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Subject[PATCH v5 4/6] drm: rcar-du: lvds: Allow for even and odd pixels swap
Date
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.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>

---
v4->v5:
* Addressed comments from Laurent's review

v3->v4:
* New patch extracted from patch:
"drm: rcar-du: lvds: Add dual-LVDS panels support"
---
drivers/gpu/drm/rcar-du/rcar_lvds.c | 67 +++++++++++++++++++++++++++++--------
1 file changed, 53 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
index 3eb208e..c6a38c3 100644
--- 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 dual_link;
};

#define bridge_to_rcar_lvds(b) \
@@ -484,12 +490,31 @@ 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->dual_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->dual_link ==
+ 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);
}

/*
@@ -716,15 +741,26 @@ 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->dual_link = RCAR_LVDS_DUAL_LINK_ODD_EVEN_PIXELS;
+ break;
+ case DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS:
+ lvds->dual_link = 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->dual_link = RCAR_LVDS_DUAL_LINK_EVEN_ODD_PIXELS;
+ else
+ lvds->dual_link = RCAR_LVDS_SINGLE_LINK;
+ }

if (!lvds->dual_link) {
dev_dbg(dev, "Single-link configuration detected\n");
@@ -741,6 +777,9 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
"Dual-link configuration detected (companion encoder %pOF)\n",
companion);

+ if (lvds->dual_link == 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
@@ -751,7 +790,7 @@ 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->dual_link = lvds->dual_link;

done:
of_node_put(companion);
--
2.7.4
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