hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

drm/sun4i: validate modes for HDMI 

When I connected my cubieboard running 4.15-rc1 to my 4k display I got no
picture. Some digging found that there is no check against the upper
pixelclock limit of the HDMI output, so X selects a 4kp60 format at 594
MHz, which obviously won't work.

The patch below adds a check for the upper bound of what this hardware can
do, and it checks if the requested tmds clock can be obtained.

It also allows for the +/- 0.5% pixel clock variation that the HDMI spec permits.

That code is based on commit 22d0be2a55 ("drm: arcpgu: Allow some clock
deviation in crtc->mode_valid() callback") from Jose Abreu for drm/arc.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Thanks-to: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/162854cb-c7bd-d9ce-9fa0-9a6cd89c621b@xs4all.nl
This commit is contained in:
Hans Verkuil 2017-12-15 16:21:50 +01:00 committed by Maxime Ripard
parent bd36d3bab2
commit caea4f3848
1 changed files with 19 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
View File

@ -208,8 +208,27 @@ static int sun4i_hdmi_get_modes(struct drm_connector *connector)
return ret; return ret;
} }
static int sun4i_hdmi_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
{
struct sun4i_hdmi *hdmi = drm_connector_to_sun4i_hdmi(connector);
long rate = mode->clock * 1000;
long diff = rate / 200; /* +-0.5% allowed by HDMI spec */
long rounded_rate;
/* 165 MHz is the typical max pixelclock frequency for HDMI <= 1.2 */
if (rate > 165000000)
return MODE_CLOCK_HIGH;
rounded_rate = clk_round_rate(hdmi->tmds_clk, rate);
if (max(rounded_rate, rate) - min(rounded_rate, rate) < diff &&
rounded_rate > 0)
return MODE_OK;
return MODE_NOCLOCK;
}
static const struct drm_connector_helper_funcs sun4i_hdmi_connector_helper_funcs = { static const struct drm_connector_helper_funcs sun4i_hdmi_connector_helper_funcs = {
.get_modes = sun4i_hdmi_get_modes, .get_modes = sun4i_hdmi_get_modes,
.mode_valid = sun4i_hdmi_mode_valid,
}; };
static enum drm_connector_status static enum drm_connector_status