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After the recently added commitfe0f1e3bfd("drm/i915: Shut down displays gracefully on reboot"), the DSI panel on a Cherry Trail based Predia Basic tablet would no longer properly light up after reboot. I've managed to reproduce this without rebooting by doing: chvt 3; echo 1 > /sys/class/graphics/fb0/blank;\ echo 0 > /sys/class/graphics/fb0/blank Which rapidly turns the panel off and back on again. The vlv_dsi.c code uses an intel_dsi_msleep() helper for the various delays used for panel on/off, since starting with MIPI-sequences version >= 3 the delays are already included inside the MIPI-sequences. The problems exposed by the "Shut down displays gracefully on reboot" change, show that using this helper for the panel_pwr_cycle_delay is not the right thing to do. This has not been noticed until now because normally the panel never is cycled off and directly on again in quick succession. Change the msleep for the panel_pwr_cycle_delay to a normal msleep() call to avoid the panel staying black after a quick off + on cycle. Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Fixes:fe0f1e3bfd("drm/i915: Shut down displays gracefully on reboot") Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210325114823.44922-1-hdegoede@redhat.com (cherry picked from commit2878b29fc2) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>