From f158b268ddbb3758dec49861bdf3ad8c9aae2e87 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Thu, 29 Nov 2018 12:40:05 +0100
Subject: [PATCH] drm/i915/dsi: Use a fuzzy check for burst mode clock check
Prior to this commit we fail to init the DSI panel on the GPD MicroPC:
https://www.indiegogo.com/projects/gpd-micropc-6-inch-handheld-industry-laptop#/
The problem is intel_dsi_vbt_init() failing with the following error:
*ERROR* Burst mode freq is less than computed
The pclk in the VBT panel modeline is 70000, together with 24 bpp and
4 lines this results in a bitrate value of 70000 * 24 / 4 = 420000.
But the target_burst_mode_freq in the VBT is 418000.
This commit works around this problem by adding an intel_fuzzy_clock_check
when target_burst_mode_freq < bitrate and setting target_burst_mode_freq to
bitrate when that checks succeeds, fixing the panel not working.
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/gpu/drm/i915/intel_display.c | 2 +-
drivers/gpu/drm/i915/intel_drv.h | 1 +
drivers/gpu/drm/i915/intel_dsi_vbt.c | 11 +++++++++++
3 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5098228f1302..ceb78f44f087 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11942,7 +11942,7 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
return 0;
}
-static bool intel_fuzzy_clock_check(int clock1, int clock2)
+bool intel_fuzzy_clock_check(int clock1, int clock2)
{
int diff;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index a38b9cff5cd0..e85cd377a652 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1742,6 +1742,7 @@ int vlv_force_pll_on(struct drm_i915_private *dev_priv, enum pipe pipe,
const struct dpll *dpll);
void vlv_force_pll_off(struct drm_i915_private *dev_priv, enum pipe pipe);
int lpt_get_iclkip(struct drm_i915_private *dev_priv);
+bool intel_fuzzy_clock_check(int clock1, int clock2);
/* modesetting asserts */
void assert_panel_unlocked(struct drm_i915_private *dev_priv,
diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c b/drivers/gpu/drm/i915/intel_dsi_vbt.c
index 3074448446bc..4b8e48db1843 100644
--- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
+++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
@@ -853,6 +853,17 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
if (mipi_config->target_burst_mode_freq) {
u32 bitrate = intel_dsi_bitrate(intel_dsi);
+ /*
+ * Sometimes the VBT contains a slightly lower clock,
+ * then the bitrate we have calculated, in this case
+ * just replace it with the calculated bitrate.
+ */
+ if (mipi_config->target_burst_mode_freq < bitrate &&
+ intel_fuzzy_clock_check(
+ mipi_config->target_burst_mode_freq,
+ bitrate))
+ mipi_config->target_burst_mode_freq = bitrate;
+
if (mipi_config->target_burst_mode_freq < bitrate) {
DRM_ERROR("Burst mode freq is less than computed\n");
return false;
--
2.21.0