[RFC 0/1] drm/exynos: hack to support more HDMI resolutions

[RFC 0/1] drm/exynos: hack to support more HDMI resolutions

[Tobias Jakobi]

Hello,

I was asked by a user of my kernel tree to try to upstream this. The patch is originally by Daniel who figured out this peculiar behaviour of the HDMI block.

Since this is clearly a hack, should it even be upstreamed?

Some more questions/thoughts:
- I know that it works for the HDMI block on the Exynos4412, but I guess it could also work for other Exynos SoCs. So this would require some testing by someone who has access to other boards.
- Currently the manipulation in hdmi_v14_mode_apply() is always active. Once we figure out for which hw the hack works, we could probably set a flag somewhere.
- Same goes for mixer_atomic_check() which now always accepts 1024x768 and 1280x1024. This should also depend on a flag (maybe some CRTC flag).

Feedback would be appreciated!

With best wishes,
Tobias

Daniel Drake (1):
  drm/exynos/hdmi: add 257px offset timing hack

 drivers/gpu/drm/exynos/exynos_hdmi.c  | 16 ++++++++++++----
 drivers/gpu/drm/exynos/exynos_mixer.c |  6 ++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

-- 
2.13.5

[RFC 1/1] drm/exynos/hdmi: add 257px offset timing hack

[Tobias Jakobi]

From: Daniel Drake <drake@endlessm.com>

As discussed in
http://www.spinics.net/lists/linux-samsung-soc/msg24617.html
the 1024x768 timings don't quite work out of the box, for unknown reasons.

However, massaging of the values in the way implemented in this patch
makes the system usable, although it is missing the top row of pixels,
and the rightmost column too.

Apply the timing hack to both 1280x1024 and 1024x768.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
---
 drivers/gpu/drm/exynos/exynos_hdmi.c  | 16 ++++++++++++----
 drivers/gpu/drm/exynos/exynos_mixer.c |  6 ++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
index d5e923452121..2b14cc7def6f 100644
--- a/drivers/gpu/drm/exynos/exynos_hdmi.c
+++ b/drivers/gpu/drm/exynos/exynos_hdmi.c
@@ -1241,6 +1241,14 @@ static void hdmi_v13_mode_apply(struct hdmi_context *hdata)
 static void hdmi_v14_mode_apply(struct hdmi_context *hdata)
 {
 	struct drm_display_mode *m = &hdata->current_mode;
+	int hcorrect = 0;
+	int vcorrect = 0;
+
+	if ((m->hdisplay == 1024 && m->vdisplay == 768) ||
+	    (m->hdisplay == 1280 && m->vdisplay == 1024)) {
+		hcorrect = 257;
+		vcorrect = 1;
+	}
 
 	hdmi_reg_writev(hdata, HDMI_H_BLANK_0, 2, m->htotal - m->hdisplay);
 	hdmi_reg_writev(hdata, HDMI_V_LINE_0, 2, m->vtotal);
@@ -1306,8 +1314,8 @@ static void hdmi_v14_mode_apply(struct hdmi_context *hdata)
 		hdmi_reg_writev(hdata, HDMI_V_SYNC_LINE_AFT_PXL_2_0, 2, 0xffff);
 		hdmi_reg_writev(hdata, HDMI_V_SYNC_LINE_AFT_PXL_1_0, 2, 0xffff);
 		hdmi_reg_writev(hdata, HDMI_TG_VACT_ST_L, 2,
-				m->vtotal - m->vdisplay);
-		hdmi_reg_writev(hdata, HDMI_TG_VACT_SZ_L, 2, m->vdisplay);
+				(m->vtotal - m->vdisplay) - vcorrect);
+		hdmi_reg_writev(hdata, HDMI_TG_VACT_SZ_L, 2, m->vdisplay + vcorrect);
 	}
 
 	hdmi_reg_writev(hdata, HDMI_H_SYNC_START_0, 2,
@@ -1334,8 +1342,8 @@ static void hdmi_v14_mode_apply(struct hdmi_context *hdata)
 	hdmi_reg_writev(hdata, HDMI_V_SYNC_LINE_AFT_PXL_6_0, 2, 0xffff);
 
 	hdmi_reg_writev(hdata, HDMI_TG_H_FSZ_L, 2, m->htotal);
-	hdmi_reg_writev(hdata, HDMI_TG_HACT_ST_L, 2, m->htotal - m->hdisplay);
-	hdmi_reg_writev(hdata, HDMI_TG_HACT_SZ_L, 2, m->hdisplay);
+	hdmi_reg_writev(hdata, HDMI_TG_HACT_ST_L, 2, (m->htotal - m->hdisplay) - hcorrect);
+	hdmi_reg_writev(hdata, HDMI_TG_HACT_SZ_L, 2, m->hdisplay + hcorrect);
 	hdmi_reg_writev(hdata, HDMI_TG_V_FSZ_L, 2, m->vtotal);
 	if (hdata->drv_data == &exynos5433_hdmi_driver_data)
 		hdmi_reg_writeb(hdata, HDMI_TG_DECON_EN, 1);
diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
index 600b4de45c51..96c3f61f080e 100644
--- a/drivers/gpu/drm/exynos/exynos_mixer.c
+++ b/drivers/gpu/drm/exynos/exynos_mixer.c
@@ -1119,11 +1119,17 @@ static int mixer_atomic_check(struct exynos_drm_crtc *crtc,
 		mode->hdisplay, mode->vdisplay, mode->vrefresh,
 		(mode->flags & DRM_MODE_FLAG_INTERLACE) ? 1 : 0);
 
+	/* Check against resolution ranges. */
 	if ((w >= 464 && w <= 720 && h >= 261 && h <= 576) ||
 		(w >= 1024 && w <= 1280 && h >= 576 && h <= 720) ||
 		(w >= 1664 && w <= 1920 && h >= 936 && h <= 1080))
 		return 0;
 
+	/* Check against some specific resolutions. */
+	if ((w == 1024 && h == 768) ||
+		(w == 1280 && h == 1024))
+		return 0;
+
 	return -EINVAL;
 }
 
-- 
2.13.5