drm: rcar-du: lvds: Allow for even and odd pixels swap

DT properties dual-lvds-even-pixels and dual-lvds-odd-pixels
can be used to work out if the driver needs to swap even
and odd pixels around.

This patch makes use of the return value from function
drm_of_lvds_get_dual_link_pixel_order to determine if we
need to swap odd and even pixels around for things to work
properly.

The dual_link boolean field from struct rcar_lvds is not
sufficient to describe the type of LVDS link anymore, since
we now have information related to pixel order, therefore
rename it to link_type and repurpose its usage to fit the
new requirements.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
index 1749b9c..fd55770 100644 (file)
--- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
+++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
@@ -37,6 +37,12 @@ enum rcar_lvds_mode {
        RCAR_LVDS_MODE_VESA = 4,
 };
 
+enum rcar_lvds_link_type {
+       RCAR_LVDS_SINGLE_LINK = 0,
+       RCAR_LVDS_DUAL_LINK_EVEN_ODD_PIXELS = 1,
+       RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS = 2,
+};
+
 #define RCAR_LVDS_QUIRK_LANES          BIT(0)  /* LVDS lanes 1 and 3 inverted */
 #define RCAR_LVDS_QUIRK_GEN3_LVEN      BIT(1)  /* LVEN bit needs to be set on R8A77970/R8A7799x */
 #define RCAR_LVDS_QUIRK_PWD            BIT(2)  /* PWD bit available (all of Gen3 but E3) */
@@ -67,7 +73,7 @@ struct rcar_lvds {
        } clocks;
 
        struct drm_bridge *companion;
-       bool dual_link;
+       enum rcar_lvds_link_type link_type;
 };
 
 #define bridge_to_rcar_lvds(b) \
@@ -456,7 +462,7 @@ static void __rcar_lvds_atomic_enable(struct drm_bridge *bridge,
                return;
 
        /* Enable the companion LVDS encoder in dual-link mode. */
-       if (lvds->dual_link && lvds->companion)
+       if (lvds->link_type != RCAR_LVDS_SINGLE_LINK && lvds->companion)
                __rcar_lvds_atomic_enable(lvds->companion, state, crtc,
                                          connector);
 
@@ -482,19 +488,38 @@ static void __rcar_lvds_atomic_enable(struct drm_bridge *bridge,
        rcar_lvds_write(lvds, LVDCHCR, lvdhcr);
 
        if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK) {
-               /*
-                * Configure vertical stripe based on the mode of operation of
-                * the connected device.
-                */
-               rcar_lvds_write(lvds, LVDSTRIPE,
-                               lvds->dual_link ? LVDSTRIPE_ST_ON : 0);
+               u32 lvdstripe = 0;
+
+               if (lvds->link_type != RCAR_LVDS_SINGLE_LINK) {
+                       /*
+                        * By default we generate even pixels from the primary
+                        * encoder and odd pixels from the companion encoder.
+                        * Swap pixels around if the sink requires odd pixels
+                        * from the primary encoder and even pixels from the
+                        * companion encoder.
+                        */
+                       bool swap_pixels = lvds->link_type ==
+                               RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS;
+
+                       /*
+                        * Configure vertical stripe since we are dealing with
+                        * an LVDS dual-link connection.
+                        *
+                        * ST_SWAP is reserved for the companion encoder, only
+                        * set it in the primary encoder.
+                        */
+                       lvdstripe = LVDSTRIPE_ST_ON
+                                 | (lvds->companion && swap_pixels ?
+                                    LVDSTRIPE_ST_SWAP : 0);
+               }
+               rcar_lvds_write(lvds, LVDSTRIPE, lvdstripe);
        }
 
        /*
         * PLL clock configuration on all instances but the companion in
         * dual-link mode.
         */
-       if (!lvds->dual_link || lvds->companion) {
+       if (lvds->link_type == RCAR_LVDS_SINGLE_LINK || lvds->companion) {
                const struct drm_crtc_state *crtc_state =
                        drm_atomic_get_new_crtc_state(state, crtc);
                const struct drm_display_mode *mode =
@@ -592,7 +617,7 @@ static void rcar_lvds_atomic_disable(struct drm_bridge *bridge,
        rcar_lvds_write(lvds, LVDPLLCR, 0);
 
        /* Disable the companion LVDS encoder in dual-link mode. */
-       if (lvds->dual_link && lvds->companion)
+       if (lvds->link_type != RCAR_LVDS_SINGLE_LINK && lvds->companion)
                lvds->companion->funcs->atomic_disable(lvds->companion, state);
 
        clk_disable_unprepare(lvds->clocks.mod);
@@ -666,7 +691,7 @@ bool rcar_lvds_dual_link(struct drm_bridge *bridge)
 {
        struct rcar_lvds *lvds = bridge_to_rcar_lvds(bridge);
 
-       return lvds->dual_link;
+       return lvds->link_type != RCAR_LVDS_SINGLE_LINK;
 }
 EXPORT_SYMBOL_GPL(rcar_lvds_dual_link);
 
@@ -712,17 +737,28 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
        of_node_put(port0);
        of_node_put(port1);
 
-       if (dual_link >= DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS)
-               lvds->dual_link = true;
-       else if (lvds->next_bridge && lvds->next_bridge->timings)
+       switch (dual_link) {
+       case DRM_LVDS_DUAL_LINK_ODD_EVEN_PIXELS:
+               lvds->link_type = RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS;
+               break;
+       case DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS:
+               lvds->link_type = RCAR_LVDS_DUAL_LINK_EVEN_ODD_PIXELS;
+               break;
+       default:
                /*
                 * Early dual-link bridge specific implementations populate the
-                * timings field of drm_bridge, read the dual_link flag off the
-                * bridge directly for backward compatibility.
+                * timings field of drm_bridge. If the flag is set, we assume
+                * that we are expected to generate even pixels from the primary
+                * encoder, and odd pixels from the companion encoder.
                 */
-               lvds->dual_link = lvds->next_bridge->timings->dual_link;
+               if (lvds->next_bridge && lvds->next_bridge->timings &&
+                   lvds->next_bridge->timings->dual_link)
+                       lvds->link_type = RCAR_LVDS_DUAL_LINK_EVEN_ODD_PIXELS;
+               else
+                       lvds->link_type = RCAR_LVDS_SINGLE_LINK;
+       }
 
-       if (!lvds->dual_link) {
+       if (lvds->link_type == RCAR_LVDS_SINGLE_LINK) {
                dev_dbg(dev, "Single-link configuration detected\n");
                goto done;
        }
@@ -737,6 +773,9 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
                "Dual-link configuration detected (companion encoder %pOF)\n",
                companion);
 
+       if (lvds->link_type == RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS)
+               dev_dbg(dev, "Data swapping required\n");
+
        /*
         * FIXME: We should not be messing with the companion encoder private
         * data from the primary encoder, we should rather let the companion
@@ -747,7 +786,7 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
         * for the time being.
         */
        companion_lvds = bridge_to_rcar_lvds(lvds->companion);
-       companion_lvds->dual_link = true;
+       companion_lvds->link_type = lvds->link_type;
 
 done:
        of_node_put(companion);