Some panels support multiple LVDS data mapping formats, which can be
used e.g. run displays on jeida-18 format when only 3 LVDS lanes are
available.

Add parsing of an optional data-mapping devicetree property, which also
touches up the bits per color to match the bus format.

Signed-off-by: Johannes Zink <j.z...@pengutronix.de>

---

Changes:

  v1 -> v2: - fix missing unwind goto found by test robot
              Reported-by: kernel test robot <l...@intel.com>
              Reported-by: Dan Carpenter <erro...@gmail.com>
              Link: 
https://lore.kernel.org/r/202304160359.4lhmfolu-...@intel.com/
---
 drivers/gpu/drm/panel/panel-simple.c | 39 +++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c 
b/drivers/gpu/drm/panel/panel-simple.c
index 2a9c1a785a5c..0a35fdb49ccb 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -40,6 +40,7 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_mipi_dsi.h>
 #include <drm/drm_panel.h>
+#include <drm/drm_of.h>
 
 /**
  * struct panel_desc - Describes a simple panel.
@@ -559,7 +560,7 @@ static int panel_simple_probe(struct device *dev, const 
struct panel_desc *desc)
        struct device_node *ddc;
        int connector_type;
        u32 bus_flags;
-       int err;
+       int err, ret;
 
        panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
        if (!panel)
@@ -605,6 +606,42 @@ static int panel_simple_probe(struct device *dev, const 
struct panel_desc *desc)
                        panel_simple_parse_panel_timing_node(dev, panel, &dt);
        }
 
+
+       /* optional data-mapping property for overriding bus format */
+       ret = drm_of_lvds_get_data_mapping(dev->of_node);
+       if (ret == -EINVAL) {
+               dev_warn(dev, "Ignore invalid data-mapping property");
+       } else if (ret != -ENODEV) {
+               int bpc;
+
+               switch (ret) {
+               default:
+                       WARN_ON(1);
+                       fallthrough;
+               case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
+                       fallthrough;
+               case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
+                       bpc = 8;
+                       break;
+               case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+                       bpc = 6;
+               }
+
+               if (desc->bpc != bpc || desc->bus_format != ret) {
+                       struct panel_desc *override_desc;
+
+                       override_desc = devm_kmemdup(dev, desc, sizeof(*desc), 
GFP_KERNEL);
+                       if (!override_desc) {
+                               err = -ENOMEM;
+                               goto free_ddc;
+                       }
+
+                       override_desc->bus_format = ret;
+                       override_desc->bpc = bpc;
+                       panel->desc = override_desc;
+               }
+       }
+
        connector_type = desc->connector_type;
        /* Catch common mistakes for panels. */
        switch (connector_type) {

-- 
2.39.2

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