drm/bridge: cdns-dsi: Use video mode and clean up cdns_dsi_mode2cfg()

The driver does all the calculations and programming with video timings
(hftp, hbp, etc.) instead of the modeline values (hsync_start, ...).
Thus it makes sense to use struct videomode instead of struct
drm_display_mode internally.

Switch to videomode and do some cleanups in cdns_dsi_mode2cfg() along
the way.

Tested-by: Parth Pancholi <parth.pancholi@toradex.com>
Reviewed-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
Tested-by: Jayesh Choudhary <j-choudhary@ti.com>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Link: https://lore.kernel.org/r/20250723-cdns-dsi-impro-v5-12-e61cc06074c2@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Author: tomba

drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c

@@ -9,6 +9,7 @@
 #include <drm/drm_drv.h>
 #include <drm/drm_probe_helper.h>
 #include <video/mipi_display.h>
+#include <video/videomode.h>
 
 #include <linux/clk.h>
 #include <linux/interrupt.h>
@@ -467,36 +468,35 @@ static unsigned int dpi_to_dsi_timing(unsigned int dpi_timing,
 }
 
 static int cdns_dsi_mode2cfg(struct cdns_dsi *dsi,
-			     const struct drm_display_mode *mode,
+			     const struct videomode *vm,
 			     struct cdns_dsi_cfg *dsi_cfg)
 {
 	struct cdns_dsi_output *output = &dsi->output;
-	unsigned int tmp;
-	bool sync_pulse = false;
+	u32 dpi_hsa, dpi_hbp, dpi_hfp, dpi_hact;
+	bool sync_pulse;
 	int bpp;
 
+	dpi_hsa = vm->hsync_len;
+	dpi_hbp = vm->hback_porch;
+	dpi_hfp = vm->hfront_porch;
+	dpi_hact = vm->hactive;
+
 	memset(dsi_cfg, 0, sizeof(*dsi_cfg));
 
-	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
-		sync_pulse = true;
+	sync_pulse = output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
 
 	bpp = mipi_dsi_pixel_format_to_bpp(output->dev->format);
 
-	tmp = mode->htotal -
-		(sync_pulse ? mode->hsync_end : mode->hsync_start);
+	dsi_cfg->hbp = dpi_to_dsi_timing(dpi_hbp + (sync_pulse ? 0 : dpi_hsa),
+					 bpp, DSI_HBP_FRAME_OVERHEAD);
 
-	dsi_cfg->hbp = dpi_to_dsi_timing(tmp, bpp, DSI_HBP_FRAME_OVERHEAD);
+	if (sync_pulse)
+		dsi_cfg->hsa =
+			dpi_to_dsi_timing(dpi_hsa, bpp, DSI_HSA_FRAME_OVERHEAD);
 
-	if (sync_pulse) {
-		tmp = mode->hsync_end - mode->hsync_start;
+	dsi_cfg->hact = dpi_to_dsi_timing(dpi_hact, bpp, 0);
 
-		dsi_cfg->hsa = dpi_to_dsi_timing(tmp, bpp,
-						 DSI_HSA_FRAME_OVERHEAD);
-	}
-
-	dsi_cfg->hact = dpi_to_dsi_timing(mode->hdisplay, bpp, 0);
-	dsi_cfg->hfp = dpi_to_dsi_timing(mode->hsync_start - mode->hdisplay,
-					 bpp, DSI_HFP_FRAME_OVERHEAD);
+	dsi_cfg->hfp = dpi_to_dsi_timing(dpi_hfp, bpp, DSI_HFP_FRAME_OVERHEAD);
 
 	dsi_cfg->htotal = dsi_cfg->hbp + DSI_HBP_FRAME_OVERHEAD;
 	if (output->dev->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
@@ -509,19 +509,19 @@ static int cdns_dsi_mode2cfg(struct cdns_dsi *dsi,
 }
 
 static int cdns_dsi_check_conf(struct cdns_dsi *dsi,
-			       const struct drm_display_mode *mode,
+			       const struct videomode *vm,
 			       struct cdns_dsi_cfg *dsi_cfg)
 {
 	struct cdns_dsi_output *output = &dsi->output;
 	struct phy_configure_opts_mipi_dphy *phy_cfg = &output->phy_opts.mipi_dphy;
 	unsigned int nlanes = output->dev->lanes;
 	int ret;
 
-	ret = cdns_dsi_mode2cfg(dsi, mode, dsi_cfg);
+	ret = cdns_dsi_mode2cfg(dsi, vm, dsi_cfg);
 	if (ret)
 		return ret;
 
-	ret = phy_mipi_dphy_get_default_config(mode->clock * 1000,
+	ret = phy_mipi_dphy_get_default_config(vm->pixelclock,
 					       mipi_dsi_pixel_format_to_bpp(output->dev->format),
 					       nlanes, phy_cfg);
 	if (ret)
@@ -916,12 +916,15 @@ static int cdns_dsi_bridge_atomic_check(struct drm_bridge *bridge,
 	struct cdns_dsi_bridge_state *dsi_state = to_cdns_dsi_bridge_state(bridge_state);
 	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
 	struct cdns_dsi_cfg *dsi_cfg = &dsi_state->dsi_cfg;
+	struct videomode vm;
 
 	/* cdns-dsi requires negative syncs */
 	adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
 	adjusted_mode->flags |= DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC;
 
-	return cdns_dsi_check_conf(dsi, adjusted_mode, dsi_cfg);
+	drm_display_mode_to_videomode(adjusted_mode, &vm);
+
+	return cdns_dsi_check_conf(dsi, &vm, dsi_cfg);
 }
 
 static struct drm_bridge_state *