[PATCH] drm/modes: tag unused variables to avoid warnings

[Benjamin Gaignard <benjamin.gaignard@st.com>]

Some variables are set but never used. To avoid warning when compiling
with W=1 and keep the algorithm like it is tag theses variables
with _maybe_unused macro.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
---
changes in this version:
- do not modify the code to remove the unused variables
  just prefix them with __maybe_unused macro.
  
 drivers/gpu/drm/drm_modes.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 88232698d7a0..70aed4e2990d 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -233,7 +233,7 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay,
 		/* 3) Nominal HSync width (% of line period) - default 8 */
 #define CVT_HSYNC_PERCENTAGE	8
 		unsigned int hblank_percentage;
-		int vsyncandback_porch, vback_porch, hblank;
+		int vsyncandback_porch, __maybe_unused vback_porch, hblank;
 
 		/* estimated the horizontal period */
 		tmp1 = HV_FACTOR * 1000000  -
@@ -386,9 +386,10 @@ drm_gtf_mode_complex(struct drm_device *dev, int hdisplay, int vdisplay,
 	int top_margin, bottom_margin;
 	int interlace;
 	unsigned int hfreq_est;
-	int vsync_plus_bp, vback_porch;
-	unsigned int vtotal_lines, vfieldrate_est, hperiod;
-	unsigned int vfield_rate, vframe_rate;
+	int vsync_plus_bp, __maybe_unused vback_porch;
+	unsigned int vtotal_lines, __maybe_unused vfieldrate_est;
+	unsigned int __maybe_unused hperiod;
+	unsigned int vfield_rate, __maybe_unused vframe_rate;
 	int left_margin, right_margin;
 	unsigned int total_active_pixels, ideal_duty_cycle;
 	unsigned int hblank, total_pixels, pixel_freq;
-- 
2.15.0