[PATCH v1 1/2] drm/tegra: dc: rgb: Move PCLK shifter programming to CRTC

[Dmitry Osipenko]

Asus TF700T tablet uses TC358768 DPI->DSI bridge that sits between Tegra's
DPI output and display panel input. Bridge requires to have stable PCLK
output before RGB encoder is enabled because it uses PCLK by itself to
clock internal logic and bridge is programmed before Tegra's encoder is
enabled. Hence the PCLK clock shifter must be programmed when CRTC is
enabled, otherwise clock is unstable and bridge hangs because of it.
Move the shifter programming from RGB encoder into CRTC.

Tested-by: Maxim Schwalm <maxim.schwalm at gmail.com> #TF700T
Signed-off-by: Dmitry Osipenko <digetx at gmail.com>
---
 drivers/gpu/drm/tegra/dc.c  | 6 ++++++
 drivers/gpu/drm/tegra/rgb.c | 4 ----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index a29d64f87563..a582ce28b632 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -2107,6 +2107,12 @@ static void tegra_crtc_atomic_enable(struct drm_crtc *crtc,
 		tegra_dc_writel(dc, value, DC_COM_RG_UNDERFLOW);
 	}
 
+	if (dc->rgb) {
+		/* XXX: parameterize? */
+		value = SC0_H_QUALIFIER_NONE | SC1_H_QUALIFIER_NONE;
+		tegra_dc_writel(dc, value, DC_DISP_SHIFT_CLOCK_OPTIONS);
+	}
+
 	tegra_dc_commit(dc);
 
 	drm_crtc_vblank_on(crtc);
diff --git a/drivers/gpu/drm/tegra/rgb.c b/drivers/gpu/drm/tegra/rgb.c
index 606c78a2b988..933e14e4609f 100644
--- a/drivers/gpu/drm/tegra/rgb.c
+++ b/drivers/gpu/drm/tegra/rgb.c
@@ -116,10 +116,6 @@ static void tegra_rgb_encoder_enable(struct drm_encoder *encoder)
 		DISP_ORDER_RED_BLUE;
 	tegra_dc_writel(rgb->dc, value, DC_DISP_DISP_INTERFACE_CONTROL);
 
-	/* XXX: parameterize? */
-	value = SC0_H_QUALIFIER_NONE | SC1_H_QUALIFIER_NONE;
-	tegra_dc_writel(rgb->dc, value, DC_DISP_SHIFT_CLOCK_OPTIONS);
-
 	tegra_dc_commit(rgb->dc);
 }
 
-- 
2.32.0