On 4/21/2016 1:07 PM, Chris Wilson wrote:
On Thu, Apr 21, 2016 at 12:33:41PM +0530, akash.goel@xxxxxxxxx wrote:From: Akash Goel <akash.goel@xxxxxxxxx> As a part of WaGsvDisableTurbo, Driver makes an early exit from the Gen9 Turbo enabling function, so doesn't program the Turbo Control register. But BIOS could leave the Hw Turbo as enabled, so need to explicitly clear out the Control register just to avoid inconsitency with debugfs interface, which will show Turbo as enabled only and that is not expected after adding the WaGsvDisableTurbo. Apart from this there is no problem even if the Turbo is left enabled in the Control register, as the Up/Down interrupts would remain masked. Signed-off-by: Akash Goel <akash.goel@xxxxxxxxx> --- drivers/gpu/drm/i915/intel_pm.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index b7c2186..41d5586 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -4804,6 +4804,16 @@ static void gen9_enable_rps(struct drm_device *dev) /* WaGsvDisableTurbo: Workaround to disable turbo on BXT A* */ if (IS_BXT_REVID(dev, 0, BXT_REVID_A1)) { + /* + * BIOS could leave the Hw Turbo enabled, so need to explicitly + * clear out the Control register just to avoid inconsitency + * with debugfs interface, which will show Turbo as enabled + * only and that is not expected by the User after adding the + * WaGsvDisableTurbo. Apart from this there is no problem even + * if the Turbo is left enabled in the Control register, as the + * Up/Down interrupts would remain masked. + */ + I915_WRITE(GEN6_RP_CONTROL, 0);First question. Do we not want to sanitize bios state for everybody during init? That is the usual procedure.
Sorry I am not sure. There is a sanitize for certain module parameters. Recently for RC6 on BXT, sanitize was done depending upon the BIOS state.
None of the *_disable_rps() actually clear GEN6_RP_CONTROL. They should according to the rationale above. And then this should be a call to gen9_disable_rps().
Ok so will add the clearing of GEN6_RP_CONTROL in all *_disable_rps() and then call gen9_disable_rps().
Best regards Akash
-Chris
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