Currently the hikey dsi logic cannot generate accurate byte
clocks values for all pixel clock values. Thus if a mode clock
is selected that cannot match the calculated byte clock, the
device will boot with a blank screen.

This patch uses the new mode_valid callback (many thanks to
Jose Abreu for upstreaming it!) to ensure we don't select
modes we cannot generate.

NOTE: Stylistically I suspect there are better ways to do what
I'm trying to do here. The encoder -> crtc bit is terrible, and
getting the crtc adjusted mode from the encoder logic feels
less then ideal. So feedback would be greatly appreciated!

Cc: Daniel Vetter <daniel.vet...@intel.com>
Cc: Jani Nikula <jani.nik...@linux.intel.com>
Cc: Sean Paul <seanp...@chromium.org>
Cc: David Airlie <airl...@linux.ie>
Cc: Rob Clark <robdcl...@gmail.com>
Cc: Xinliang Liu <xinliang....@linaro.org>
Cc: Xinliang Liu <z.liuxinli...@hisilicon.com>
Cc: Rongrong Zou <zourongr...@gmail.com>
Cc: Xinwei Kong <kong.kongxin...@hisilicon.com>
Cc: Chen Feng <puck.c...@hisilicon.com>
Cc: Jose Abreu <jose.ab...@synopsys.com>
Cc: Archit Taneja <arch...@codeaurora.org>
Cc: dri-de...@lists.freedesktop.org
Signed-off-by: John Stultz <john.stu...@linaro.org>
---
v2: Reworked to calculate if modeclock matches the phy's byteclock,
    rather then using a whitelist of known modes.
---
 drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c    | 45 +++++++++++++++++++++++++
 drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c |  8 +++++
 drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h |  2 ++
 3 files changed, 55 insertions(+)

diff --git a/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c 
b/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c
index f77dcfa..9a553e7 100644
--- a/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c
+++ b/drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c
@@ -24,6 +24,7 @@
 #include <drm/drm_encoder_slave.h>
 #include <drm/drm_atomic_helper.h>
 
+#include "kirin_drm_drv.h"
 #include "dw_dsi_reg.h"
 
 #define MAX_TX_ESC_CLK         10
@@ -603,6 +604,49 @@ static void dsi_encoder_enable(struct drm_encoder *encoder)
        dsi->enable = true;
 }
 
+static enum drm_mode_status dsi_encoder_mode_valid(struct drm_encoder *encoder,
+                                       const struct drm_display_mode *mode)
+{
+       struct dw_dsi *dsi = encoder_to_dsi(encoder);
+       struct drm_crtc *crtc = NULL;
+       struct mipi_phy_params phy;
+       u32 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
+       u32 adjusted_clock;
+       u32 req_kHz, act_kHz, lane_byte_clk_kHz;
+
+       /* Figure out what the adjusted modeclock will be */
+       /* XXX There's got to be a better way to go encoder->crtc */
+       drm_for_each_crtc(crtc, encoder->dev)
+               if (crtc)
+                       break;
+       if (crtc)
+               adjusted_clock = kirin_ade_adj_mode_clk(crtc, mode->clock);
+       else
+               adjusted_clock = mode->clock;
+
+       /* Calculate the lane byte clk using the adjusted mode clk */
+       memset(&phy, 0, sizeof(phy));
+       req_kHz = adjusted_clock * bpp / dsi->lanes;
+       act_kHz = dsi_calc_phy_rate(req_kHz, &phy);
+       lane_byte_clk_kHz = act_kHz / 8;
+
+       DRM_DEBUG_DRIVER("Checking mode %ix%i-%i@%i clock: %i adj_clock: %i...",
+                       mode->hdisplay, mode->vdisplay, bpp,
+                       drm_mode_vrefresh(mode), mode->clock, adjusted_clock);
+
+       /*
+        * Make sure the adjused mode clock and the lane byte clk
+        * have a common denominator base frequency
+        */
+       if (adjusted_clock/dsi->lanes == lane_byte_clk_kHz/3) {
+               DRM_DEBUG_DRIVER("OK!\n");
+               return MODE_OK;
+       }
+
+       DRM_DEBUG_DRIVER("BAD!\n");
+       return MODE_BAD;
+}
+
 static void dsi_encoder_mode_set(struct drm_encoder *encoder,
                                 struct drm_display_mode *mode,
                                 struct drm_display_mode *adj_mode)
@@ -622,6 +666,7 @@ static int dsi_encoder_atomic_check(struct drm_encoder 
*encoder,
 
 static const struct drm_encoder_helper_funcs dw_encoder_helper_funcs = {
        .atomic_check   = dsi_encoder_atomic_check,
+       .mode_valid     = dsi_encoder_mode_valid,
        .mode_set       = dsi_encoder_mode_set,
        .enable         = dsi_encoder_enable,
        .disable        = dsi_encoder_disable
diff --git a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c 
b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c
index 074b0af..dffcf76 100644
--- a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c
+++ b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_ade.c
@@ -178,6 +178,14 @@ static void ade_init(struct ade_hw_ctx *ctx)
                        FRM_END_START_MASK, REG_EFFECTIVE_IN_ADEEN_FRMEND);
 }
 
+u32 kirin_ade_adj_mode_clk(struct drm_crtc *crtc, u32 modeclk)
+{
+       struct ade_crtc *acrtc = to_ade_crtc(crtc);
+       struct ade_hw_ctx *ctx = acrtc->ctx;
+
+       return clk_round_rate(ctx->ade_pix_clk, modeclk * 1000) / 1000;
+}
+
 static void ade_set_pix_clk(struct ade_hw_ctx *ctx,
                            struct drm_display_mode *mode,
                            struct drm_display_mode *adj_mode)
diff --git a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h 
b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h
index 7f60c649..85f69ee 100644
--- a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h
+++ b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h
@@ -27,4 +27,6 @@ struct kirin_drm_private {
 
 extern const struct kirin_dc_ops ade_dc_ops;
 
+u32 kirin_ade_adj_mode_clk(struct drm_crtc *crtc, u32 modeclk);
+
 #endif /* __KIRIN_DRM_DRV_H__ */
-- 
2.7.4

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