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: sta...@vger.kernel.org
Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
drivers/gpu/drm/i915/intel_dsi_vbt.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c
b/drivers/gpu/drm/i915/intel_dsi_vbt.c
index 022bf59418df..a2a9b9d0eeaa 100644
--- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
+++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
@@ -895,6 +895,17 @@ 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
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