dsi: refactor bitrate calculations in intel_dsi_vbt_init()

Madhav Chauhan Tue, 16 Oct 2018 05:53:34 -0700

On 10/16/2018 6:14 PM, Jani Nikula wrote:

On Tue, 16 Oct 2018, Madhav Chauhan <madhav.chau...@intel.com> wrote:

On 10/15/2018 7:57 PM, Jani Nikula wrote:

Abstract bitrate calculation to a newly resurrected intel_dsi.c file
that will contain common code for VLV and ICL DSI.


No functional changes.

Cc: Madhav Chauhan <madhav.chau...@intel.com>
Cc: Ville Syrjala <ville.syrj...@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nik...@intel.com>
---
   drivers/gpu/drm/i915/Makefile        |  1 +
   drivers/gpu/drm/i915/intel_dsi.c     | 17 +++++++++++++++++
   drivers/gpu/drm/i915/intel_dsi.h     |  3 +++
   drivers/gpu/drm/i915/intel_dsi_vbt.c | 28 ++++++++++------------------
   4 files changed, 31 insertions(+), 18 deletions(-)
   create mode 100644 drivers/gpu/drm/i915/intel_dsi.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 48cae0eae3f9..22cbf9c3bb0c 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -143,6 +143,7 @@ i915-y += dvo_ch7017.o \
          intel_dp_link_training.o \
          intel_dp_mst.o \
          intel_dp.o \
+         intel_dsi.o \
          intel_dsi_dcs_backlight.o \
          intel_dsi_vbt.o \
          intel_dvo.o \
diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
new file mode 100644
index 000000000000..4daa1da94047
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_dsi.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2018 Intel Corporation
+ */
+
+#include <drm/drm_mipi_dsi.h>
+#include "intel_dsi.h"
+
+int intel_dsi_bitrate(const struct intel_dsi *intel_dsi)
+{
+       int bpp = mipi_dsi_pixel_format_to_bpp(intel_dsi->pixel_format);
+
+       if (WARN_ON(bpp < 0))
+               bpp = 16;

Shouldn't we keep the default bpp to 24 here as in most of the cases bpp
is 24 for DSI or why 16??

*shrug*

Not sure it matters all that much really. We set the pixel format in
intel_dsi_vbt.c, and if that gives us something bogus, not much of a
chance any of it will work. More than anything I just wanted to avoid a
negative return from this function.


Agree,
Reviewed-by: Madhav Chauhan <madhav.chau...@intel.com>

Regards,
Madhav


BR,
Jani.

Regards,
Madhav

+
+       return intel_dsi->pclk * bpp / intel_dsi->lane_count;
+}
diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
index ad7c1cb32983..68f14d8f1e18 100644
--- a/drivers/gpu/drm/i915/intel_dsi.h
+++ b/drivers/gpu/drm/i915/intel_dsi.h
@@ -129,6 +129,9 @@ static inline struct intel_dsi *enc_to_intel_dsi(struct 
drm_encoder *encoder)
        return container_of(encoder, struct intel_dsi, base.base);
   }

+/* intel_dsi.c */

+int intel_dsi_bitrate(const struct intel_dsi *intel_dsi);
+
   /* vlv_dsi.c */
   void vlv_dsi_wait_for_fifo_empty(struct intel_dsi *intel_dsi, enum port 
port);
   enum mipi_dsi_pixel_format pixel_format_from_register_bits(u32 fmt);
diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c 
b/drivers/gpu/drm/i915/intel_dsi_vbt.c
index ac83d6b89ae0..6c4cc92f5947 100644
--- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
+++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
@@ -506,14 +506,12 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 
panel_id)
        struct mipi_config *mipi_config = dev_priv->vbt.dsi.config;
        struct mipi_pps_data *pps = dev_priv->vbt.dsi.pps;
        struct drm_display_mode *mode = dev_priv->vbt.lfp_lvds_vbt_mode;
-       u32 bpp;
-       u32 tlpx_ns, extra_byte_count, bitrate, tlpx_ui;
+       u32 tlpx_ns, extra_byte_count, tlpx_ui;
        u32 ui_num, ui_den;
        u32 prepare_cnt, exit_zero_cnt, clk_zero_cnt, trail_cnt;
        u32 ths_prepare_ns, tclk_trail_ns;
        u32 tclk_prepare_clkzero, ths_prepare_hszero;
        u32 lp_to_hs_switch, hs_to_lp_switch;
-       u32 pclk, computed_ddr;
        u32 mul;
        u16 burst_mode_ratio;
        enum port port;
@@ -526,7 +524,6 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 
panel_id)
        intel_dsi->pixel_format =
                        pixel_format_from_register_bits(
                                mipi_config->videomode_color_format << 7);
-       bpp = mipi_dsi_pixel_format_to_bpp(intel_dsi->pixel_format);

intel_dsi->dual_link = mipi_config->dual_link;

        intel_dsi->pixel_overlap = mipi_config->pixel_overlap;
@@ -541,19 +538,18 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 
panel_id)
        intel_dsi->video_frmt_cfg_bits =
                mipi_config->bta_enabled ? DISABLE_VIDEO_BTA : 0;

- pclk = mode->clock;

+       /* Starting point, adjusted depending on dual link and burst mode */
+       intel_dsi->pclk = mode->clock;

/* In dual link mode each port needs half of pixel clock */

        if (intel_dsi->dual_link) {
-               pclk = pclk / 2;
+               intel_dsi->pclk /= 2;

/* we can enable pixel_overlap if needed by panel. In this

                 * case we need to increase the pixelclock for extra pixels
                 */
                if (intel_dsi->dual_link == DSI_DUAL_LINK_FRONT_BACK) {
-                       pclk += DIV_ROUND_UP(mode->vtotal *
-                                               intel_dsi->pixel_overlap *
-                                               60, 1000);
+                       intel_dsi->pclk += DIV_ROUND_UP(mode->vtotal * 
intel_dsi->pixel_overlap * 60, 1000);
                }
        }

@@ -563,19 +559,18 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)

         */
        if (intel_dsi->video_mode_format == VIDEO_MODE_BURST) {
                if (mipi_config->target_burst_mode_freq) {
-                       computed_ddr = (pclk * bpp) / intel_dsi->lane_count;
+                       u32 bitrate = intel_dsi_bitrate(intel_dsi);

- if (mipi_config->target_burst_mode_freq <

-                                                               computed_ddr) {
+                       if (mipi_config->target_burst_mode_freq < bitrate) {
                                DRM_ERROR("Burst mode freq is less than 
computed\n");
                                return false;
                        }

burst_mode_ratio = DIV_ROUND_UP(

                                mipi_config->target_burst_mode_freq * 100,
-                               computed_ddr);
+                               bitrate);

- pclk = DIV_ROUND_UP(pclk * burst_mode_ratio, 100);

+                       intel_dsi->pclk = DIV_ROUND_UP(intel_dsi->pclk * 
burst_mode_ratio, 100);
                } else {
                        DRM_ERROR("Burst mode target is not set\n");
                        return false;
@@ -584,9 +579,6 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 
panel_id)
                burst_mode_ratio = 100;

intel_dsi->burst_mode_ratio = burst_mode_ratio;

-       intel_dsi->pclk = pclk;
-
-       bitrate = (pclk * bpp) / intel_dsi->lane_count;

switch (intel_dsi->escape_clk_div) {

        case 0:
@@ -620,7 +612,7 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 
panel_id)

/* in Kbps */

        ui_num = NS_KHZ_RATIO;
-       ui_den = bitrate;
+       ui_den = intel_dsi_bitrate(intel_dsi);

tclk_prepare_clkzero = mipi_config->tclk_prepare_clkzero;

        ths_prepare_hszero = mipi_config->ths_prepare_hszero;


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Re: [Intel-gfx] [PATCH v7 02/23] drm/i915/dsi: refactor bitrate calculations in intel_dsi_vbt_init()

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