[PATCH 8/8] drm/tilcdc fixup mode to workaound sync for tda998x

From: Sebastian Hesselbarth
Date: Mon Aug 05 2013 - 18:21:05 EST


From: Darren Etheridge <detheridge@xxxxxx>

Add a fixup function that will flip the hsync priority and
add a hskew value that is used to shift the tda998x to the
right by a variable number of pixels depending on the mode.
This works around an issue with the sync timings that tilcdc
is outputing.

Signed-off-by: Darren Etheridge <detheridge@xxxxxx>
---
Changelog:
for v1:
- reword comment

Cc: David Airlie <airlied@xxxxxxxx>
Cc: Darren Etheridge <detheridge@xxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 7 ++++++-
drivers/gpu/drm/tilcdc/tilcdc_slave.c | 27 ++++++++++++++++++++++++++-
2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 7418dcd..6d05240 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -379,7 +379,12 @@ static int tilcdc_crtc_mode_set(struct drm_crtc *crtc,
else
tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG, LCDC_SYNC_EDGE);

- if (mode->flags & DRM_MODE_FLAG_NHSYNC)
+ /*
+ * use value from adjusted_mode here as this might have been
+ * changed as part of the fixup for slave encoders to solve the
+ * issue where tilcdc timings are not VESA compliant
+ */
+ if (adjusted_mode->flags & DRM_MODE_FLAG_NHSYNC)
tilcdc_set(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_HSYNC);
else
tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_HSYNC);
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_slave.c b/drivers/gpu/drm/tilcdc/tilcdc_slave.c
index 0bf5999..f6e9c26 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_slave.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_slave.c
@@ -73,13 +73,38 @@ static void slave_encoder_prepare(struct drm_encoder *encoder)
tilcdc_crtc_set_panel_info(encoder->crtc, &slave_info);
}

+static bool slave_encoder_fixup(struct drm_encoder *encoder,
+ const struct drm_display_mode *mode,
+ struct drm_display_mode *adjusted_mode)
+{
+ /*
+ * tilcdc does not generate VESA-complient sync but aligns
+ * VS on the second edge of HS instead of first edge.
+ * We use adjusted_mode, to fixup sync by aligning both rising
+ * edges and add HSKEW offset to let the slave encoder fix it up.
+ */
+ adjusted_mode->hskew = mode->hsync_end - mode->hsync_start;
+ adjusted_mode->flags |= DRM_MODE_FLAG_HSKEW;
+
+ if (mode->flags & DRM_MODE_FLAG_NHSYNC) {
+ adjusted_mode->flags |= DRM_MODE_FLAG_PHSYNC;
+ adjusted_mode->flags &= ~DRM_MODE_FLAG_NHSYNC;
+ } else {
+ adjusted_mode->flags |= DRM_MODE_FLAG_NHSYNC;
+ adjusted_mode->flags &= ~DRM_MODE_FLAG_PHSYNC;
+ }
+
+ return drm_i2c_encoder_mode_fixup(encoder, mode, adjusted_mode);
+}
+
+
static const struct drm_encoder_funcs slave_encoder_funcs = {
.destroy = slave_encoder_destroy,
};

static const struct drm_encoder_helper_funcs slave_encoder_helper_funcs = {
.dpms = drm_i2c_encoder_dpms,
- .mode_fixup = drm_i2c_encoder_mode_fixup,
+ .mode_fixup = slave_encoder_fixup,
.prepare = slave_encoder_prepare,
.commit = drm_i2c_encoder_commit,
.mode_set = drm_i2c_encoder_mode_set,
--
1.7.10.4

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