video: tegra: updated comments, move front_porch work around

Updated several comments to make code easier to read and understand.
Also use the front_porch workaround in any case, for HDMI output
too.

2 files changed, 28 insertions, 11 deletions

diff --git a/drivers/video/tegra/dc/mode.c b/drivers/video/tegra/dc/mode.c
index 0a0e730ad174..be0d2bc5f035 100644
--- a/drivers/video/tegra/dc/mode.c
+++ b/drivers/video/tegra/dc/mode.c
@@ -388,19 +388,22 @@ int tegra_dc_var_to_dc_mode(struct tegra_dc *dc, struct fb_var_screeninfo *var,
 	mode->h_front_porch = var->right_margin;
 	mode->v_front_porch = var->lower_margin;
 	mode->stereo_mode = stereo_mode;
+
+	/*
+	 * HACK:
+	 * If v_front_porch is only 1, we would violate Constraint 5/6
+	 * in this case, increase front porch by 1
+	 */
+	if (mode->v_front_porch <= 1)
+		mode->v_front_porch = 2;
+
+
 	if (dc->out->type == TEGRA_DC_OUT_HDMI) {
 		/* HDMI controller requires h_ref=1, v_ref=1 */
 		mode->h_ref_to_sync = 1;
 		mode->v_ref_to_sync = 1;
 	} else {
-		/*
-		 * HACK:
-		 * If v_front_porch is only 1, we would violate Constraint 5/6
-		 * in this case, increase front porch by 1
-		 */
-		if (mode->v_front_porch <= 1)
-			mode->v_front_porch = 2;
-
+		/* Calculate ref_to_sync signals */
 		err = calc_ref_to_sync(mode);
 		if (err) {
 			dev_err(&dc->ndev->dev, "display timing ref_to_sync"
@@ -441,7 +444,10 @@ int tegra_dc_var_to_dc_mode(struct tegra_dc *dc, struct fb_var_screeninfo *var,
 }
 EXPORT_SYMBOL(tegra_dc_var_to_dc_mode);
 
-
+/*
+ * This method is only used by sysfs interface
+ * /sys/devices/tegradc.1/nvdps
+ */
 int tegra_dc_set_fb_mode(struct tegra_dc *dc,
 		const struct fb_videomode *fbmode, bool stereo_mode)
 {
diff --git a/drivers/video/tegra/fb.c b/drivers/video/tegra/fb.c
index 90d1363ecf9c..70b82bde9e43 100644
--- a/drivers/video/tegra/fb.c
+++ b/drivers/video/tegra/fb.c
@@ -125,7 +125,9 @@ static int tegra_fb_set_par(struct fb_info *info)
 
 	struct tegra_dc_mode mode;
 
-
+	/* This is usually altered to 16/32 by tegra_fb_check_var
+	 * above which is called before this function
+	 */
 	switch (var->bits_per_pixel) {
 	case 32:
 		tegra_fb->win->fmt = TEGRA_WIN_FMT_R8G8B8A8;
@@ -167,6 +169,7 @@ static int tegra_fb_set_par(struct fb_info *info)
 		return -EINVAL;
 	}
 
+	/* Reflect changes on HW */
 	if (dc->enabled)
 		tegra_dc_disable(dc);
 	tegra_dc_enable(dc);
@@ -678,6 +681,12 @@ struct tegra_fb_info *tegra_fb_register(struct nvhost_device *ndev,
 	if (option != NULL)
 	{
 		if (!strcmp(option, "off")) {
+			/* This off option works perfectly for framebuffer
+			 * device, however the tegra binary driver somehow
+			 * has troubles to handle a missing fb0 when there
+			 * (then, dc1 gets remapped to fb0, which seems
+			 * to be an issue for the binary driver)...
+			 */
 			ret = -ENODEV;
 			goto err_iounmap_fb;
 		}
@@ -687,7 +696,9 @@ struct tegra_fb_info *tegra_fb_register(struct nvhost_device *ndev,
 		}
 	}
 
-	/* activate current settings.. */
+	/* Activate current settings (tegra_fb_find_mode has call
+	 * tegra_fb_check_var already)
+	 */
 	if (fb_mem)
 		tegra_fb_set_par(info);