drm/modes: Add a function to generate analog display modes

Multiple drivers (meson, vc4, sun4i) define analog TV 525-lines and
625-lines modes in their drivers.

Since those modes are fairly standard, and that we'll need to use them
in more places in the future, it makes sense to move their definition
into the core framework.

However, analog display usually have fairly loose timings requirements,
the only discrete parameters being the total number of lines and pixel
clock frequency. Thus, we created a function that will create a display
mode from the standard, the pixel frequency and the active area.
Tested-by: Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>
Acked-in-principle-or-something-like-that-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://lore.kernel.org/r/20220728-rpi-analog-tv-properties-v10-6-256dad125326@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/tests/Makefile

@@ -10,5 +10,6 @@ obj-$(CONFIG_DRM_KUNIT_TEST) += \
 	drm_framebuffer_test.o \
 	drm_kunit_helpers.o \
 	drm_mm_test.o \
+	drm_modes_test.o \
 	drm_plane_helper_test.o \
 	drm_rect_test.o

drivers/gpu/drm/tests/drm_modes_test.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Kunit test for drm_modes functions
+ */
+
+#include <drm/drm_drv.h>
+#include <drm/drm_modes.h>
+
+#include <kunit/test.h>
+
+#include <linux/units.h>
+
+#include "drm_kunit_helpers.h"
+
+struct drm_test_modes_priv {
+	struct drm_device *drm;
+};
+
+static int drm_test_modes_init(struct kunit *test)
+{
+	struct drm_test_modes_priv *priv;
+
+	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	priv->drm = drm_kunit_device_init(test, DRIVER_MODESET, "drm-modes-test");
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->drm);
+
+	test->priv = priv;
+
+	return 0;
+}
+
+static void drm_test_modes_analog_tv_ntsc_480i(struct kunit *test)
+{
+	struct drm_test_modes_priv *priv = test->priv;
+	struct drm_display_mode *mode;
+
+	mode = drm_analog_tv_mode(priv->drm,
+				  DRM_MODE_TV_MODE_NTSC,
+				  13500 * HZ_PER_KHZ, 720, 480,
+				  true);
+	KUNIT_ASSERT_NOT_NULL(test, mode);
+
+	KUNIT_EXPECT_EQ(test, drm_mode_vrefresh(mode), 60);
+	KUNIT_EXPECT_EQ(test, mode->hdisplay, 720);
+
+	/* BT.601 defines hsync_start at 736 for 480i */
+	KUNIT_EXPECT_EQ(test, mode->hsync_start, 736);
+
+	/*
+	 * The NTSC standard expects a line to take 63.556us. With a
+	 * pixel clock of 13.5 MHz, a pixel takes around 74ns, so we
+	 * need to have 63556ns / 74ns = 858.
+	 *
+	 * This is also mandated by BT.601.
+	 */
+	KUNIT_EXPECT_EQ(test, mode->htotal, 858);
+
+	KUNIT_EXPECT_EQ(test, mode->vdisplay, 480);
+	KUNIT_EXPECT_EQ(test, mode->vtotal, 525);
+}
+
+static void drm_test_modes_analog_tv_ntsc_480i_inlined(struct kunit *test)
+{
+	struct drm_test_modes_priv *priv = test->priv;
+	struct drm_display_mode *expected, *mode;
+
+	expected = drm_analog_tv_mode(priv->drm,
+				      DRM_MODE_TV_MODE_NTSC,
+				      13500 * HZ_PER_KHZ, 720, 480,
+				      true);
+	KUNIT_ASSERT_NOT_NULL(test, expected);
+
+	mode = drm_mode_analog_ntsc_480i(priv->drm);
+	KUNIT_ASSERT_NOT_NULL(test, mode);
+
+	KUNIT_EXPECT_TRUE(test, drm_mode_equal(expected, mode));
+}
+
+static void drm_test_modes_analog_tv_pal_576i(struct kunit *test)
+{
+	struct drm_test_modes_priv *priv = test->priv;
+	struct drm_display_mode *mode;
+
+	mode = drm_analog_tv_mode(priv->drm,
+				  DRM_MODE_TV_MODE_PAL,
+				  13500 * HZ_PER_KHZ, 720, 576,
+				  true);
+	KUNIT_ASSERT_NOT_NULL(test, mode);
+
+	KUNIT_EXPECT_EQ(test, drm_mode_vrefresh(mode), 50);
+	KUNIT_EXPECT_EQ(test, mode->hdisplay, 720);
+
+	/* BT.601 defines hsync_start at 732 for 576i */
+	KUNIT_EXPECT_EQ(test, mode->hsync_start, 732);
+
+	/*
+	 * The PAL standard expects a line to take 64us. With a pixel
+	 * clock of 13.5 MHz, a pixel takes around 74ns, so we need to
+	 * have 64000ns / 74ns = 864.
+	 *
+	 * This is also mandated by BT.601.
+	 */
+	KUNIT_EXPECT_EQ(test, mode->htotal, 864);
+
+	KUNIT_EXPECT_EQ(test, mode->vdisplay, 576);
+	KUNIT_EXPECT_EQ(test, mode->vtotal, 625);
+}
+
+static void drm_test_modes_analog_tv_pal_576i_inlined(struct kunit *test)
+{
+	struct drm_test_modes_priv *priv = test->priv;
+	struct drm_display_mode *expected, *mode;
+
+	expected = drm_analog_tv_mode(priv->drm,
+				      DRM_MODE_TV_MODE_PAL,
+				      13500 * HZ_PER_KHZ, 720, 576,
+				      true);
+	KUNIT_ASSERT_NOT_NULL(test, expected);
+
+	mode = drm_mode_analog_pal_576i(priv->drm);
+	KUNIT_ASSERT_NOT_NULL(test, mode);
+
+	KUNIT_EXPECT_TRUE(test, drm_mode_equal(expected, mode));
+}
+
+static struct kunit_case drm_modes_analog_tv_tests[] = {
+	KUNIT_CASE(drm_test_modes_analog_tv_ntsc_480i),
+	KUNIT_CASE(drm_test_modes_analog_tv_ntsc_480i_inlined),
+	KUNIT_CASE(drm_test_modes_analog_tv_pal_576i),
+	KUNIT_CASE(drm_test_modes_analog_tv_pal_576i_inlined),
+	{ }
+};
+
+static struct kunit_suite drm_modes_analog_tv_test_suite = {
+	.name = "drm_modes_analog_tv",
+	.init = drm_test_modes_init,
+	.test_cases = drm_modes_analog_tv_tests,
+};
+
+kunit_test_suite(drm_modes_analog_tv_test_suite);
+
+MODULE_AUTHOR("Maxime Ripard <maxime@cerno.tech>");
+MODULE_LICENSE("GPL");

include/drm/drm_modes.h

@@ -468,6 +468,23 @@ bool drm_mode_is_420_also(const struct drm_display_info *display,
 bool drm_mode_is_420(const struct drm_display_info *display,
 		     const struct drm_display_mode *mode);
 
+struct drm_display_mode *drm_analog_tv_mode(struct drm_device *dev,
+					    enum drm_connector_tv_mode mode,
+					    unsigned long pixel_clock_hz,
+					    unsigned int hdisplay,
+					    unsigned int vdisplay,
+					    bool interlace);
+
+static inline struct drm_display_mode *drm_mode_analog_ntsc_480i(struct drm_device *dev)
+{
+	return drm_analog_tv_mode(dev, DRM_MODE_TV_MODE_NTSC, 13500000, 720, 480, true);
+}
+
+static inline struct drm_display_mode *drm_mode_analog_pal_576i(struct drm_device *dev)
+{
+	return drm_analog_tv_mode(dev, DRM_MODE_TV_MODE_PAL, 13500000, 720, 576, true);
+}
+
 struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,
 				      int hdisplay, int vdisplay, int vrefresh,
 				      bool reduced, bool interlaced,