the
firmware chooses link settings at boot which support enough
bandwidth for 10 bpc (324000 kbit/sec = multiplier 0xc),
but the DP_MAX_LINK_RATE dpcd register only reports
2.7 Gbps (multiplier value 0xa) as possible, in direct
contradiction of what the firmware successfully set up.

This restricts the panel to 8 bpc, not providing the full
color depth of the panel.

This patch adds a quirk specific to the MBP 2017 15" Retina
panel to add the additiional 324000 kbps link rate during
edp setup.

Link to previous discussion of a different attempted fix
with Ville and Jani:

https://patchwork.kernel.org/patch/11325935/

v2: Follow Jani's proposal of defining quirk_rates[] instead
    of just appending 324000. This for better clarity.

v3: Rebased onto current drm-tip, as of 16-March-2020. Adapt
    to new edid_quirks parameter of drm_dp_has_quirk().

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Tested-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200316042340.4783-1-mario.kleiner.de@gmail.com

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 620d78ff27063cd32933798b53d500a55ecbc067..688c475d52b5fea8b49dbd2d2418631385cf5342 100644 (file)
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -1179,6 +1179,8 @@ static const struct dpcd_quirk dpcd_quirk_list[] = {
        { OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) },
        /* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */
        { OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) },
+       /* Apple MacBookPro 2017 15 inch eDP Retina panel reports too low DP_MAX_LINK_RATE */
+       { OUI(0x00, 0x10, 0xfa), DEVICE_ID(101, 68, 21, 101, 98, 97), false, BIT(DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS) },
 };
 
 #undef OUI

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 0a417cd2af2bc02dd8f992b28b6b810c6f3e2232..ef2e06e292d5fe029163f3154fd1099be11be15c 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -164,6 +164,17 @@ static void intel_dp_set_sink_rates(struct intel_dp *intel_dp)
        };
        int i, max_rate;
 
+       if (drm_dp_has_quirk(&intel_dp->desc, 0,
+                            DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS)) {
+               /* Needed, e.g., for Apple MBP 2017, 15 inch eDP Retina panel */
+               static const int quirk_rates[] = { 162000, 270000, 324000 };
+
+               memcpy(intel_dp->sink_rates, quirk_rates, sizeof(quirk_rates));
+               intel_dp->num_sink_rates = ARRAY_SIZE(quirk_rates);
+
+               return;
+       }
+
        max_rate = drm_dp_bw_code_to_link_rate(intel_dp->dpcd[DP_MAX_LINK_RATE]);
 
        for (i = 0; i < ARRAY_SIZE(dp_rates); i++) {

diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index c5580e9888267e2d9821ca514d3ede97144f14b1..4cc4133853c854e50f65ef981970e94b749e652e 100644 (file)
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1545,6 +1545,13 @@ enum drm_dp_quirk {
         * capabilities advertised.
         */
        DP_QUIRK_FORCE_DPCD_BACKLIGHT,
+       /**
+        * @DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS:
+        *
+        * The device supports a link rate of 3.24 Gbps (multiplier 0xc) despite
+        * the DP_MAX_LINK_RATE register reporting a lower max multiplier.
+        */
+       DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS,
 };
 
 /**