pending-5.1/drm-i915-dsi-use-a-fuzzy-check-for-burst-mode-clock-check.patch

   1 From f9a99131ce18d9dddcaa14ec2c436e42f0bbee5e Mon Sep 17 00:00:00 2001
   2 From: Hans de Goede <hdegoede@redhat.com>
   3 Date: Fri, 24 May 2019 19:40:27 +0200
   4 Subject: drm/i915/dsi: Use a fuzzy check for burst mode clock check
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   8
   9 From: Hans de Goede <hdegoede@redhat.com>
  10
  11 commit f9a99131ce18d9dddcaa14ec2c436e42f0bbee5e upstream.
  12
  13 Prior to this commit we fail to init the DSI panel on the GPD MicroPC:
  14 https://www.indiegogo.com/projects/gpd-micropc-6-inch-handheld-industry-laptop#/
  15
  16 The problem is intel_dsi_vbt_init() failing with the following error:
  17 *ERROR* Burst mode freq is less than computed
  18
  19 The pclk in the VBT panel modeline is 70000, together with 24 bpp and
  20 4 lines this results in a bitrate value of 70000 * 24 / 4 = 420000.
  21 But the target_burst_mode_freq in the VBT is 418000.
  22
  23 This commit works around this problem by adding an intel_fuzzy_clock_check
  24 when target_burst_mode_freq < bitrate and setting target_burst_mode_freq to
  25 bitrate when that checks succeeds, fixing the panel not working.
  26
  27 Cc: stable@vger.kernel.org
  28 Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
  29 Signed-off-by: Hans de Goede <hdegoede@redhat.com>
  30 Link: https://patchwork.freedesktop.org/patch/msgid/20190524174028.21659-2-hdegoede@redhat.com
  31 (cherry picked from commit 2c1c55252647abd989b94f725b190c700312d053)
  32 Signed-off-by: Jani Nikula <jani.nikula@intel.com>
  33 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  34
  35 ---
  36  drivers/gpu/drm/i915/intel_display.c |    2 +-
  37  drivers/gpu/drm/i915/intel_drv.h     |    1 +
  38  drivers/gpu/drm/i915/intel_dsi_vbt.c |   11 +++++++++++
  39  3 files changed, 13 insertions(+), 1 deletion(-)
  40
  41 --- a/drivers/gpu/drm/i915/intel_display.c
  42 +++ b/drivers/gpu/drm/i915/intel_display.c
  43 @@ -11757,7 +11757,7 @@ encoder_retry:
  44         return 0;
  45  }
  46
  47 -static bool intel_fuzzy_clock_check(int clock1, int clock2)
  48 +bool intel_fuzzy_clock_check(int clock1, int clock2)
  49  {
  50         int diff;
  51
  52 --- a/drivers/gpu/drm/i915/intel_drv.h
  53 +++ b/drivers/gpu/drm/i915/intel_drv.h
  54 @@ -1707,6 +1707,7 @@ int vlv_force_pll_on(struct drm_i915_pri
  55                      const struct dpll *dpll);
  56  void vlv_force_pll_off(struct drm_i915_private *dev_priv, enum pipe pipe);
  57  int lpt_get_iclkip(struct drm_i915_private *dev_priv);
  58 +bool intel_fuzzy_clock_check(int clock1, int clock2);
  59
  60  /* modesetting asserts */
  61  void assert_panel_unlocked(struct drm_i915_private *dev_priv,
  62 --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
  63 +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
  64 @@ -871,6 +871,17 @@ bool intel_dsi_vbt_init(struct intel_dsi
  65                 if (mipi_config->target_burst_mode_freq) {
  66                         u32 bitrate = intel_dsi_bitrate(intel_dsi);
  67
  68 +                       /*
  69 +                        * Sometimes the VBT contains a slightly lower clock,
  70 +                        * then the bitrate we have calculated, in this case
  71 +                        * just replace it with the calculated bitrate.
  72 +                        */
  73 +                       if (mipi_config->target_burst_mode_freq < bitrate &&
  74 +                           intel_fuzzy_clock_check(
  75 +                                       mipi_config->target_burst_mode_freq,
  76 +                                       bitrate))
  77 +                               mipi_config->target_burst_mode_freq = bitrate;
  78 +
  79                         if (mipi_config->target_burst_mode_freq < bitrate) {
  80                                 DRM_ERROR("Burst mode freq is less than computed\n");
  81                                 return false;