diff mbox series

[v2,4/5] drm/sun4i: sun6i_mipi_dsi: fix horizontal timing calculation

Message ID 20200316133503.144650-5-icenowy@aosc.io (mailing list archive)
State New, archived
Headers show
Series Add support for PinePhone LCD panel | expand

Commit Message

Icenowy Zheng March 16, 2020, 1:35 p.m. UTC 
The max() function call in horizontal timing calculation shouldn't pad a
length already subtracted with overhead to overhead, instead it should
only prevent the set timing to underflow.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
---
No changes in v2.

 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Comments

Maxime Ripard March 19, 2020, 9:54 a.m. UTC | #1 
Hi,

On Mon, Mar 16, 2020 at 09:35:02PM +0800, Icenowy Zheng wrote:
> The max() function call in horizontal timing calculation shouldn't pad a
> length already subtracted with overhead to overhead, instead it should
> only prevent the set timing to underflow.

Some explanation on why it shouldn't do that would be appreciated.

Also, with the changes you have below, the comments above each max
call don't match anymore and should be updated.

Maxime
diff mbox series

Patch

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 059939789730..5f2313c40328 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -555,7 +555,7 @@  static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 		 */
 #define HSA_PACKET_OVERHEAD	10
 		hsa = max((unsigned int)HSA_PACKET_OVERHEAD,
-			  (mode->hsync_end - mode->hsync_start) * Bpp - HSA_PACKET_OVERHEAD);
+			  (mode->hsync_end - mode->hsync_start) * Bpp) - HSA_PACKET_OVERHEAD;
 
 		/*
 		 * The backporch is set using a blanking packet (4
@@ -564,7 +564,7 @@  static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 		 */
 #define HBP_PACKET_OVERHEAD	6
 		hbp = max((unsigned int)HBP_PACKET_OVERHEAD,
-			  (mode->htotal - mode->hsync_end) * Bpp - HBP_PACKET_OVERHEAD);
+			  (mode->htotal - mode->hsync_end) * Bpp) - HBP_PACKET_OVERHEAD;
 
 		/*
 		 * The frontporch is set using a sync event (4 bytes)
@@ -574,7 +574,7 @@  static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 		 */
 #define HFP_PACKET_OVERHEAD	16
 		hfp = max((unsigned int)HFP_PACKET_OVERHEAD,
-			  (mode->hsync_start - mode->hdisplay) * Bpp - HFP_PACKET_OVERHEAD);
+			  (mode->hsync_start - mode->hdisplay) * Bpp) - HFP_PACKET_OVERHEAD;
 
 		/*
 		 * The blanking is set using a sync event (4 bytes)
@@ -583,8 +583,8 @@  static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 		 */
 #define HBLK_PACKET_OVERHEAD	10
 		hblk = max((unsigned int)HBLK_PACKET_OVERHEAD,
-			   (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp -
-			   HBLK_PACKET_OVERHEAD);
+			   (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp) -
+			   HBLK_PACKET_OVERHEAD;
 
 		/*
 		 * And I'm not entirely sure what vblk is about. The driver in