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

From: Dmitry Baryshkov
Date: Fri Feb 04 2022 - 16:33:43 EST

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__ */
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;

Whitespace changes. Still in place. Move them to the separate commit please.

+
+ 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.
+ */

I think we agreed yesterday during the call, that you'd have separate patches. One for timing changes and another one for wide_bus addition to the timing changes.

+ data_width = p->width;
+
+ if (!dp_intf && p->wide_bus_en)
+ 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
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;
- active_hctl = (active_h_end << 16) | active_h_start;
+ intf_cfg |= BIT(29); /* ACTIVE_H_ENABLE */
+ intf_cfg |= BIT(30); /* ACTIVE_V_ENABLE */
+
+ 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);
}
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 {


--
With best wishes
Dmitry