[PATCH v6 05/10] drm: bridge: samsung-dsim: Add atomic_check

[Jagan Teki]

Look like an explicit fixing up of mode_flags is required for DSIM IP
present in i.MX8M Mini/Nano SoCs.

At least the LCDIF + DSIM needs active low sync polarities in order
to correlate the correct sync flags of the surrounding components in
the chain to make sure the whole pipeline can work properly.

On the other hand the i.MX 8M Mini Applications Processor Reference Manual,
Rev. 3, 11/2020 says.
"13.6.3.5.2 RGB interface
 Vsync, Hsync, and VDEN are active high signals."

No clear evidence about whether it can be documentation issues or
something, so added a comment FIXME for this and updated the active low
sync polarities using SAMSUNG_DSIM_TYPE_IMX8MM hw_type.

v6:
* none

v5:
* rebase based new bridge changes [mszyprow]
* remove DSIM_QUIRK_FIXUP_SYNC_POL
* add hw_type check for sync polarities change.

v4:
* none

v3:
* add DSIM_QUIRK_FIXUP_SYNC_POL to handle mode_flasg fixup

v2:
* none

v1:
* fix mode flags in atomic_check instead of mode_fixup

Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 0636440e4420..90506be3f2dd 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1315,6 +1315,31 @@ static void samsung_dsim_atomic_post_disable(struct drm_bridge *bridge,
 	pm_runtime_put_sync(dsi->dev);
 }
 
+static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
+				     struct drm_bridge_state *bridge_state,
+				     struct drm_crtc_state *crtc_state,
+				     struct drm_connector_state *conn_state)
+{
+	struct samsung_dsim *dsi = bridge_to_dsi(bridge);
+	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
+
+	if (dsi->plat_data->hw_type & SAMSUNG_DSIM_TYPE_IMX8MM) {
+		/**
+		 * FIXME:
+		 * At least LCDIF + DSIM needs active low sync,
+		 * but i.MX 8M Mini Applications Processor Reference Manual,
+		 * Rev. 3, 11/2020 says
+		 *
+		 * 13.6.3.5.2 RGB interface
+		 * Vsync, Hsync, and VDEN are active high signals.
+		 */
+		adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
+		adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
+	}
+
+	return 0;
+}
+
 static void samsung_dsim_mode_set(struct drm_bridge *bridge,
 				  const struct drm_display_mode *mode,
 				  const struct drm_display_mode *adjusted_mode)
@@ -1353,6 +1378,7 @@ static const struct drm_bridge_funcs samsung_dsim_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_check			= samsung_dsim_atomic_check,
 	.atomic_pre_enable		= samsung_dsim_atomic_pre_enable,
 	.atomic_enable			= samsung_dsim_atomic_enable,
 	.atomic_disable			= samsung_dsim_atomic_disable,
-- 
2.25.1