Re: [PATCH 5/7] drm/i915/cnl: Don't blindly replace qdiv.

From: Manasi Navare <manasi.d.navare@intel.com>
To: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 5/7] drm/i915/cnl: Don't blindly replace qdiv.
Date: Tue, 14 Nov 2017 15:34:41 -0800	[thread overview]
Message-ID: <20171114233440.GC18077@intel.com> (raw)
In-Reply-To: <20171114194759.24541-6-rodrigo.vivi@intel.com>

On Tue, Nov 14, 2017 at 11:47:57AM -0800, Rodrigo Vivi wrote:
> Accordingly to spec "If Kdiv != 2, then Qdiv must be 1."
> but we already handle qdiv values properly and this case here
> should be spurious. But instead of blindly replacing let's
> warn loudly instead. Because it means something was really
> wrong on initial setup.
> 
> Cc: Mika Kahola <mika.kahola@intel.com>
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Cc: James Ausmus <james.ausmus@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_dpll_mgr.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> index 53f650f56148..bd608f7f2399 100644
> --- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
> +++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
> @@ -2184,8 +2184,7 @@ static void cnl_wrpll_params_populate(struct skl_wrpll_params *params,
>  		WARN(1, "Incorrect PDiv\n");
>  	}
>  
> -	if (kdiv != 2)
> -		qdiv = 1;
> +	WARN_ON(kdiv != 2 && qdiv != 1);
>  
>  	params->qdiv_ratio = qdiv;
>  	params->qdiv_mode = (qdiv == 1) ? 0 : 1;
> -- 
> 2.13.6
> 
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