[PATCH v9 0/8] Introduce MSM-specific DSC helpers

[PATCH v9 0/8] Introduce MSM-specific DSC helpers

[Jessica Zhang]

There are some overlap in calculations for MSM-specific DSC variables
between DP and DSI. In addition, the calculations for initial_scale_value
and det_thresh_flatness that are defined within the DSC 1.2 specifications,
but aren't yet included in drm_dsc_helper.c.

This series moves these calculations to a shared msm_dsc_helper.c file and
defines drm_dsc_helper methods for initial_scale_value and
det_thresh_flatness.

Note: For now, the MSM specific helper methods are only called for the DSI
path, but will called for DP once DSC 1.2 support for DP has been added.

Depends on: "drm/i915: move DSC RC tables to drm_dsc_helper.c" [1]

[1] https://patchwork.freedesktop.org/series/114472/

---
Changes in v9:
- Fixed incorrect math for msm_dsc_get_bytes_per_line()
- Link to v8: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v8-0-2c9b2bb1209c@quicinc.com

Changes in v8:
- *_bytes_per_soft_slice --> *_bytes_per_slice
- Fixed comment doc formatting for MSM DSC helpers
- Use slice_chunk_size in msm_dsc_get_bytes_per_line calculation
- Reworded "drm/msm/dpu: Use DRM DSC helper for det_thresh_flatness"
  commit title for clarity
- Picked up "Reviewed-by" tags
- Added duplicate Signed-off-by tag to "drm/display/dsc: Add flatness
  and initial scale value calculations" to reflect patch history
- Link to v7: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v7-0-df48a2c54421@quicinc.com

Changes in v7:
- Renamed msm_dsc_get_pclk_per_intf to msm_dsc_get_bytes_per_line
- Removed duplicate msm_dsc_get_dce_bytes_per_line
- Reworded commit message for "drm/msm/dpu: Use DRM DSC helper for
  det_thresh_flatness"
- Dropped slice_per_pkt change (it will be included in the later
  "Add DSC v1.2 Support for DSI" series)
- Picked up "drm/display/dsc: Add flatness and initial scale value
  calculations" and "drm/display/dsc: add helper to set semi-const
  parameters", which were dropped from "drm/i915: move DSC RC tables to
  drm_dsc_helper.c" series
- Picked up "Reviewed-by" tags
- Removed changelog in individual patches
- Link to v6: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v6-0-cb7f59f0f7fb@quicinc.com

Changes in v6:
- Documented return values for MSM DSC helpers
- Fixed dependency issue in msm_dsc_helper.c
- Link to v5: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v5-0-0108401d7886@quicinc.com

Changes in v5:
- Added extra line at end of msm_dsc_helper.h
- Simplified msm_dsc_get_bytes_per_soft_slice() math
- Simplified and inlined msm_dsc_get_pclk_per_intf() math
- "Fix calculations pkt_per_line" --> "... Fix calculation for pkt_per_line"
- Split dsc->slice_width check into a separate patch
- Picked up Dmitry's msm/dsi patch ("drm/msm/dsi: use new helpers for
  DSC setup")
- Removed unused headers in MSM DSC helper files
- Picked up Reviewed-by tags
- Link to v4: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v4-0-1b79c78b30d7@quicinc.com

Changes in v4:
- Changed msm_dsc_get_uncompressed_pclk_per_intf to msm_dsc_get_pclk_per_intf
- Moved pclk_per_intf calculation for dsi_timing_setup to `if
  (msm_host->dsc)` block
- Link to v3: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v3-0-6bec0d277a83@quicinc.com

Changes in v3:
- Dropped src_bpp parameter from all methods -- src_bpp can be
  calculated as dsc->bits_per_component * 3- Cleaned up unused parameters
- Dropped intf_width parameter from get_bytes_per_soft_slice()
- Moved dsc->bits_per_component to numerator calculation in
  get_bytes_per_soft_slice()
- Made get_bytes_per_soft_slice() a public method (this will be called
  later to help calculate DP pclk params)- Added comment documentation to
  MSM DSC helpers
- Renamed msm_dsc_get_uncompressed_pclk_per_line to
  *_get_uncompressed_pclk_per_intf()
- Removed dsc->slice_width check from msm_dsc_get_uncompressed_pclk_per_intf()
- Added documentation in comments
- Moved extra_eol_bytes math out of msm_dsc_get_eol_byte_num()
- Renamed msm_dsc_get_eol_byte_num to *_get_bytes_per_intf.
- Reworded slice_last_group_size calculation to `(dsc->slice_width + 2) % 3`
- Used MSM DSC helper to calculate total_bytes_per_intf
- Initialized hdisplay as uncompressed pclk per line at the beginning of
  dsi_timing_setup as to not break dual DSI calculations
- Added slice_width check to dsi_timing_setup
- Dropped 78c8b81d57d8 ("drm/display/dsc: Add flatness and initial scale
  value calculations") patch as it was absorbed in Dmitry's DSC series [1]
- Split dsi_timing_setup() hdisplay calculation to a separate patch
- Link to v2: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v2-0-3c13ced536b2@quicinc.com

Changes in v2:
- Changed det_thresh_flatness to flatness_det_thresh
- Set initial_scale_value directly in helper
- Moved msm_dsc_helper files to msm/ directory
- Dropped get_comp_ratio() helper
- Used drm_int2fixp() to convert to integers to fp
- Fixed type mismatch issues in MSM DSC helpers
- Changed DSC_BPP macro to drm_dsc_get_bpp_int() helper method
- Style changes to improve readability
- Dropped last division step of msm_dsc_get_pclk_per_line() and changed
  method name accordingly
- Dropped unused bpp variable in msm_dsc_get_dce_bytes_per_line()
- Changed msm_dsc_get_slice_per_intf() to a static inline method
- Split eol_byte_num and pkt_per_line calculation into a separate patch
- Moved pclk_per_line calculation into `if (dsc)` block in
  dsi_timing_setup()
- *_calculate_initial_scale_value --> *_set_initial_scale_value
- Picked up Fixes tags for patches 3/5 and 4/5
- Picked up Reviewed-by for patch 4/5
- Link to v1: https://lore.kernel.org/r/20230329-rfc-msm-dsc-helper-v1-0-f3e479f59b6d@quicinc.com

---
Dmitry Baryshkov (2):
      drm/display/dsc: add helper to set semi-const parameters
      drm/msm/dsi: use DRM DSC helpers for DSC setup

Jessica Zhang (6):
      drm/display/dsc: Add flatness and initial scale value calculations
      drm/msm: Add MSM-specific DSC helper methods
      drm/msm/dpu: Use fixed DRM DSC helper for det_thresh_flatness
      drm/msm/dpu: Fix slice_last_group_size calculation
      drm/msm/dsi: Use MSM and DRM DSC helper methods
      drm/msm/dsi: update hdisplay calculation for dsi_timing_setup

 drivers/gpu/drm/display/drm_dsc_helper.c   | 22 ++++++++++
 drivers/gpu/drm/msm/Makefile               |  1 +
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c |  9 ++--
 drivers/gpu/drm/msm/dsi/dsi_host.c         | 70 ++++++------------------------
 drivers/gpu/drm/msm/msm_dsc_helper.c       | 26 +++++++++++
 drivers/gpu/drm/msm/msm_dsc_helper.h       | 69 +++++++++++++++++++++++++++++
 include/drm/display/drm_dsc_helper.h       | 12 +++++
 7 files changed, 149 insertions(+), 60 deletions(-)
---
base-commit: 5526fe03b40ca1cc72c7b4e97f28d3bbfaa0ded9
change-id: 20230329-rfc-msm-dsc-helper-981a95edfbd0

Best regards,
-- 
Jessica Zhang <quic_jesszhan@quicinc.com>

[PATCH v9 1/8] drm/display/dsc: Add flatness and initial scale value calculations

[Jessica Zhang]

Add helpers to calculate det_thresh_flatness and initial_scale_value as
these calculations are defined within the DSC spec.

Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 include/drm/display/drm_dsc_helper.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/drm/display/drm_dsc_helper.h b/include/drm/display/drm_dsc_helper.h
index 0bb0c3afd740..422135a33d65 100644
--- a/include/drm/display/drm_dsc_helper.h
+++ b/include/drm/display/drm_dsc_helper.h
@@ -25,5 +25,16 @@ void drm_dsc_set_rc_buf_thresh(struct drm_dsc_config *vdsc_cfg);
 int drm_dsc_setup_rc_params(struct drm_dsc_config *vdsc_cfg, enum drm_dsc_params_kind kind);
 int drm_dsc_compute_rc_parameters(struct drm_dsc_config *vdsc_cfg);
 
+static inline void drm_dsc_set_initial_scale_value(struct drm_dsc_config *dsc)
+{
+	dsc->initial_scale_value = 8 * dsc->rc_model_size /
+		(dsc->rc_model_size - dsc->initial_offset);
+}
+
+static inline int drm_dsc_calculate_flatness_det_thresh(struct drm_dsc_config *dsc)
+{
+	return 2 << (dsc->bits_per_component - 8);
+}
+
 #endif /* _DRM_DSC_HELPER_H_ */
 

-- 
2.40.1

[PATCH v9 2/8] drm/display/dsc: add helper to set semi-const parameters

[Jessica Zhang]

From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Add a helper setting config values which are typically constant across
operating modes (table E-4 of the standard) and mux_word_size (which is
a const according to 3.5.2).

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 drivers/gpu/drm/display/drm_dsc_helper.c | 22 ++++++++++++++++++++++
 include/drm/display/drm_dsc_helper.h     |  1 +
 2 files changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dsc_helper.c b/drivers/gpu/drm/display/drm_dsc_helper.c
index 65e810a54257..b9c4e10ced41 100644
--- a/drivers/gpu/drm/display/drm_dsc_helper.c
+++ b/drivers/gpu/drm/display/drm_dsc_helper.c
@@ -270,6 +270,28 @@ void drm_dsc_pps_payload_pack(struct drm_dsc_picture_parameter_set *pps_payload,
 }
 EXPORT_SYMBOL(drm_dsc_pps_payload_pack);
 
+/**
+ * drm_dsc_set_const_params() - Set DSC parameters considered typically
+ * constant across operation modes
+ *
+ * @vdsc_cfg:
+ * DSC Configuration data partially filled by driver
+ */
+void drm_dsc_set_const_params(struct drm_dsc_config *vdsc_cfg)
+{
+	if (!vdsc_cfg->rc_model_size)
+		vdsc_cfg->rc_model_size = DSC_RC_MODEL_SIZE_CONST;
+	vdsc_cfg->rc_edge_factor = DSC_RC_EDGE_FACTOR_CONST;
+	vdsc_cfg->rc_tgt_offset_high = DSC_RC_TGT_OFFSET_HI_CONST;
+	vdsc_cfg->rc_tgt_offset_low = DSC_RC_TGT_OFFSET_LO_CONST;
+
+	if (vdsc_cfg->bits_per_component <= 10)
+		vdsc_cfg->mux_word_size = DSC_MUX_WORD_SIZE_8_10_BPC;
+	else
+		vdsc_cfg->mux_word_size = DSC_MUX_WORD_SIZE_12_BPC;
+}
+EXPORT_SYMBOL(drm_dsc_set_const_params);
+
 /* From DSC_v1.11 spec, rc_parameter_Set syntax element typically constant */
 static const u16 drm_dsc_rc_buf_thresh[] = {
 	896, 1792, 2688, 3584, 4480, 5376, 6272, 6720, 7168, 7616,
diff --git a/include/drm/display/drm_dsc_helper.h b/include/drm/display/drm_dsc_helper.h
index 422135a33d65..bfa7f3acafcb 100644
--- a/include/drm/display/drm_dsc_helper.h
+++ b/include/drm/display/drm_dsc_helper.h
@@ -21,6 +21,7 @@ void drm_dsc_dp_pps_header_init(struct dp_sdp_header *pps_header);
 int drm_dsc_dp_rc_buffer_size(u8 rc_buffer_block_size, u8 rc_buffer_size);
 void drm_dsc_pps_payload_pack(struct drm_dsc_picture_parameter_set *pps_sdp,
 			      const struct drm_dsc_config *dsc_cfg);
+void drm_dsc_set_const_params(struct drm_dsc_config *vdsc_cfg);
 void drm_dsc_set_rc_buf_thresh(struct drm_dsc_config *vdsc_cfg);
 int drm_dsc_setup_rc_params(struct drm_dsc_config *vdsc_cfg, enum drm_dsc_params_kind kind);
 int drm_dsc_compute_rc_parameters(struct drm_dsc_config *vdsc_cfg);

-- 
2.40.1

[PATCH v9 3/8] drm/msm/dsi: use DRM DSC helpers for DSC setup

[Jessica Zhang]

From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Use new DRM DSC helpers to setup DSI DSC configuration. The
initial_scale_value needs to be adjusted according to the standard, but
this is a separate change.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c | 61 +++++---------------------------------
 1 file changed, 8 insertions(+), 53 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 961689a255c4..74d38f90398a 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -1731,28 +1731,9 @@ static int dsi_host_parse_lane_data(struct msm_dsi_host *msm_host,
 	return -EINVAL;
 }
 
-static u32 dsi_dsc_rc_buf_thresh[DSC_NUM_BUF_RANGES - 1] = {
-	0x0e, 0x1c, 0x2a, 0x38, 0x46, 0x54, 0x62,
-	0x69, 0x70, 0x77, 0x79, 0x7b, 0x7d, 0x7e
-};
-
-/* only 8bpc, 8bpp added */
-static char min_qp[DSC_NUM_BUF_RANGES] = {
-	0, 0, 1, 1, 3, 3, 3, 3, 3, 3, 5, 5, 5, 7, 13
-};
-
-static char max_qp[DSC_NUM_BUF_RANGES] = {
-	4, 4, 5, 6, 7, 7, 7, 8, 9, 10, 11, 12, 13, 13, 15
-};
-
-static char bpg_offset[DSC_NUM_BUF_RANGES] = {
-	2, 0, 0, -2, -4, -6, -8, -8, -8, -10, -10, -12, -12, -12, -12
-};
-
 static int dsi_populate_dsc_params(struct msm_dsi_host *msm_host, struct drm_dsc_config *dsc)
 {
-	int i;
-	u16 bpp = dsc->bits_per_pixel >> 4;
+	int ret;
 
 	if (dsc->bits_per_pixel & 0xf) {
 		DRM_DEV_ERROR(&msm_host->pdev->dev, "DSI does not support fractional bits_per_pixel\n");
@@ -1764,49 +1745,23 @@ static int dsi_populate_dsc_params(struct msm_dsi_host *msm_host, struct drm_dsc
 		return -EOPNOTSUPP;
 	}
 
-	dsc->rc_model_size = 8192;
-	dsc->first_line_bpg_offset = 12;
-	dsc->rc_edge_factor = 6;
-	dsc->rc_tgt_offset_high = 3;
-	dsc->rc_tgt_offset_low = 3;
 	dsc->simple_422 = 0;
 	dsc->convert_rgb = 1;
 	dsc->vbr_enable = 0;
 
-	/* handle only bpp = bpc = 8 */
-	for (i = 0; i < DSC_NUM_BUF_RANGES - 1 ; i++)
-		dsc->rc_buf_thresh[i] = dsi_dsc_rc_buf_thresh[i];
+	drm_dsc_set_const_params(dsc);
+	drm_dsc_set_rc_buf_thresh(dsc);
 
-	for (i = 0; i < DSC_NUM_BUF_RANGES; i++) {
-		dsc->rc_range_params[i].range_min_qp = min_qp[i];
-		dsc->rc_range_params[i].range_max_qp = max_qp[i];
-		/*
-		 * Range BPG Offset contains two's-complement signed values that fill
-		 * 8 bits, yet the registers and DCS PPS field are only 6 bits wide.
-		 */
-		dsc->rc_range_params[i].range_bpg_offset = bpg_offset[i] & DSC_RANGE_BPG_OFFSET_MASK;
+	/* handle only bpp = bpc = 8, pre-SCR panels */
+	ret = drm_dsc_setup_rc_params(dsc, DRM_DSC_1_1_PRE_SCR);
+	if (ret) {
+		DRM_DEV_ERROR(&msm_host->pdev->dev, "could not find DSC RC parameters\n");
+		return ret;
 	}
 
-	dsc->initial_offset = 6144;		/* Not bpp 12 */
-	if (bpp != 8)
-		dsc->initial_offset = 2048;	/* bpp = 12 */
-
-	if (dsc->bits_per_component <= 10)
-		dsc->mux_word_size = DSC_MUX_WORD_SIZE_8_10_BPC;
-	else
-		dsc->mux_word_size = DSC_MUX_WORD_SIZE_12_BPC;
-
-	dsc->initial_xmit_delay = 512;
 	dsc->initial_scale_value = 32;
-	dsc->first_line_bpg_offset = 12;
 	dsc->line_buf_depth = dsc->bits_per_component + 1;
 
-	/* bpc 8 */
-	dsc->flatness_min_qp = 3;
-	dsc->flatness_max_qp = 12;
-	dsc->rc_quant_incr_limit0 = 11;
-	dsc->rc_quant_incr_limit1 = 11;
-
 	return drm_dsc_compute_rc_parameters(dsc);
 }
 

-- 
2.40.1

[PATCH v9 4/8] drm/msm: Add MSM-specific DSC helper methods

[Jessica Zhang]

Introduce MSM-specific DSC helper methods, as some calculations are
common between DP and DSC.

Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 drivers/gpu/drm/msm/Makefile         |  1 +
 drivers/gpu/drm/msm/msm_dsc_helper.c | 26 ++++++++++++++
 drivers/gpu/drm/msm/msm_dsc_helper.h | 69 ++++++++++++++++++++++++++++++++++++
 3 files changed, 96 insertions(+)

diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
index 7274c41228ed..b814fc80e2d5 100644
--- a/drivers/gpu/drm/msm/Makefile
+++ b/drivers/gpu/drm/msm/Makefile
@@ -94,6 +94,7 @@ msm-y += \
 	msm_atomic_tracepoints.o \
 	msm_debugfs.o \
 	msm_drv.o \
+	msm_dsc_helper.o \
 	msm_fb.o \
 	msm_fence.o \
 	msm_gem.o \
diff --git a/drivers/gpu/drm/msm/msm_dsc_helper.c b/drivers/gpu/drm/msm/msm_dsc_helper.c
new file mode 100644
index 000000000000..094decad9aea
--- /dev/null
+++ b/drivers/gpu/drm/msm/msm_dsc_helper.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved
+ */
+
+#include <linux/kernel.h>
+#include <drm/drm_fixed.h>
+
+#include "msm_dsc_helper.h"
+
+s64 msm_dsc_get_bytes_per_slice(struct drm_dsc_config *dsc)
+{
+	return drm_fixp_from_fraction(dsc->slice_width * msm_dsc_get_bpp_int(dsc), 8);
+}
+
+u32 msm_dsc_get_bytes_per_intf(struct drm_dsc_config *dsc, int intf_width)
+{
+	u32 bytes_per_slice;
+	s64 bytes_per_slice_fp;
+	int slice_per_intf = msm_dsc_get_slice_per_intf(dsc, intf_width);
+
+	bytes_per_slice_fp = msm_dsc_get_bytes_per_slice(dsc);
+	bytes_per_slice = drm_fixp2int_ceil(bytes_per_slice_fp);
+
+	return bytes_per_slice * slice_per_intf;
+}
diff --git a/drivers/gpu/drm/msm/msm_dsc_helper.h b/drivers/gpu/drm/msm/msm_dsc_helper.h
new file mode 100644
index 000000000000..ba4c57df9f66
--- /dev/null
+++ b/drivers/gpu/drm/msm/msm_dsc_helper.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved
+ */
+
+#ifndef MSM_DSC_HELPER_H_
+#define MSM_DSC_HELPER_H_
+
+#include <linux/bug.h>
+#include <linux/math.h>
+#include <drm/display/drm_dsc_helper.h>
+
+/*
+ * Helper methods for MSM specific DSC calculations that are common between timing engine,
+ * DSI, and DP.
+ */
+
+/**
+ * msm_dsc_get_bpp_int() - get bits per pixel integer value
+ * @dsc: Pointer to drm dsc config struct
+ * Returns: BPP integer value
+ */
+static inline int msm_dsc_get_bpp_int(struct drm_dsc_config *dsc)
+{
+	WARN_ON_ONCE(dsc->bits_per_pixel & 0xf);
+	return dsc->bits_per_pixel >> 4;
+}
+
+/**
+ * msm_dsc_get_slice_per_intf() - get number of slices per interface
+ * @dsc: Pointer to drm dsc config struct
+ * @intf_width: interface width
+ * Returns: Integer representing the slice per interface
+ */
+static inline int msm_dsc_get_slice_per_intf(struct drm_dsc_config *dsc, int intf_width)
+{
+	return DIV_ROUND_UP(intf_width, dsc->slice_width);
+}
+
+/**
+ * msm_dsc_get_bytes_per_line() - Calculate bytes per line
+ * @dsc: Pointer to drm dsc config struct
+ * Returns: Integer value representing pclk per interface
+ *
+ * Note: This value will then be passed along to DSI and DP for some more
+ * calculations. This is because DSI and DP divide the pclk_per_intf value
+ * by different values depending on if widebus is enabled.
+ */
+static inline int msm_dsc_get_bytes_per_line(struct drm_dsc_config *dsc)
+{
+	return dsc->slice_count * dsc->slice_chunk_size;
+}
+
+/**
+ * msm_dsc_get_bytes_per_slice() - get size of each slice for dsc
+ * @dsc: Pointer to drm dsc config struct
+ * Returns: s31.32 fixed point value representing bytes per slice
+ */
+s64 msm_dsc_get_bytes_per_slice(struct drm_dsc_config *dsc);
+
+/**
+ * msm_dsc_get_bytes_per_intf() - get total bytes per interface
+ * @dsc: Pointer to drm dsc config struct
+ * @intf_width: interface width
+ * Returns: u32 value representing bytes per interface
+ */
+u32 msm_dsc_get_bytes_per_intf(struct drm_dsc_config *dsc, int intf_width);
+
+#endif /* MSM_DSC_HELPER_H_ */

-- 
2.40.1

[PATCH v9 5/8] drm/msm/dpu: Use fixed DRM DSC helper for det_thresh_flatness

[Jessica Zhang]

The current dpu_hw_dsc calculation for det_thresh_flatness does not
match the downstream calculation or the DSC spec.

Use the DRM DSC helper for det_thresh_flatness to match downstream
implementation and the DSC spec.

Fixes: c110cfd1753e ("drm/msm/disp/dpu1: Add support for DSC")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
index 4e1396575e6a..1e11c0fb0545 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
@@ -3,6 +3,8 @@
  * Copyright (c) 2020-2022, Linaro Limited
  */
 
+#include <drm/display/drm_dsc_helper.h>
+
 #include "dpu_kms.h"
 #include "dpu_hw_catalog.h"
 #include "dpu_hwio.h"
@@ -102,7 +104,7 @@ static void dpu_hw_dsc_config(struct dpu_hw_dsc *hw_dsc,
 	data |= dsc->final_offset;
 	DPU_REG_WRITE(c, DSC_DSC_OFFSET, data);
 
-	det_thresh_flatness = 7 + 2 * (dsc->bits_per_component - 8);
+	det_thresh_flatness = drm_dsc_calculate_flatness_det_thresh(dsc);
 	data = det_thresh_flatness << 10;
 	data |= dsc->flatness_max_qp << 5;
 	data |= dsc->flatness_min_qp;

-- 
2.40.1

[PATCH v9 6/8] drm/msm/dpu: Fix slice_last_group_size calculation

[Jessica Zhang]

Correct the math for slice_last_group_size so that it matches the
calculations downstream.

Fixes: c110cfd1753e ("drm/msm/disp/dpu1: Add support for DSC")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
index 1e11c0fb0545..ddaec05151cd 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
@@ -56,9 +56,10 @@ static void dpu_hw_dsc_config(struct dpu_hw_dsc *hw_dsc,
 	if (is_cmd_mode)
 		initial_lines += 1;
 
-	slice_last_group_size = 3 - (dsc->slice_width % 3);
+	slice_last_group_size = (dsc->slice_width + 2) % 3;
+
 	data = (initial_lines << 20);
-	data |= ((slice_last_group_size - 1) << 18);
+	data |= (slice_last_group_size << 18);
 	/* bpp is 6.4 format, 4 LSBs bits are for fractional part */
 	data |= (dsc->bits_per_pixel << 8);
 	data |= (dsc->block_pred_enable << 7);

-- 
2.40.1

[PATCH v9 7/8] drm/msm/dsi: Use MSM and DRM DSC helper methods

[Jessica Zhang]

Use MSM and DRM DSC helper methods to configure DSC for DSI.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 74d38f90398a..508577c596ff 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -28,6 +28,7 @@
 #include "dsi.xml.h"
 #include "sfpb.xml.h"
 #include "dsi_cfg.h"
+#include "msm_dsc_helper.h"
 #include "msm_kms.h"
 #include "msm_gem.h"
 #include "phy/dsi_phy.h"
@@ -848,7 +849,7 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod
 	/* first calculate dsc parameters and then program
 	 * compress mode registers
 	 */
-	slice_per_intf = DIV_ROUND_UP(hdisplay, dsc->slice_width);
+	slice_per_intf = msm_dsc_get_slice_per_intf(dsc, hdisplay);
 
 	/*
 	 * If slice_count is greater than slice_per_intf
@@ -858,7 +859,7 @@ static void dsi_update_dsc_timing(struct msm_dsi_host *msm_host, bool is_cmd_mod
 	if (dsc->slice_count > slice_per_intf)
 		dsc->slice_count = 1;
 
-	total_bytes_per_intf = dsc->slice_chunk_size * slice_per_intf;
+	total_bytes_per_intf = msm_dsc_get_bytes_per_intf(dsc, hdisplay);
 
 	eol_byte_num = total_bytes_per_intf % 3;
 	pkt_per_line = slice_per_intf / dsc->slice_count;
@@ -1759,7 +1760,7 @@ static int dsi_populate_dsc_params(struct msm_dsi_host *msm_host, struct drm_dsc
 		return ret;
 	}
 
-	dsc->initial_scale_value = 32;
+	drm_dsc_set_initial_scale_value(dsc);
 	dsc->line_buf_depth = dsc->bits_per_component + 1;
 
 	return drm_dsc_compute_rc_parameters(dsc);

-- 
2.40.1

[PATCH v9 8/8] drm/msm/dsi: update hdisplay calculation for dsi_timing_setup

[Jessica Zhang]

hdisplay for compressed images should be calculated as bytes_per_slice *
slice_count. Thus, use MSM DSC helper to calculate hdisplay for
dsi_timing_setup instead of directly using mode->hdisplay.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 508577c596ff..d60403372514 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -952,7 +952,7 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
 		 * pulse width same
 		 */
 		h_total -= hdisplay;
-		hdisplay /= 3;
+		hdisplay = msm_dsc_get_bytes_per_line(msm_host->dsc) / 3;
 		h_total += hdisplay;
 		ha_end = ha_start + hdisplay;
 	}

-- 
2.40.1

Re: [PATCH v9 1/8] drm/display/dsc: Add flatness and initial scale value calculations

[Ville Syrjälä]

On Wed, May 10, 2023 at 03:54:41PM -0700, Jessica Zhang wrote:
> Add helpers to calculate det_thresh_flatness and initial_scale_value as
> these calculations are defined within the DSC spec.
> 
> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
> ---
>  include/drm/display/drm_dsc_helper.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/include/drm/display/drm_dsc_helper.h b/include/drm/display/drm_dsc_helper.h
> index 0bb0c3afd740..422135a33d65 100644
> --- a/include/drm/display/drm_dsc_helper.h
> +++ b/include/drm/display/drm_dsc_helper.h
> @@ -25,5 +25,16 @@ void drm_dsc_set_rc_buf_thresh(struct drm_dsc_config *vdsc_cfg);
>  int drm_dsc_setup_rc_params(struct drm_dsc_config *vdsc_cfg, enum drm_dsc_params_kind kind);
>  int drm_dsc_compute_rc_parameters(struct drm_dsc_config *vdsc_cfg);
>  
> +static inline void drm_dsc_set_initial_scale_value(struct drm_dsc_config *dsc)
> +{
> +	dsc->initial_scale_value = 8 * dsc->rc_model_size /
> +		(dsc->rc_model_size - dsc->initial_offset);
> +}

I would suggest using pure functions whenever possible. Makes it much
easier to reason about the code when you know there are no side effects.

> +
> +static inline int drm_dsc_calculate_flatness_det_thresh(struct drm_dsc_config *dsc)

'dsc' can be const. The word "calculate" seems pretty much redundant.

> +{
> +	return 2 << (dsc->bits_per_component - 8);
> +}
> +
>  #endif /* _DRM_DSC_HELPER_H_ */
>  
> 
> -- 
> 2.40.1

-- 
Ville Syrjälä
Intel