Re: [PATCH v3 1/3] drm/msm/dp: revise timing engine programming to support widebus feature

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On 2/4/2022 2:05 PM, Dmitry Baryshkov wrote:
On 04/02/2022 21:36, Kuogee Hsieh wrote:
Widebus feature will transmit two pixel data per pixel clock to interface.
Timing engine provides driving force for this purpose. This patch base
on HPG (Hardware Programming Guide) to revise timing engine register
setting to accommodate both widebus and non widebus application. Also
horizontal width parameters need to be reduced by half since two pixel
data are clocked out per pixel clock when widebus feature enabled.
In addition, revised timing engine function is an generic function and
intend to be shared by all platforms to reduce maintenance efforts.

Changes in v2:
-- remove compression related code from timing
-- remove op_info from  struct msm_drm_private
-- remove unnecessary wide_bus_en variables
-- pass wide_bus_en into timing configuration by struct msm_dp

Changes in v3:
-- split patch into 3 patches

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c        | 10 +++
  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h        |  2 +
  .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c   | 14 +++
  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c        | 99 ++++++++++++++--------
  drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h        |  2 +
  5 files changed, 93 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index 0d315b4..0c22839 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -208,6 +208,8 @@ struct dpu_encoder_virt {
        u32 idle_timeout;
  +    bool wide_bus_en;
+
      struct msm_dp *dp;
  };
  @@ -217,6 +219,14 @@ static u32 dither_matrix[DITHER_MATRIX_SZ] = {
      15, 7, 13, 5, 3, 11, 1, 9, 12, 4, 14, 6, 0, 8, 2, 10
  };
  +
+bool dpu_encoder_is_widebus_enabled(struct drm_encoder *drm_enc)
+{
+    struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
+
+    return dpu_enc->wide_bus_en;
+}
+
  static void _dpu_encoder_setup_dither(struct dpu_hw_pingpong *hw_pp, unsigned bpc)
  {
      struct dpu_hw_dither_cfg dither_cfg = { 0 };
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
index 99a5d73..893d74d 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
@@ -168,4 +168,6 @@ int dpu_encoder_get_linecount(struct drm_encoder *drm_enc);
   */
  int dpu_encoder_get_frame_count(struct drm_encoder *drm_enc);
  +bool dpu_encoder_is_widebus_enabled(struct drm_encoder *drm_enc);
+
  #endif /* __DPU_ENCODER_H__ */

This chunk does not apply against the msm-next. The conflict is trivial, but it would be nice to know that the code was tested against the current tip.
My fault, I forget to cherry-pick to msm-next this time before upload for review

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
index 185379b..3d6c914 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
@@ -110,6 +110,20 @@ static void drm_mode_to_intf_timing_params(
          timing->v_back_porch += timing->v_front_porch;
          timing->v_front_porch = 0;
      }
+
+    timing->wide_bus_en = dpu_encoder_is_widebus_enabled(phys_enc->parent);
+
+    /*
+     * for DP, divide the horizonal parameters by 2 when
+     * widebus is enabled
+     */
+    if (timing->wide_bus_en) {
+        timing->width = timing->width >> 1;
+        timing->xres = timing->xres >> 1;
+        timing->h_back_porch = timing->h_back_porch >> 1;
+        timing->h_front_porch = timing->h_front_porch >> 1;
+        timing->hsync_pulse_width = timing->hsync_pulse_width >> 1;
+    }
  }
    static u32 get_horizontal_total(const struct intf_timing_params *timing) diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
index 116e2b5..35d4aaa 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
@@ -33,6 +33,7 @@
  #define INTF_TP_COLOR1                  0x05C
  #define INTF_CONFIG2                    0x060
  #define INTF_DISPLAY_DATA_HCTL          0x064
+#define INTF_ACTIVE_DATA_HCTL           0x068
  #define INTF_FRAME_LINE_COUNT_EN        0x0A8
  #define INTF_FRAME_COUNT                0x0AC
  #define   INTF_LINE_COUNT               0x0B0
@@ -90,68 +91,95 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
      u32 hsync_period, vsync_period;
      u32 display_v_start, display_v_end;
      u32 hsync_start_x, hsync_end_x;
+    u32 hsync_data_start_x, hsync_data_end_x;
      u32 active_h_start, active_h_end;
      u32 active_v_start, active_v_end;
      u32 active_hctl, display_hctl, hsync_ctl;
      u32 polarity_ctl, den_polarity, hsync_polarity, vsync_polarity;
      u32 panel_format;
-    u32 intf_cfg, intf_cfg2 = 0, display_data_hctl = 0;
+    u32 intf_cfg, intf_cfg2 = 0;
+    u32 display_data_hctl = 0, active_data_hctl = 0;
+    u32 data_width;
+    bool dp_intf = false;
        /* read interface_cfg */
      intf_cfg = DPU_REG_READ(c, INTF_CONFIG);
+
+    if (ctx->cap->type == INTF_EDP || ctx->cap->type == INTF_DP)
+        dp_intf = true;
+
      hsync_period = p->hsync_pulse_width + p->h_back_porch + p->width +
      p->h_front_porch;
      vsync_period = p->vsync_pulse_width + p->v_back_porch + p->height +
      p->v_front_porch;
        display_v_start = ((p->vsync_pulse_width + p->v_back_porch) *
-    hsync_period) + p->hsync_skew;
+            hsync_period) + p->hsync_skew;
      display_v_end = ((vsync_period - p->v_front_porch) * hsync_period) +
-    p->hsync_skew - 1;
+            p->hsync_skew - 1;
+
+    hsync_ctl = (hsync_period << 16) | p->hsync_pulse_width;
        hsync_start_x = p->h_back_porch + p->hsync_pulse_width;
      hsync_end_x = hsync_period - p->h_front_porch - 1;
  -    if (p->width != p->xres) {
-        active_h_start = hsync_start_x;
-        active_h_end = active_h_start + p->xres - 1;
-    } else {
-        active_h_start = 0;
-        active_h_end = 0;
-    }
+    /*
+     * DATA_HCTL_EN controls data timing which can be different from
+     * video timing. It is recommended to enable it for all cases, except
+     * if compression is enabled in 1 pixel per clock mode
+     */
+    if (p->wide_bus_en)
+        intf_cfg2 |= BIT(4);
  -    if (p->height != p->yres) {
-        active_v_start = display_v_start;
-        active_v_end = active_v_start + (p->yres * hsync_period) - 1;
-    } else {
-        active_v_start = 0;
-        active_v_end = 0;
-    }
+    if (p->wide_bus_en)
+        intf_cfg2 |= BIT(0);
  -    if (active_h_end) {
-        active_hctl = (active_h_end << 16) | active_h_start;
-        intf_cfg |= BIT(29);    /* ACTIVE_H_ENABLE */
-    } else {
-        active_hctl = 0;
-    }
+    /*
+     * If widebus is disabled:
+     * For uncompressed stream, the data is valid for the entire active
+     * window period.
+     * For compressed stream, data is valid for a shorter time period
+     * inside the active window depending on the compression ratio.
+     *
+     * If widebus is enabled:
+     * For uncompressed stream, data is valid for only half the active
+     * window, since the data rate is doubled in this mode.
+     * p->width holds the adjusted width for DP but unadjusted width for DSI +     * For compressed stream, data validity window needs to be adjusted for
+     * compression ratio and then further halved.
+     */
+    data_width = p->width;

This assignment is rewritten in the next few lines! Please drop it, it's unused.

+
+    if (!dp_intf && p->wide_bus_en)

This condition does not make sense. wide_bus_en can only be enabled for dp_intf, can it not? So the condition is always false.

+        data_width = p->width >> 1;
+    else
+        data_width = p->width;
  -    if (active_v_end)
-        intf_cfg |= BIT(30); /* ACTIVE_V_ENABLE */
+    hsync_data_start_x = hsync_start_x;
+    hsync_data_end_x =  hsync_start_x + data_width - 1;
  -    hsync_ctl = (hsync_period << 16) | p->hsync_pulse_width;
      display_hctl = (hsync_end_x << 16) | hsync_start_x;
+    display_data_hctl = (hsync_data_end_x << 16) | hsync_data_start_x;
  -    if (ctx->cap->type == INTF_EDP || ctx->cap->type == INTF_DP) {
-        active_h_start = hsync_start_x;
-        active_h_end = active_h_start + p->xres - 1;
-        active_v_start = display_v_start;
-        active_v_end = active_v_start + (p->yres * hsync_period) - 1;
-
+    if (dp_intf) {
+        // DP timing adjustment

This is the only place with the C99 comment. Please use the surrounding syntax.

          display_v_start += p->hsync_pulse_width + p->h_back_porch;
+        display_v_end   -= p->h_front_porch;
+    }
+
+    active_h_start = hsync_start_x;
+    active_h_end = active_h_start + p->xres - 1;
+
+    active_v_start = display_v_start;
+    active_v_end = active_v_start + (p->yres * hsync_period) - 1;

These assignments were only applied for the DP/eDP case. Could you please elaborate the change? Why are you enabling them for the DSI and HDMI outputs?

All interface have those registers for active_v_xx and acrive_h_xx, I am not sure they are dedicated for DP or eDP.

If so, then those register should be no effects after written.


  -        active_hctl = (active_h_end << 16) | active_h_start;
+    intf_cfg |= BIT(29);    /* ACTIVE_H_ENABLE */
+    intf_cfg |= BIT(30);    /* ACTIVE_V_ENABLE */

These were enabled only when active_h_end / active_v_end were non-zero. Any comments?
active_h_end and active_v_end should never be 0.

+
+    active_hctl = (active_h_end << 16) | active_h_start;
+
+    if (dp_intf)
          display_hctl = active_hctl;
-    }
        den_polarity = 0;
      if (ctx->cap->type == INTF_HDMI) {
@@ -204,6 +232,9 @@ static void dpu_hw_intf_setup_timing_engine(struct dpu_hw_intf *ctx,
      DPU_REG_WRITE(c, INTF_FRAME_LINE_COUNT_EN, 0x3);
      DPU_REG_WRITE(c, INTF_CONFIG, intf_cfg);
      DPU_REG_WRITE(c, INTF_PANEL_FORMAT, panel_format);
+    DPU_REG_WRITE(c, INTF_CONFIG2, intf_cfg2);
+    DPU_REG_WRITE(c, INTF_DISPLAY_DATA_HCTL, display_data_hctl);
+    DPU_REG_WRITE(c, INTF_ACTIVE_DATA_HCTL, active_data_hctl);

I see. These writes are currently under the if (ctx->cap->features & BIT(DPU_DATA_HCTL_EN)) condition. Please leave them there unless the condition is wrong.

  }
    static void dpu_hw_intf_enable_timing_engine(
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
index 3568be8..e4a518a 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
@@ -30,6 +30,8 @@ struct intf_timing_params {
      u32 border_clr;
      u32 underflow_clr;
      u32 hsync_skew;
+
+    bool wide_bus_en;
  };
    struct intf_prog_fetch {





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