drm/i915/bxt: Adjusting the error in horizontal timings retrieval

In BXT DSI there is no regs programmed with few horizontal timings
in Pixels but txbyteclkhs.. So retrieval process adds some
ROUND_UP ERRORS in the process of PIXELS<==>txbyteclkhs.

Actually here for the given adjusted_mode, we are calculating the
value programmed to the port and then back to the horizontal timing
param in pixels. This is the expected value at the end of get_config,
including roundup errors. And if that is same as retrieved value
from port, then retrieved (HW state) adjusted_mode's horizontal
timings are corrected to match with SW state to nullify the errors.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461053894-5058-2-git-send-email-ramalingam.c@intel.com
(cherry picked from commit 042ab0c3c40be1efcaad6b526173b5536fc6c3bf)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 88 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
index efa306bb19c9..366ad6c67ce4 100644
--- a/drivers/gpu/drm/i915/intel_dsi.c
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -46,6 +46,14 @@ static const struct {
         },
 };
 
+/* return pixels in terms of txbyteclkhs */
+static u16 txbyteclkhs(u16 pixels, int bpp, int lane_count,
+                       u16 burst_mode_ratio)
+{
+        return DIV_ROUND_UP(DIV_ROUND_UP(pixels * bpp * burst_mode_ratio,
+                                         8 * 100), lane_count);
+}
+
 /* return pixels equvalent to txbyteclkhs */
 static u16 pixels_from_txbyteclkhs(u16 clk_hs, int bpp, int lane_count,
                         u16 burst_mode_ratio)
@@ -788,11 +796,19 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
         struct drm_i915_private *dev_priv = dev->dev_private;
         struct drm_display_mode *adjusted_mode =
                                         &pipe_config->base.adjusted_mode;
+        struct drm_display_mode *adjusted_mode_sw;
+        struct intel_crtc *intel_crtc;
         struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
         unsigned int lane_count = intel_dsi->lane_count;
         unsigned int bpp, fmt;
         enum port port;
         u16 hactive, hfp, hsync, hbp, vfp, vsync, vbp;
+        u16 hfp_sw, hsync_sw, hbp_sw;
+        u16 crtc_htotal_sw, crtc_hsync_start_sw, crtc_hsync_end_sw,
+                                crtc_hblank_start_sw, crtc_hblank_end_sw;
+
+        intel_crtc = to_intel_crtc(encoder->base.crtc);
+        adjusted_mode_sw = &intel_crtc->config->base.adjusted_mode;
 
         /*
          * Atleast one port is active as encoder->get_config called only if
@@ -856,8 +872,79 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
         adjusted_mode->crtc_vsync_end = vsync + adjusted_mode->crtc_vsync_start;
         adjusted_mode->crtc_vblank_start = adjusted_mode->crtc_vdisplay;
         adjusted_mode->crtc_vblank_end = adjusted_mode->crtc_vtotal;
-}
 
+        /*
+         * In BXT DSI there is no regs programmed with few horizontal timings
+         * in Pixels but txbyteclkhs.. So retrieval process adds some
+         * ROUND_UP ERRORS in the process of PIXELS<==>txbyteclkhs.
+         * Actually here for the given adjusted_mode, we are calculating the
+         * value programmed to the port and then back to the horizontal timing
+         * param in pixels. This is the expected value, including roundup errors
+         * And if that is same as retrieved value from port, then
+         * (HW state) adjusted_mode's horizontal timings are corrected to
+         * match with SW state to nullify the errors.
+         */
+        /* Calculating the value programmed to the Port register */
+        hfp_sw = adjusted_mode_sw->crtc_hsync_start -
+                                        adjusted_mode_sw->crtc_hdisplay;
+        hsync_sw = adjusted_mode_sw->crtc_hsync_end -
+                                        adjusted_mode_sw->crtc_hsync_start;
+        hbp_sw = adjusted_mode_sw->crtc_htotal -
+                                        adjusted_mode_sw->crtc_hsync_end;
+
+        if (intel_dsi->dual_link) {
+                hfp_sw /= 2;
+                hsync_sw /= 2;
+                hbp_sw /= 2;
+        }
+
+        hfp_sw = txbyteclkhs(hfp_sw, bpp, lane_count,
+                                                intel_dsi->burst_mode_ratio);
+        hsync_sw = txbyteclkhs(hsync_sw, bpp, lane_count,
+                            intel_dsi->burst_mode_ratio);
+        hbp_sw = txbyteclkhs(hbp_sw, bpp, lane_count,
+                                                intel_dsi->burst_mode_ratio);
+
+        /* Reverse calculating the adjusted mode parameters from port reg vals*/
+        hfp_sw = pixels_from_txbyteclkhs(hfp_sw, bpp, lane_count,
+                                                intel_dsi->burst_mode_ratio);
+        hsync_sw = pixels_from_txbyteclkhs(hsync_sw, bpp, lane_count,
+                                                intel_dsi->burst_mode_ratio);
+        hbp_sw = pixels_from_txbyteclkhs(hbp_sw, bpp, lane_count,
+                                                intel_dsi->burst_mode_ratio);
+
+        if (intel_dsi->dual_link) {
+                hfp_sw *= 2;
+                hsync_sw *= 2;
+                hbp_sw *= 2;
+        }
+
+        crtc_htotal_sw = adjusted_mode_sw->crtc_hdisplay + hfp_sw +
+                                                        hsync_sw + hbp_sw;
+        crtc_hsync_start_sw = hfp_sw + adjusted_mode_sw->crtc_hdisplay;
+        crtc_hsync_end_sw = hsync_sw + crtc_hsync_start_sw;
+        crtc_hblank_start_sw = adjusted_mode_sw->crtc_hdisplay;
+        crtc_hblank_end_sw = crtc_htotal_sw;
+
+        if (adjusted_mode->crtc_htotal == crtc_htotal_sw)
+                adjusted_mode->crtc_htotal = adjusted_mode_sw->crtc_htotal;
+
+        if (adjusted_mode->crtc_hsync_start == crtc_hsync_start_sw)
+                adjusted_mode->crtc_hsync_start =
+                                        adjusted_mode_sw->crtc_hsync_start;
+
+        if (adjusted_mode->crtc_hsync_end == crtc_hsync_end_sw)
+                adjusted_mode->crtc_hsync_end =
+                                        adjusted_mode_sw->crtc_hsync_end;
+
+        if (adjusted_mode->crtc_hblank_start == crtc_hblank_start_sw)
+                adjusted_mode->crtc_hblank_start =
+                                        adjusted_mode_sw->crtc_hblank_start;
+
+        if (adjusted_mode->crtc_hblank_end == crtc_hblank_end_sw)
+                adjusted_mode->crtc_hblank_end =
+                                        adjusted_mode_sw->crtc_hblank_end;
+}
 
 static void intel_dsi_get_config(struct intel_encoder *encoder,
                                  struct intel_crtc_state *pipe_config)
@@ -921,14 +1008,6 @@ static u16 txclkesc(u32 divider, unsigned int us)
         }
 }
 
-/* return pixels in terms of txbyteclkhs */
-static u16 txbyteclkhs(u16 pixels, int bpp, int lane_count,
-                       u16 burst_mode_ratio)
-{
-        return DIV_ROUND_UP(DIV_ROUND_UP(pixels * bpp * burst_mode_ratio,
-                                         8 * 100), lane_count);
-}
-
 static void set_dsi_timings(struct drm_encoder *encoder,
                             const struct drm_display_mode *adjusted_mode)
 {