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* [PATCH] drm/sun4i: DW HDMI: Lower max. supported rate for H6
@ 2019-03-24 19:06 Jernej Skrabec
  2019-04-05  8:44 ` Maxime Ripard
  0 siblings, 1 reply; 2+ messages in thread
From: Jernej Skrabec @ 2019-03-24 19:06 UTC (permalink / raw)
  To: maxime.ripard
  Cc: airlied, daniel, wens, dri-devel, linux-arm-kernel, linux-kernel, stable

Currently resolutions with pixel clock higher than 340 MHz don't work
with H6 HDMI controller. They just produce a blank screen.

Limit maximum pixel clock rate to 340 MHz until scrambling is supported.

Cc: stable@vger.kernel.org # 5.0
Fixes: 40bb9d3147b2 ("drm/sun4i: Add support for H6 DW HDMI controller")
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
---
 drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
index caea5a9f8f1d..ba4ce576b471 100644
--- a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
+++ b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
@@ -48,8 +48,13 @@ static enum drm_mode_status
 sun8i_dw_hdmi_mode_valid_h6(struct drm_connector *connector,
 			    const struct drm_display_mode *mode)
 {
-	/* This is max for HDMI 2.0b (4K@60Hz) */
-	if (mode->clock > 594000)
+	/*
+	 * Controller support maximum of 594 MHz, which correlates to
+	 * 4K@60Hz 4:4:4 or RGB. However, for frequencies greater than
+	 * 340 MHz scrambling has to be enabled. Because scrambling is
+	 * not yet implemented, just limit to 340 MHz for now.
+	 */
+	if (mode->clock > 340000)
 		return MODE_CLOCK_HIGH;
 
 	return MODE_OK;
-- 
2.21.0


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] drm/sun4i: DW HDMI: Lower max. supported rate for H6
  2019-03-24 19:06 [PATCH] drm/sun4i: DW HDMI: Lower max. supported rate for H6 Jernej Skrabec
@ 2019-04-05  8:44 ` Maxime Ripard
  0 siblings, 0 replies; 2+ messages in thread
From: Maxime Ripard @ 2019-04-05  8:44 UTC (permalink / raw)
  To: Jernej Skrabec
  Cc: airlied, daniel, wens, dri-devel, linux-arm-kernel, linux-kernel, stable

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On Sun, Mar 24, 2019 at 08:06:09PM +0100, Jernej Skrabec wrote:
> Currently resolutions with pixel clock higher than 340 MHz don't work
> with H6 HDMI controller. They just produce a blank screen.
>
> Limit maximum pixel clock rate to 340 MHz until scrambling is supported.
>
> Cc: stable@vger.kernel.org # 5.0
> Fixes: 40bb9d3147b2 ("drm/sun4i: Add support for H6 DW HDMI controller")
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>

Applied, thanks!

(And sorry for the delay)

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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^ permalink raw reply	[flat|nested] 2+ messages in thread

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