From: Jernej Skrabec <jernej.skrabec@siol.net>
To: maxime.ripard@bootlin.com
Cc: airlied@linux.ie, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, wens@csie.org,
stable@vger.kernel.org, daniel@ffwll.ch,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH] drm/sun4i: DW HDMI: Lower max. supported rate for H6
Date: Sun, 24 Mar 2019 20:06:09 +0100 [thread overview]
Message-ID: <20190324190609.32721-1-jernej.skrabec@siol.net> (raw)
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
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next reply other threads:[~2019-03-24 19:06 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-24 19:06 Jernej Skrabec [this message]
2019-04-05 8:44 ` [PATCH] drm/sun4i: DW HDMI: Lower max. supported rate for H6 Maxime Ripard
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