linux-kernel - Re: [PATCH] Disable SR when more than one pipe is enabled

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Date:	Thu, 28 Jan 2010 12:28:14 +0530
From:	David John <davidjon@...ontk.org>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
CC:	yakui.zhao@...el.com, linux-kernel@...r.kernel.org,
	Eric Anholt <eric@...olt.net>, stable@...nel.org
Subject: Re: [PATCH] Disable SR when more than one pipe is enabled

On 01/27/2010 10:21 PM, Jesse Barnes wrote:
> On Wed, 27 Jan 2010 15:19:08 +0530
> David John <davidjon@...ontk.org> wrote:
> 
>> Self Refresh should be disabled on dual plane configs.
>> Otherwise, as the SR watermark is not calculated for
>> such configs, switching to non VGA mode causes FIFO
>> underrun and display flicker.
>>
>> This fixes Korg Bug # 14897.
>>
>> Signed-off-by: David John <davidjon@...ontk.org>
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 45da78e..46d7c0c 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -2519,6 +2519,10 @@ static void g4x_update_wm(struct drm_device *dev,  int planea_clock,
>>  		sr_entries = roundup(sr_entries / cacheline_size, 1);
>>  		DRM_DEBUG("self-refresh entries: %d\n", sr_entries);
>>  		I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN);
>> +	} else {
>> +		/* Turn off self refresh if both pipes are enabled */
>> +		I915_WRITE(FW_BLC_SELF, I915_READ(FW_BLC_SELF)
>> +					& ~FW_BLC_SELF_EN);
>>  	}
>>  
>>  	DRM_DEBUG("Setting FIFO watermarks - A: %d, B: %d, SR %d\n",
>> @@ -2562,6 +2566,10 @@ static void i965_update_wm(struct drm_device *dev, int planea_clock,
>>  			srwm = 1;
>>  		srwm &= 0x3f;
>>  		I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN);
>> +	} else {
>> +		/* Turn off self refresh if both pipes are enabled */
>> +		I915_WRITE(FW_BLC_SELF, I915_READ(FW_BLC_SELF)
>> +					& ~FW_BLC_SELF_EN);
>>  	}
>>  
>>  	DRM_DEBUG_KMS("Setting FIFO watermarks - A: 8, B: 8, C: 8, SR %d\n",
>> @@ -2630,6 +2638,10 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
>>  		if (srwm < 0)
>>  			srwm = 1;
>>  		I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN | (srwm & 0x3f));
>> +	} else {
>> +		/* Turn off self refresh if both pipes are enabled */
>> +		I915_WRITE(FW_BLC_SELF, I915_READ(FW_BLC_SELF)
>> +					& ~FW_BLC_SELF_EN);
>>  	}
>>  
>>  	DRM_DEBUG_KMS("Setting FIFO watermarks - A: %d, B: %d, C: %d, SR %d\n",
>>
> 
> Great!  Looks like the docs were a bit misleading here.  Disabling
> self-refresh for dual plane configs is the safest thing to do.
> 
> Eric, please apply asap.  Should probably go to stable as well.
> 
> Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
> 

[ Adding Eric and stable (for 2.6.32 series) to CC]

Regards,
David.
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