Re: [PATCH] drm/i915: Fix wrong escape clock divisor init for GLK

["Kulkarni, Vandita" <vandita.kulkarni@intel.com>]

> -----Original Message-----
> From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Sent: Wednesday, July 10, 2019 8:04 PM
> To: Lisovskiy, Stanislav <stanislav.lisovskiy@intel.com>; intel-
> gfx@lists.freedesktop.org
> Cc: Peres, Martin <martin.peres@intel.com>; ville.syrjala@linux.intel.com;
> Saarinen, Jani <jani.saarinen@intel.com>; Nikula, Jani <jani.nikula@intel.com>;
> Kulkarni, Vandita <vandita.kulkarni@intel.com>
> Subject: Re: [PATCH] drm/i915: Fix wrong escape clock divisor init for GLK
> 
> Op 10-07-2019 om 16:12 schreef Stanislav Lisovskiy:
> > According to Bspec clock divisor registers in GeminiLake should be
> > initialized by shifting 1(<<) to amount of correspondent divisor.
> > While i915 was writing all this time that value as is.
> >
> > Surprisingly that it by accident worked, until we met some issues with
> > Microtech Etab.
> >
> > Signed-off-by: Stanislav.Lisovskiy@intel.com
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108826
> > ---
> >  drivers/gpu/drm/i915/display/vlv_dsi_pll.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> > b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> > index 99cc3e2e9c2c..f016a776a39e 100644
> > --- a/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> > +++ b/drivers/gpu/drm/i915/display/vlv_dsi_pll.c
> > @@ -396,8 +396,8 @@ static void glk_dsi_program_esc_clock(struct
> drm_device *dev,
> >  	else
> >  		txesc2_div = 10;
> >
> > -	I915_WRITE(MIPIO_TXESC_CLK_DIV1, txesc1_div &
> GLK_TX_ESC_CLK_DIV1_MASK);
> > -	I915_WRITE(MIPIO_TXESC_CLK_DIV2, txesc2_div &
> GLK_TX_ESC_CLK_DIV2_MASK);
> > +	I915_WRITE(MIPIO_TXESC_CLK_DIV1, (1 << (txesc1_div - 1)) &
> GLK_TX_ESC_CLK_DIV1_MASK);
> > +	I915_WRITE(MIPIO_TXESC_CLK_DIV2, (1 << (txesc2_div - 1)) &
> > +GLK_TX_ESC_CLK_DIV2_MASK);
> >  }
The code change looks good to me. With Maarten's comment fixed,

Reviewed-by: Vandita Kulkarni <vandita.kulkarni@intel.com>

Regards,
Vandita
> >
> >  /* Program BXT Mipi clocks and dividers */
> 
> Missing a fixes tag?
> 
> find the original commit that introduced this, then run dim fixes $commitid.
> 
> Cheers,
> 
> Maarten

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