drm/tegra: output: Make ->setup_clock() optional

In order to transition output drivers to using the struct tegra_output
as a helper rather than midlayer, make this callback optional. Instead
drivers should implement the equivalent as part of ->mode_fixup(). For
the conversion to atomic modesetting a new callback ->atomic_check()
should be implemented that updates the display controller's state with
the corresponding parent clock, rate and shift clock divider.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/dc.c

@@ -1066,11 +1066,19 @@ static int tegra_crtc_setup_clk(struct drm_crtc *crtc,
 	if (!output)
 		return -ENODEV;
 
+	/*
+	 * The ->setup_clock() callback is optional, but if encoders don't
+	 * implement it they most likely need to do the equivalent within the
+	 * ->mode_fixup() callback.
+	 */
+	if (!output->ops || !output->ops->setup_clock)
+		return 0;
+
 	/*
 	 * This assumes that the parent clock is pll_d_out0 or pll_d2_out
 	 * respectively, each of which divides the base pll_d by 2.
 	 */
-	err = tegra_output_setup_clock(output, dc->clk, pclk, &div);
+	err = output->ops->setup_clock(output, dc->clk, pclk, &div);
 	if (err < 0) {
 		dev_err(dc->dev, "failed to setup clock: %ld\n", err);
 		return err;

drivers/gpu/drm/tegra/drm.h

@@ -240,16 +240,6 @@ static inline int tegra_output_disable(struct tegra_output *output)
 	return output ? -ENOSYS : -EINVAL;
 }
 
-static inline int tegra_output_setup_clock(struct tegra_output *output,
-					   struct clk *clk, unsigned long pclk,
-					   unsigned int *div)
-{
-	if (output && output->ops && output->ops->setup_clock)
-		return output->ops->setup_clock(output, clk, pclk, div);
-
-	return output ? -ENOSYS : -EINVAL;
-}
-
 static inline int tegra_output_check_mode(struct tegra_output *output,
 					  struct drm_display_mode *mode,
 					  enum drm_mode_status *status)