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Revert "drm/sun4i: Handle DRM_BUS_FLAG_PIXDATA_*EDGE"

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This reverts commit 2c17a4368a.

The offending commit triggers a run-time fault when accessing the panel
element of the sun4i_tcon structure when no such panel is attached.

It was apparently assumed in said commit that a panel is always used with
the TCON. Although it is often the case, this is not always true.
For instance a bridge might be used instead of a panel.

This issue was discovered using an A13-OLinuXino, that uses the TCON
in RGB mode for a simple DAC-based VGA bridge.

Cc: stable@vger.kernel.org
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180613081647.31183-1-paul.kocialkowski@bootlin.com
This commit is contained in:
Paul Kocialkowski 2018-06-13 10:16:47 +02:00 committed by Maxime Ripard
parent 9fcf2b3c1c
commit 58b3d02f06
No known key found for this signature in database
GPG Key ID: D2B4C094214DAF74
1 changed files with 0 additions and 25 deletions
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25
drivers/gpu/drm/sun4i/sun4i_tcon.c
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@ -17,7 +17,6 @@
#include <drm/drm_encoder.h>
#include <drm/drm_modes.h>
#include <drm/drm_of.h>
#include <drm/drm_panel.h>
#include <uapi/drm/drm_mode.h>
@ -350,9 +349,6 @@ static void sun4i_tcon0_mode_set_lvds(struct sun4i_tcon *tcon,
static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
const struct drm_display_mode *mode)
{
struct drm_panel *panel = tcon->panel;
struct drm_connector *connector = panel->connector;
struct drm_display_info display_info = connector->display_info;
unsigned int bp, hsync, vsync;
u8 clk_delay;
u32 val = 0;
@ -410,27 +406,6 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
if (mode->flags & DRM_MODE_FLAG_PVSYNC)
val |= SUN4I_TCON0_IO_POL_VSYNC_POSITIVE;
/*
* On A20 and similar SoCs, the only way to achieve Positive Edge
* (Rising Edge), is setting dclk clock phase to 2/3(240°).
* By default TCON works in Negative Edge(Falling Edge),
* this is why phase is set to 0 in that case.
* Unfortunately there's no way to logically invert dclk through
* IO_POL register.
* The only acceptable way to work, triple checked with scope,
* is using clock phase set to 0° for Negative Edge and set to 240°
* for Positive Edge.
* On A33 and similar SoCs there would be a 90° phase option,
* but it divides also dclk by 2.
* Following code is a way to avoid quirks all around TCON
* and DOTCLOCK drivers.
*/
if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE)
clk_set_phase(tcon->dclk, 240);
if (display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE)
clk_set_phase(tcon->dclk, 0);
regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG,
SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | SUN4I_TCON0_IO_POL_VSYNC_POSITIVE,
val);