[Intel-gfx] [RFC 04/14] drm/i915: Calculate bw timer for mipi DBI interface

[Gaurav K Singh]

This patch will calculate the bandwidth timer for MIPI DBI interface.
If the BW timer value is available from VBT, then value from VBT
will be used.

Signed-off-by: Gaurav K Singh <gaurav.k.singh at intel.com>
Signed-off-by: Yogesh Mohan Marimuthu <yogesh.mohan.marimuthu at intel.com>
---
 drivers/gpu/drm/i915/intel_dsi_panel_vbt.c |   24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
index 9deaec3..38de166 100644
--- a/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
+++ b/drivers/gpu/drm/i915/intel_dsi_panel_vbt.c
@@ -56,6 +56,11 @@ static inline struct vbt_panel *to_vbt_panel(struct drm_panel *panel)
 #define CLK_ZERO_CNT_MAX	0xFF
 #define TRAIL_CNT_MAX		0x1F
 
+#define LP_HDR_FOOT_SIZE	6
+#define BW_LP_NUM_OF_PKT	16
+#define BW_LP_LOAD_SIZE		252
+#define EXTRA_ONE_BYTE		1
+
 #define NS_KHZ_RATIO 1000000
 
 #define GPI0_NC_0_HV_DDI0_HPD           0x4130
@@ -430,7 +435,6 @@ struct drm_panel *vbt_panel_init(struct intel_dsi *intel_dsi, u16 panel_id)
 	intel_dsi->turn_arnd_val = mipi_config->turn_around_timeout;
 	intel_dsi->rst_timer_val = mipi_config->device_reset_timer;
 	intel_dsi->init_count = mipi_config->master_init_timer;
-	intel_dsi->bw_timer = mipi_config->dbi_bw_timer;
 	intel_dsi->video_frmt_cfg_bits =
 		mipi_config->bta_enabled ? DISABLE_VIDEO_BTA : 0;
 
@@ -588,6 +592,24 @@ struct drm_panel *vbt_panel_init(struct intel_dsi *intel_dsi, u16 panel_id)
 	intel_dsi->dphy_reg = exit_zero_cnt << 24 | trail_cnt << 16 |
 						clk_zero_cnt << 8 | prepare_cnt;
 
+	if (mipi_config->dbi_bw_timer) {
+		intel_dsi->bw_timer = mipi_config->dbi_bw_timer;
+	} else {
+		/*
+		 * bw timer should be more than 16 longs packets containing
+		 * 252 bytes + 2 blanking packets.
+		 * bw timer = 16 long packets * (252 bytes payload for each
+		 *            long packet + 6 bytes for long packet header and
+		 *            footer) + 12 bytes for 2 blanking packets + 1
+		 *            byte for having more of the above.
+		 */
+		intel_dsi->bw_timer = DIV_ROUND_UP(BW_LP_NUM_OF_PKT *
+					(BW_LP_LOAD_SIZE + LP_HDR_FOOT_SIZE),
+					intel_dsi->lane_count);
+
+		intel_dsi->bw_timer += (extra_byte_count + EXTRA_ONE_BYTE);
+	}
+
 	/*
 	 * LP to HS switch count = 4TLPX + PREP_COUNT * 2 + EXIT_ZERO_COUNT * 2
 	 *					+ 10UI + Extra Byte Count
-- 
1.7.9.5