Finding the right input bus format throughout the pipeline is hard
so add atomic_get_input_bus_fmts callback and initialize with the
proper input format from list of supported output formats.

This format can be used in pipeline for negotiating bus format between
the DSI-end of this bridge and the other component closer to pipeline
components.

List of Pixel formats are taken from,
AN13573 i.MX 8/RT MIPI DSI/CSI-2, Rev. 0, 21 March 2022
3.7.4 Pixel formats
Table 14. DSI pixel packing formats

Tested-by: Marek Szyprowski <m.szyprow...@samsung.com>
Signed-off-by: Jagan Teki <ja...@amarulasolutions.com>
---
Changes for v10:
- none
Changes for v9:
- added MEDIA_BUS_FMT_FIXED
- return MEDIA_BUS_FMT_RGB888_1X24 output_fmt if supported output_fmt
  list is unsupported.
- added MEDIA_BUS_FMT_YUYV10_1X20, MEDIA_BUS_FMT_YUYV12_1X24
Changes for v8:
- added pixel formats supported by NXP AN13573 i.MX 8/RT MIPI DSI/CSI-2
Changes for v7 - v4:
- none
Changes for v3:
- include media-bus-format.h
Changes for v2:
- none
Changes for v1:
- new patch

 drivers/gpu/drm/exynos/exynos_drm_dsi.c | 69 +++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c 
b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 36820a7b5884..bb3d6a7fa84e 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -12,6 +12,7 @@
 #include <linux/component.h>
 #include <linux/gpio/consumer.h>
 #include <linux/irq.h>
+#include <linux/media-bus-format.h>
 #include <linux/of_device.h>
 #include <linux/of_graph.h>
 #include <linux/phy/phy.h>
@@ -1467,6 +1468,73 @@ static void exynos_dsi_atomic_post_disable(struct 
drm_bridge *bridge,
        pm_runtime_put_sync(dsi->dev);
 }
 
+/*
+ * This pixel output formats list referenced from,
+ * AN13573 i.MX 8/RT MIPI DSI/CSI-2, Rev. 0, 21 March 2022
+ * 3.7.4 Pixel formats
+ * Table 14. DSI pixel packing formats
+ */
+static const u32 exynos_dsi_pixel_output_fmts[] = {
+       MEDIA_BUS_FMT_YUYV10_1X20,
+       MEDIA_BUS_FMT_YUYV12_1X24,
+       MEDIA_BUS_FMT_UYVY8_1X16,
+       MEDIA_BUS_FMT_RGB101010_1X30,
+       MEDIA_BUS_FMT_RGB121212_1X36,
+       MEDIA_BUS_FMT_RGB565_1X16,
+       MEDIA_BUS_FMT_RGB666_1X18,
+       MEDIA_BUS_FMT_RGB888_1X24,
+
+       MEDIA_BUS_FMT_FIXED,
+};
+
+static bool exynos_dsi_pixel_output_fmt_supported(u32 fmt)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(exynos_dsi_pixel_output_fmts); i++) {
+               if (exynos_dsi_pixel_output_fmts[i] == fmt)
+                       return true;
+       }
+
+       return false;
+}
+
+static u32 *
+exynos_dsi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
+                                    struct drm_bridge_state *bridge_state,
+                                    struct drm_crtc_state *crtc_state,
+                                    struct drm_connector_state *conn_state,
+                                    u32 output_fmt,
+                                    unsigned int *num_input_fmts)
+{
+       u32 *input_fmts;
+
+       if (!exynos_dsi_pixel_output_fmt_supported(output_fmt))
+               /*
+                * Some bridge/display drivers are still not able to pass the
+                * correct format, so handle those pipelines by falling back
+                * to the default format till the supported formats finalized.
+                */
+               output_fmt = MEDIA_BUS_FMT_RGB888_1X24;
+
+       input_fmts = kmalloc(sizeof(*input_fmts), GFP_KERNEL);
+       if (!input_fmts)
+               return NULL;
+
+       switch (output_fmt) {
+       case MEDIA_BUS_FMT_FIXED:
+               input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
+               break;
+       default:
+               input_fmts[0] = output_fmt;
+               break;
+       }
+
+       *num_input_fmts = 1;
+
+       return input_fmts;
+}
+
 static int exynos_dsi_atomic_check(struct drm_bridge *bridge,
                                   struct drm_bridge_state *bridge_state,
                                   struct drm_crtc_state *crtc_state,
@@ -1515,6 +1583,7 @@ static const struct drm_bridge_funcs 
exynos_dsi_bridge_funcs = {
        .atomic_duplicate_state         = 
drm_atomic_helper_bridge_duplicate_state,
        .atomic_destroy_state           = 
drm_atomic_helper_bridge_destroy_state,
        .atomic_reset                   = drm_atomic_helper_bridge_reset,
+       .atomic_get_input_bus_fmts      = exynos_dsi_atomic_get_input_bus_fmts,
        .atomic_check                   = exynos_dsi_atomic_check,
        .atomic_pre_enable              = exynos_dsi_atomic_pre_enable,
        .atomic_enable                  = exynos_dsi_atomic_enable,
-- 
2.25.1

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