On Sat, Sep 09, 2017 at 12:10:04AM +0000, Pandiyan, Dhinakaran wrote:
> On Fri, 2017-09-08 at 16:45 -0700, Rodrigo Vivi wrote:
> > Don't touch other bits. My bad.
> >
> > I haven't seen any case where those other bits appeard to be
> > set before we touch it, but it is safe to avoid touching
> > other bits we weren't told to touch.
> >
>
> Well, I did notice the earlier patch cleared rest of the bits, but we do
> the same in ibx_init_clock_gating() and cpt_init_clock_gating() too. So,
> I assume it's okay either way and since these bits are for workarounds,
yep, I believe the old ones were the ones that made me write the initial
version without rmw... but nowadayes we have more components and firmware
with access to register and maybe other chicken bits maybe modified by
other components. so better to start moving to rmw whenever we touch
things like this.
> I thought we might as well start by clearing the bits other than those
> we know are required. But, since you feel this version is a safer
> option,
>
> Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
merged to dinq, thanks for the review.
>
>
> > Fixes: 0a46ddd57c9e ("drm/i915/cnp: Wa 1181: Fix Backlight issue")
> > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_pm.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index fa9055a4f790..09ecc8e3b2d3 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -8370,7 +8370,8 @@ static void cnp_init_clock_gating(struct drm_i915_private *dev_priv)
> > return;
> >
> > /* Wa #1181 */
> > - I915_WRITE(SOUTH_DSPCLK_GATE_D, CNP_PWM_CGE_GATING_DISABLE);
> > + I915_WRITE(SOUTH_DSPCLK_GATE_D, I915_READ(SOUTH_DSPCLK_GATE_D) |
> > + CNP_PWM_CGE_GATING_DISABLE);
> > }
> >
> > static void cnl_init_clock_gating(struct drm_i915_private *dev_priv)
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