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Subject[PATCH v5 2/7] drm/panel: simple: Add ability to override typical timing
Date
From: Sean Paul <seanpaul@chromium.org>

This patch adds the ability to override the typical display timing for a
given panel. This is useful for devices which have timing constraints
that do not apply across the entire display driver (eg: to avoid
crosstalk between panel and digitizer on certain laptops). The rules are
as follows:

- panel must not specify fixed mode (since the override mode will
either be the same as the fixed mode, or we'll be unable to
check the bounds of the overried)
- panel must specify at least one display_timing range which will be
used to ensure the override mode fits within its bounds

Changes in v2:
- Parse the full display-timings node (using the native-mode) (Rob)
Changes in v3:
- No longer parse display-timings subnode, use panel-timing (Rob)
Changes in v4:
- Don't add mode from timing if override was specified (Thierry)
- Add warning if timing and fixed mode was specified (Thierry)
- Don't add fixed mode if timing was specified (Thierry)
- Refactor/rename a bit to avoid extra indentation from "if" tests
- i should be unsigned (Thierry)
- Add annoying WARN_ONs for some cases (Thierry)
- Simplify 'No display_timing found' handling (Thierry)
- Rename to panel_simple_parse_override_mode() (Thierry)
Changes in v5:
- Added Heiko's Tested-by

Cc: Doug Anderson <dianders@chromium.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: Jeffy Chen <jeffy.chen@rock-chips.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Stéphane Marchesin <marcheu@chromium.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: devicetree@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
---

drivers/gpu/drm/panel/panel-simple.c | 109 +++++++++++++++++++++++++--
1 file changed, 104 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 9e8218f6a3f2..ad4f4aac2d44 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -34,6 +34,7 @@
#include <drm/drm_panel.h>

#include <video/display_timing.h>
+#include <video/of_display_timing.h>
#include <video/videomode.h>

struct panel_desc {
@@ -91,6 +92,8 @@ struct panel_simple {
struct i2c_adapter *ddc;

struct gpio_desc *enable_gpio;
+
+ struct drm_display_mode override_mode;
};

static inline struct panel_simple *to_panel_simple(struct drm_panel *panel)
@@ -98,16 +101,13 @@ static inline struct panel_simple *to_panel_simple(struct drm_panel *panel)
return container_of(panel, struct panel_simple, base);
}

-static int panel_simple_get_fixed_modes(struct panel_simple *panel)
+static unsigned int panel_simple_get_timings_modes(struct panel_simple *panel)
{
struct drm_connector *connector = panel->base.connector;
struct drm_device *drm = panel->base.drm;
struct drm_display_mode *mode;
unsigned int i, num = 0;

- if (!panel->desc)
- return 0;
-
for (i = 0; i < panel->desc->num_timings; i++) {
const struct display_timing *dt = &panel->desc->timings[i];
struct videomode vm;
@@ -131,6 +131,16 @@ static int panel_simple_get_fixed_modes(struct panel_simple *panel)
num++;
}

+ return num;
+}
+
+static unsigned int panel_simple_get_fixed_modes(struct panel_simple *panel)
+{
+ struct drm_connector *connector = panel->base.connector;
+ struct drm_device *drm = panel->base.drm;
+ struct drm_display_mode *mode;
+ unsigned int i, num = 0;
+
for (i = 0; i < panel->desc->num_modes; i++) {
const struct drm_display_mode *m = &panel->desc->modes[i];

@@ -152,6 +162,44 @@ static int panel_simple_get_fixed_modes(struct panel_simple *panel)
num++;
}

+ return num;
+}
+
+static int panel_simple_get_non_edid_modes(struct panel_simple *panel)
+{
+ struct drm_connector *connector = panel->base.connector;
+ struct drm_device *drm = panel->base.drm;
+ struct drm_display_mode *mode;
+ bool has_override = panel->override_mode.type;
+ unsigned int num = 0;
+
+ if (!panel->desc)
+ return 0;
+
+ if (has_override) {
+ mode = drm_mode_duplicate(drm, &panel->override_mode);
+ if (mode) {
+ drm_mode_probed_add(connector, mode);
+ num = 1;
+ } else {
+ dev_err(drm->dev, "failed to add override mode\n");
+ }
+ }
+
+ /* Only add timings if override was not there or failed to validate */
+ if (num == 0 && panel->desc->num_timings)
+ num = panel_simple_get_timings_modes(panel);
+
+ /*
+ * Only add fixed modes if timings/override added no mode.
+ *
+ * We should only ever have either the display timings specified
+ * or a fixed mode. Anything else is rather bogus.
+ */
+ WARN_ON(panel->desc->num_timings && panel->desc->num_modes);
+ if (num == 0)
+ num = panel_simple_get_fixed_modes(panel);
+
connector->display_info.bpc = panel->desc->bpc;
connector->display_info.width_mm = panel->desc->size.width;
connector->display_info.height_mm = panel->desc->size.height;
@@ -268,7 +316,7 @@ static int panel_simple_get_modes(struct drm_panel *panel)
}

/* add hard-coded panel modes */
- num += panel_simple_get_fixed_modes(p);
+ num += panel_simple_get_non_edid_modes(p);

return num;
}
@@ -299,10 +347,58 @@ static const struct drm_panel_funcs panel_simple_funcs = {
.get_timings = panel_simple_get_timings,
};

+#define PANEL_SIMPLE_BOUNDS_CHECK(to_check, bounds, field) \
+ (to_check->field.typ >= bounds->field.min && \
+ to_check->field.typ <= bounds->field.max)
+static void panel_simple_parse_override_mode(struct device *dev,
+ struct panel_simple *panel,
+ const struct display_timing *ot)
+{
+ const struct panel_desc *desc = panel->desc;
+ struct videomode vm;
+ unsigned int i;
+
+ if (WARN_ON(desc->num_modes)) {
+ dev_err(dev, "Reject override mode: panel has a fixed mode\n");
+ return;
+ }
+ if (WARN_ON(!desc->num_timings)) {
+ dev_err(dev, "Reject override mode: no timings specified\n");
+ return;
+ }
+
+ for (i = 0; i < panel->desc->num_timings; i++) {
+ const struct display_timing *dt = &panel->desc->timings[i];
+
+ if (!PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hactive) ||
+ !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hfront_porch) ||
+ !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hback_porch) ||
+ !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hsync_len) ||
+ !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vactive) ||
+ !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vfront_porch) ||
+ !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vback_porch) ||
+ !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vsync_len))
+ continue;
+
+ if (ot->flags != dt->flags)
+ continue;
+
+ videomode_from_timing(ot, &vm);
+ drm_display_mode_from_videomode(&vm, &panel->override_mode);
+ panel->override_mode.type |= DRM_MODE_TYPE_DRIVER |
+ DRM_MODE_TYPE_PREFERRED;
+ break;
+ }
+
+ if (WARN_ON(!panel->override_mode.type))
+ dev_err(dev, "Reject override mode: No display_timing found\n");
+}
+
static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
{
struct device_node *backlight, *ddc;
struct panel_simple *panel;
+ struct display_timing dt;
int err;

panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
@@ -348,6 +444,9 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
}
}

+ if (!of_get_display_timing(dev->of_node, "panel-timing", &dt))
+ panel_simple_parse_override_mode(dev, panel, &dt);
+
drm_panel_init(&panel->base);
panel->base.dev = dev;
panel->base.funcs = &panel_simple_funcs;
--
2.21.0.392.gf8f6787159e-goog
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