Re: [PATCH] drm/i915: Read CHV_PLL_DW8 from the correct offset

From: Todd Previte <tprevite@gmail.com>
To: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Read CHV_PLL_DW8 from the correct offset
Date: Wed, 11 Mar 2015 20:20:44 -0700	[thread overview]
Message-ID: <5501060C.3010205@gmail.com> (raw)
In-Reply-To: <1426107128-779-1-git-send-email-ville.syrjala@linux.intel.com>

On 3/11/2015 1:52 PM, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> We accidentally pass 'pipe' instead of 'port' to CHV_PLL_DW8() and
> with PIPE_C we end up at register offset 0x8320 which isn't the
> 0x8020 we wanted. Fix it.
>
> The problem was fortunately caught by the sanity check in vlv_dpio_read():
> WARNING: CPU: 1 PID: 238 at ../drivers/gpu/drm/i915/intel_sideband.c:200 vlv_dpio_read+0x77/0x80 [i915]()
> DPIO read pipe C reg 0x8320 == 0xffffffff
>
> The problem got introduced with this commit:
>   commit 71af07f91f12bbab96335e202c82525d31680960
>   Author: Vijay Purushothaman <vijay.a.purushothaman@linux.intel.com>
>   Date:   Thu Mar 5 19:33:08 2015 +0530
>
>      drm/i915: Update prop, int co-eff and gain threshold for CHV
>
> Cc: Vijay Purushothaman <vijay.a.purushothaman@linux.intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/intel_display.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index ecbad5a..198e5fc 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6270,7 +6270,7 @@ static void chv_prepare_pll(struct intel_crtc *crtc,
>   	}
>   	vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW6(port), loopfilter);
>   
> -	dpio_val = vlv_dpio_read(dev_priv, pipe, CHV_PLL_DW8(pipe));
> +	dpio_val = vlv_dpio_read(dev_priv, pipe, CHV_PLL_DW8(port));
>   	dpio_val &= ~DPIO_CHV_TDC_TARGET_CNT_MASK;
>   	dpio_val |= (tribuf_calcntr << DPIO_CHV_TDC_TARGET_CNT_SHIFT);
>   	vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW8(port), dpio_val);

Looks good to me.

Reviewed-by: Todd Previte <tprevite@gmail.com>
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