On Wed, 2015-04-01 at 14:22 -0700, Jesse Barnes wrote: > Looks like it was introduced in: > > commit 650ad970a39f8b6164fe8613edc150f585315289 > Author: Imre Deak <imre.d...@intel.com> > Date: Fri Apr 18 16:35:02 2014 +0300 > > drm/i915: vlv: factor out vlv_force_gfx_clock and check for pending > force-of > > but I'm not sure why. It has caused problems for us in the past (see > 85250ddff7a603dfe0ec0503a9e6395f79424f61 and > 8d4eee9cd7a170342dc6fbc2ee19ae77031a8cd5) and doesn't seem to be > required, so let's just drop it. > > References: https://bugs.freedesktop.org/show_bug.cgi?id=89611 > Signed-off-by: Jesse Barnes <jbar...@virtuousgeek.org> > --- > drivers/gpu/drm/i915/i915_drv.c | 14 -------------- > 1 file changed, 14 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c > index 4d6d6f0..c3fdbb0 100644 > --- a/drivers/gpu/drm/i915/i915_drv.c > +++ b/drivers/gpu/drm/i915/i915_drv.c > @@ -1208,21 +1208,7 @@ int vlv_force_gfx_clock(struct drm_i915_private > *dev_priv, bool force_on) > u32 val; > int err; > > - val = I915_READ(VLV_GTLC_SURVIVABILITY_REG); > - > #define COND (I915_READ(VLV_GTLC_SURVIVABILITY_REG) & VLV_GFX_CLK_STATUS_BIT) > - /* Wait for a previous force-off to settle */ > - if (force_on && !IS_CHERRYVIEW(dev_priv->dev)) { > - /* WARN_ON only for the Valleyview */ > - WARN_ON(!!(val & VLV_GFX_CLK_FORCE_ON_BIT) == force_on); > - > - err = wait_for(!COND, 20); > - if (err) { > - DRM_ERROR("timeout waiting for GFX clock force-off > (%08x)\n", > - I915_READ(VLV_GTLC_SURVIVABILITY_REG)); > - return err; > - } > - }
The reason I added this is that it's not clear what happens if you try to force the clock on while the previous force-off operation is still pending. That is if Punit will correctly cancel turning off the clock in this case. Since the docs don't clarify this either I thought the above is safer. Is it the WARN that triggers and only during resume (we also call the function from vlv_set_rps_idle)? If so, then it's not a real timeout but BIOS has left the force-on flag set and we could just skip calling vlv_force_gfx_clock(true) in that case. If the HW people can confirm that the above isn't needed then I'm also ok to remove it. > > val = I915_READ(VLV_GTLC_SURVIVABILITY_REG); > val &= ~VLV_GFX_CLK_FORCE_ON_BIT; _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
