drm/bridge: tc358767: Drop line_pixel_subtract

This line_pixel_subtract is no longer needed now that the bridge can
request and obtain specific pixel clock on input to the bridge, with
clock frequency that matches the Pixel PLL frequency.

The line_pixel_subtract is now always 0, so drop it entirely.

The line_pixel_subtract was not reliable as it never worked when the
Pixel PLL and input clock were off just so that the required amount
of pixels to subtract would not be whole integer.
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240625120334.145320-3-marex@denx.de

drivers/gpu/drm/bridge/tc358767.c

@@ -382,9 +382,6 @@ struct tc_data {
 
 	/* HPD pin number (0 or 1) or -ENODEV */
 	int			hpd_pin;
-
-	/* Number of pixels to subtract from a line due to pixel clock delta */
-	u32			line_pixel_subtract;
 };
 
 static inline struct tc_data *aux_to_tc(struct drm_dp_aux *a)
@@ -580,11 +577,6 @@ static int tc_pllupdate(struct tc_data *tc, unsigned int pllctrl)
 	return 0;
 }
 
-static u32 div64_round_up(u64 v, u32 d)
-{
-	return div_u64(v + d - 1, d);
-}
-
 static int tc_pxl_pll_calc(struct tc_data *tc, u32 refclk, u32 pixelclock,
 			   int *out_best_pixelclock, u32 *out_pxl_pllparam)
 {
@@ -666,11 +658,7 @@ static int tc_pxl_pll_calc(struct tc_data *tc, u32 refclk, u32 pixelclock,
 		return -EINVAL;
 	}
 
-	tc->line_pixel_subtract = tc->mode.htotal -
-		div64_round_up(tc->mode.htotal * (u64)best_pixelclock, pixelclock);
-
-	dev_dbg(tc->dev, "PLL: got %d, delta %d (subtract %d px)\n", best_pixelclock,
-		best_delta, tc->line_pixel_subtract);
+	dev_dbg(tc->dev, "PLL: got %d, delta %d\n", best_pixelclock, best_delta);
 	dev_dbg(tc->dev, "PLL: %d / %d / %d * %d / %d\n", refclk,
 		ext_div[best_pre], best_div, best_mul, ext_div[best_post]);
 
@@ -914,13 +902,6 @@ static int tc_set_common_video_mode(struct tc_data *tc,
 		upper_margin, lower_margin, vsync_len);
 	dev_dbg(tc->dev, "total: %dx%d\n", mode->htotal, mode->vtotal);
 
-	if (right_margin > tc->line_pixel_subtract) {
-		right_margin -= tc->line_pixel_subtract;
-	} else {
-		dev_err(tc->dev, "Bridge pixel clock too slow for mode\n");
-		right_margin = 0;
-	}
-
 	/*
 	 * LCD Ctl Frame Size
 	 * datasheet is not clear of vsdelay in case of DPI