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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
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190524174028.21659-2-hdegoede@redhat.com
(cherry picked from commit 2c1c552526)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Hans de Goede 2019-05-24 19:40:27 +02:00 committed by Jani Nikula
parent d1fdb6d8f6
commit f9a99131ce
3 changed files with 13 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/gpu/drm/i915/intel_display.c
View File

@ -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;

1
drivers/gpu/drm/i915/intel_drv.h
View File

@ -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,

11
drivers/gpu/drm/i915/intel_dsi_vbt.c
View File

@ -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;