On Fri, Apr 15, 2016 at 03:47:31PM +0300, Jani Nikula wrote: > Due to "some hardware limitation" the DPI enable bit in port C control > register does not get set on VLV. As a workaround we check the status in > pipe B conf register instead. The workaround was added in > > commit c0beefd29fcb1ca998f0f9ba41be8539f8eeba9b > Author: Gaurav K Singh <gaurav.k.singh@xxxxxxxxx> > Date: Tue Dec 9 10:59:20 2014 +0530 > > drm/i915: Software workaround for getting the HW status of DSI Port C on BYT > > Empirical evidence (on Surface 3 with DSI on port C per VBT) shows that > this is the case also on CHV, so extend the workaround to CHV. We still > have the device ready register check in place, so this should not get > confused with e.g. HDMI on pipe B. > > This fixes a number of state checker warnings on CHV DSI port C. > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_dsi.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c > index 9ff6435e7d38..f57adb0f0ee4 100644 > --- a/drivers/gpu/drm/i915/intel_dsi.c > +++ b/drivers/gpu/drm/i915/intel_dsi.c > @@ -722,11 +722,12 @@ static bool intel_dsi_get_hw_state(struct intel_encoder *encoder, > BXT_MIPI_PORT_CTRL(port) : MIPI_PORT_CTRL(port); > bool enabled = I915_READ(ctrl_reg) & DPI_ENABLE; > > - /* Due to some hardware limitations on BYT, MIPI Port C DPI > - * Enable bit does not get set. To check whether DSI Port C > - * was enabled in BIOS, check the Pipe B enable bit > + /* > + * Due to some hardware limitations on VLV/CHV, the DPI enable > + * bit in port C control register does not get set. As a > + * workaround, check pipe B conf instead. > */ > - if (IS_VALLEYVIEW(dev) && port == PORT_C) > + if ((IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev)) && port == PORT_C) > enabled = I915_READ(PIPECONF(PIPE_B)) & PIPECONF_ENABLE; I saw your register dumps, so I believe it. Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > /* Try command mode if video mode not enabled */ > -- > 2.1.4 -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
