imx-drm: core: handling of DI clock flags to ipu_crtc_mode_set()

We do not need to track the state of the IPU DI's clock flags by having
each display bridge calling back into imx-drm-core, and then back out
into ipuv3-crtc.c.

ipuv3-crtc can instead just scan the list of encoders to retrieve their
type, and build up a picture of which types of encoders are attached.
We can then use this information to configure the IPU DI clocking mode
without any uncertainty - if we have multiple bridges connected to the
same DI, if one of them requires a synchronous DI clock, that's what we
must use.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/drm/imx/imx-drm-core.c

@@ -116,8 +116,7 @@ int imx_drm_panel_format_pins(struct drm_encoder *encoder,
 	helper = &imx_crtc->imx_drm_helper_funcs;
 	if (helper->set_interface_pix_fmt)
 		return helper->set_interface_pix_fmt(encoder->crtc,
-				encoder->encoder_type, interface_pix_fmt,
-				hsync_pin, vsync_pin);
+				interface_pix_fmt, hsync_pin, vsync_pin);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(imx_drm_panel_format_pins);

drivers/gpu/drm/imx/imx-drm.h

@@ -17,7 +17,7 @@ int imx_drm_crtc_id(struct imx_drm_crtc *crtc);
 struct imx_drm_crtc_helper_funcs {
 	int (*enable_vblank)(struct drm_crtc *crtc);
 	void (*disable_vblank)(struct drm_crtc *crtc);
-	int (*set_interface_pix_fmt)(struct drm_crtc *crtc, u32 encoder_type,
+	int (*set_interface_pix_fmt)(struct drm_crtc *crtc,
 			u32 pix_fmt, int hsync_pin, int vsync_pin);
 	const struct drm_crtc_helper_funcs *crtc_helper_funcs;
 	const struct drm_crtc_funcs *crtc_funcs;

drivers/gpu/drm/imx/ipuv3-crtc.c

@@ -46,7 +46,6 @@ struct ipu_crtc {
 	struct drm_framebuffer	*newfb;
 	int			irq;
 	u32			interface_pix_fmt;
-	unsigned long		di_clkflags;
 	int			di_hsync_pin;
 	int			di_vsync_pin;
 };
@@ -141,22 +140,42 @@ static int ipu_crtc_mode_set(struct drm_crtc *crtc,
 			       int x, int y,
 			       struct drm_framebuffer *old_fb)
 {
+	struct drm_device *dev = crtc->dev;
+	struct drm_encoder *encoder;
 	struct ipu_crtc *ipu_crtc = to_ipu_crtc(crtc);
-	int ret;
 	struct ipu_di_signal_cfg sig_cfg = {};
+	unsigned long encoder_types = 0;
 	u32 out_pixel_fmt;
+	int ret;
 
 	dev_dbg(ipu_crtc->dev, "%s: mode->hdisplay: %d\n", __func__,
 			mode->hdisplay);
 	dev_dbg(ipu_crtc->dev, "%s: mode->vdisplay: %d\n", __func__,
 			mode->vdisplay);
 
+	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head)
+		if (encoder->crtc == crtc)
+			encoder_types |= BIT(encoder->encoder_type);
+
+	dev_dbg(ipu_crtc->dev, "%s: attached to encoder types 0x%lx\n",
+		__func__, encoder_types);
+
+	/*
+	 * If we have DAC, TVDAC or LDB, then we need the IPU DI clock
+	 * to be the same as the LDB DI clock.
+	 */
+	if (encoder_types & (BIT(DRM_MODE_ENCODER_DAC) |
+			     BIT(DRM_MODE_ENCODER_TVDAC) |
+			     BIT(DRM_MODE_ENCODER_LVDS)))
+		sig_cfg.clkflags = IPU_DI_CLKMODE_SYNC | IPU_DI_CLKMODE_EXT;
+	else
+		sig_cfg.clkflags = 0;
+
 	out_pixel_fmt = ipu_crtc->interface_pix_fmt;
 
 	sig_cfg.enable_pol = 1;
 	sig_cfg.clk_pol = 0;
 	sig_cfg.pixel_fmt = out_pixel_fmt;
-	sig_cfg.clkflags = ipu_crtc->di_clkflags;
 	sig_cfg.v_to_h_sync = 0;
 	sig_cfg.hsync_pin = ipu_crtc->di_hsync_pin;
 	sig_cfg.vsync_pin = ipu_crtc->di_vsync_pin;
@@ -271,7 +290,7 @@ static void ipu_disable_vblank(struct drm_crtc *crtc)
 	ipu_crtc->newfb = NULL;
 }
 
-static int ipu_set_interface_pix_fmt(struct drm_crtc *crtc, u32 encoder_type,
+static int ipu_set_interface_pix_fmt(struct drm_crtc *crtc,
 		u32 pixfmt, int hsync_pin, int vsync_pin)
 {
 	struct ipu_crtc *ipu_crtc = to_ipu_crtc(crtc);
@@ -280,19 +299,6 @@ static int ipu_set_interface_pix_fmt(struct drm_crtc *crtc, u32 encoder_type,
 	ipu_crtc->di_hsync_pin = hsync_pin;
 	ipu_crtc->di_vsync_pin = vsync_pin;
 
-	switch (encoder_type) {
-	case DRM_MODE_ENCODER_DAC:
-	case DRM_MODE_ENCODER_TVDAC:
-	case DRM_MODE_ENCODER_LVDS:
-		ipu_crtc->di_clkflags = IPU_DI_CLKMODE_SYNC |
-			IPU_DI_CLKMODE_EXT;
-		break;
-	case DRM_MODE_ENCODER_TMDS:
-	case DRM_MODE_ENCODER_NONE:
-		ipu_crtc->di_clkflags = 0;
-		break;
-	}
-
 	return 0;
 }