diff mbox

[1/3,v2] drm/i915: Extract reading INSTDONE

Message ID 1345179901-1161-1-git-send-email-ben@bwidawsk.net (mailing list archive)
State New, archived
Headers show

Commit Message

Ben Widawsky Aug. 17, 2012, 5:05 a.m. UTC
INSTDONE is used in many places, and it varies from generation to
generation. This provides a good reason for us to extract the logic to
read the relevant information.

The patch has no functional change. It's prep for some new stuff.

v2: move the memset inside of i915_get_extra_instdone (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_irq.c | 50 +++++++++++++++++++++++++----------------
 drivers/gpu/drm/i915/i915_reg.h |  1 +
 2 files changed, 32 insertions(+), 19 deletions(-)

Comments

Jani Nikula Aug. 17, 2012, 8:46 a.m. UTC | #1
On Fri, 17 Aug 2012, Ben Widawsky <ben@bwidawsk.net> wrote:
> INSTDONE is used in many places, and it varies from generation to
> generation. This provides a good reason for us to extract the logic to
> read the relevant information.
>
> The patch has no functional change. It's prep for some new stuff.
>
> v2: move the memset inside of i915_get_extra_instdone (Jani)
>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 50 +++++++++++++++++++++++++----------------
>  drivers/gpu/drm/i915/i915_reg.h |  1 +
>  2 files changed, 32 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 0c37101..46eb6e9 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1071,6 +1071,23 @@ i915_error_first_batchbuffer(struct drm_i915_private *dev_priv,
>  	return NULL;
>  }
>  
> +/* NB: please notice the memset */
> +static void i915_get_extra_instdone(struct drm_device *dev,
> +				    uint32_t instdone[I915_NUM_INSTDONE_REG])
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	memset(instdone, 0, sizeof(instdone));

This won't do what you want. sizeof(instdone) == sizeof(uint32_t *)
here. You either have to use I915_NUM_INSTDONE_REG or pass the size.

I don't know what that foo[SIZE] style really is good for in function
parameters. I guess it does have a documentation aspect, and some clever
compilers or static analyzers could flag out of bounds accesses. But it
also gives a kind of false sense of security, and makes one susceptible
to errors like this. So perhaps make that uint32_t *instdone while at
it?

BR,
Jani.

> +
> +	if (INTEL_INFO(dev)->gen < 4) {
> +		instdone[0] = I915_READ(INSTDONE);
> +		instdone[1] = 0;
> +	} else {
> +		instdone[0] = I915_READ(INSTDONE_I965);
> +		instdone[1] = I915_READ(INSTDONE1);
> +	}
> +}
> +
> +
>  static void i915_record_ring_state(struct drm_device *dev,
>  				   struct drm_i915_error_state *error,
>  				   struct intel_ring_buffer *ring)
> @@ -1286,6 +1303,7 @@ void i915_destroy_error_state(struct drm_device *dev)
>  static void i915_report_and_clear_eir(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> +	uint32_t instdone[I915_NUM_INSTDONE_REG];
>  	u32 eir = I915_READ(EIR);
>  	int pipe;
>  
> @@ -1294,16 +1312,17 @@ static void i915_report_and_clear_eir(struct drm_device *dev)
>  
>  	pr_err("render error detected, EIR: 0x%08x\n", eir);
>  
> +	i915_get_extra_instdone(dev, instdone);
> +
>  	if (IS_G4X(dev)) {
>  		if (eir & (GM45_ERROR_MEM_PRIV | GM45_ERROR_CP_PRIV)) {
>  			u32 ipeir = I915_READ(IPEIR_I965);
>  
>  			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR_I965));
>  			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR_I965));
> -			pr_err("  INSTDONE: 0x%08x\n",
> -			       I915_READ(INSTDONE_I965));
> +			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
>  			pr_err("  INSTPS: 0x%08x\n", I915_READ(INSTPS));
> -			pr_err("  INSTDONE1: 0x%08x\n", I915_READ(INSTDONE1));
> +			pr_err("  INSTDONE1: 0x%08x\n", instdone[1]);
>  			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD_I965));
>  			I915_WRITE(IPEIR_I965, ipeir);
>  			POSTING_READ(IPEIR_I965);
> @@ -1342,7 +1361,7 @@ static void i915_report_and_clear_eir(struct drm_device *dev)
>  
>  			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR));
>  			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR));
> -			pr_err("  INSTDONE: 0x%08x\n", I915_READ(INSTDONE));
> +			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
>  			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD));
>  			I915_WRITE(IPEIR, ipeir);
>  			POSTING_READ(IPEIR);
> @@ -1351,10 +1370,9 @@ static void i915_report_and_clear_eir(struct drm_device *dev)
>  
>  			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR_I965));
>  			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR_I965));
> -			pr_err("  INSTDONE: 0x%08x\n",
> -			       I915_READ(INSTDONE_I965));
> +			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
>  			pr_err("  INSTPS: 0x%08x\n", I915_READ(INSTPS));
> -			pr_err("  INSTDONE1: 0x%08x\n", I915_READ(INSTDONE1));
> +			pr_err("  INSTDONE1: 0x%08x\n", instdone[1]);
>  			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD_I965));
>  			I915_WRITE(IPEIR_I965, ipeir);
>  			POSTING_READ(IPEIR_I965);
> @@ -1669,7 +1687,7 @@ void i915_hangcheck_elapsed(unsigned long data)
>  {
>  	struct drm_device *dev = (struct drm_device *)data;
>  	drm_i915_private_t *dev_priv = dev->dev_private;
> -	uint32_t acthd[I915_NUM_RINGS], instdone, instdone1;
> +	uint32_t acthd[I915_NUM_RINGS], instdone[I915_NUM_INSTDONE_REG];
>  	struct intel_ring_buffer *ring;
>  	bool err = false, idle;
>  	int i;
> @@ -1697,25 +1715,19 @@ void i915_hangcheck_elapsed(unsigned long data)
>  		return;
>  	}
>  
> -	if (INTEL_INFO(dev)->gen < 4) {
> -		instdone = I915_READ(INSTDONE);
> -		instdone1 = 0;
> -	} else {
> -		instdone = I915_READ(INSTDONE_I965);
> -		instdone1 = I915_READ(INSTDONE1);
> -	}
> +	i915_get_extra_instdone(dev, instdone);
>  
>  	if (memcmp(dev_priv->last_acthd, acthd, sizeof(acthd)) == 0 &&
> -	    dev_priv->last_instdone == instdone &&
> -	    dev_priv->last_instdone1 == instdone1) {
> +	    dev_priv->last_instdone == instdone[0] &&
> +	    dev_priv->last_instdone1 == instdone[1]) {
>  		if (i915_hangcheck_hung(dev))
>  			return;
>  	} else {
>  		dev_priv->hangcheck_count = 0;
>  
>  		memcpy(dev_priv->last_acthd, acthd, sizeof(acthd));
> -		dev_priv->last_instdone = instdone;
> -		dev_priv->last_instdone1 = instdone1;
> +		dev_priv->last_instdone = instdone[0];
> +		dev_priv->last_instdone1 = instdone[1];
>  	}
>  
>  repeat:
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 321ae72..7ebe6e5 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -478,6 +478,7 @@
>  #define IPEIR_I965	0x02064
>  #define IPEHR_I965	0x02068
>  #define INSTDONE_I965	0x0206c
> +#define I915_NUM_INSTDONE_REG	2
>  #define RING_IPEIR(base)	((base)+0x64)
>  #define RING_IPEHR(base)	((base)+0x68)
>  #define RING_INSTDONE(base)	((base)+0x6c)
> -- 
> 1.7.11.5
Ben Widawsky Aug. 17, 2012, 5:01 p.m. UTC | #2
On 2012-08-17 01:46, Jani Nikula wrote:
> On Fri, 17 Aug 2012, Ben Widawsky <ben@bwidawsk.net> wrote:
>> INSTDONE is used in many places, and it varies from generation to
>> generation. This provides a good reason for us to extract the logic 
>> to
>> read the relevant information.
>>
>> The patch has no functional change. It's prep for some new stuff.
>>
>> v2: move the memset inside of i915_get_extra_instdone (Jani)
>>
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
>> ---
>>  drivers/gpu/drm/i915/i915_irq.c | 50 
>> +++++++++++++++++++++++++----------------
>>  drivers/gpu/drm/i915/i915_reg.h |  1 +
>>  2 files changed, 32 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_irq.c 
>> b/drivers/gpu/drm/i915/i915_irq.c
>> index 0c37101..46eb6e9 100644
>> --- a/drivers/gpu/drm/i915/i915_irq.c
>> +++ b/drivers/gpu/drm/i915/i915_irq.c
>> @@ -1071,6 +1071,23 @@ i915_error_first_batchbuffer(struct 
>> drm_i915_private *dev_priv,
>>  	return NULL;
>>  }
>>
>> +/* NB: please notice the memset */
>> +static void i915_get_extra_instdone(struct drm_device *dev,
>> +				    uint32_t instdone[I915_NUM_INSTDONE_REG])
>> +{
>> +	struct drm_i915_private *dev_priv = dev->dev_private;
>> +	memset(instdone, 0, sizeof(instdone));
>
> This won't do what you want. sizeof(instdone) == sizeof(uint32_t *)
> here. You either have to use I915_NUM_INSTDONE_REG or pass the size.

Ooops; now that I've made myself look properly bad... Or I could call 
memset outside of the function :-)

>
> I don't know what that foo[SIZE] style really is good for in function
> parameters. I guess it does have a documentation aspect, and some 
> clever
> compilers or static analyzers could flag out of bounds accesses. But 
> it
> also gives a kind of false sense of security, and makes one 
> susceptible
> to errors like this. So perhaps make that uint32_t *instdone while at
> it?
>
> BR,
> Jani.

Well, I liked it for documentation and because I thought gcc could do 
the right thing with it, ie. make the sizeof stuff work correctly. Since 
it doesn't, I'm left not caring; and I just want to get an r-b. So I'll 
do it how you asked.

>
>> +
>> +	if (INTEL_INFO(dev)->gen < 4) {
>> +		instdone[0] = I915_READ(INSTDONE);
>> +		instdone[1] = 0;
>> +	} else {
>> +		instdone[0] = I915_READ(INSTDONE_I965);
>> +		instdone[1] = I915_READ(INSTDONE1);
>> +	}
>> +}
>> +
>> +
>>  static void i915_record_ring_state(struct drm_device *dev,
>>  				   struct drm_i915_error_state *error,
>>  				   struct intel_ring_buffer *ring)
>> @@ -1286,6 +1303,7 @@ void i915_destroy_error_state(struct 
>> drm_device *dev)
>>  static void i915_report_and_clear_eir(struct drm_device *dev)
>>  {
>>  	struct drm_i915_private *dev_priv = dev->dev_private;
>> +	uint32_t instdone[I915_NUM_INSTDONE_REG];
>>  	u32 eir = I915_READ(EIR);
>>  	int pipe;
>>
>> @@ -1294,16 +1312,17 @@ static void i915_report_and_clear_eir(struct 
>> drm_device *dev)
>>
>>  	pr_err("render error detected, EIR: 0x%08x\n", eir);
>>
>> +	i915_get_extra_instdone(dev, instdone);
>> +
>>  	if (IS_G4X(dev)) {
>>  		if (eir & (GM45_ERROR_MEM_PRIV | GM45_ERROR_CP_PRIV)) {
>>  			u32 ipeir = I915_READ(IPEIR_I965);
>>
>>  			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR_I965));
>>  			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR_I965));
>> -			pr_err("  INSTDONE: 0x%08x\n",
>> -			       I915_READ(INSTDONE_I965));
>> +			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
>>  			pr_err("  INSTPS: 0x%08x\n", I915_READ(INSTPS));
>> -			pr_err("  INSTDONE1: 0x%08x\n", I915_READ(INSTDONE1));
>> +			pr_err("  INSTDONE1: 0x%08x\n", instdone[1]);
>>  			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD_I965));
>>  			I915_WRITE(IPEIR_I965, ipeir);
>>  			POSTING_READ(IPEIR_I965);
>> @@ -1342,7 +1361,7 @@ static void i915_report_and_clear_eir(struct 
>> drm_device *dev)
>>
>>  			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR));
>>  			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR));
>> -			pr_err("  INSTDONE: 0x%08x\n", I915_READ(INSTDONE));
>> +			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
>>  			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD));
>>  			I915_WRITE(IPEIR, ipeir);
>>  			POSTING_READ(IPEIR);
>> @@ -1351,10 +1370,9 @@ static void i915_report_and_clear_eir(struct 
>> drm_device *dev)
>>
>>  			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR_I965));
>>  			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR_I965));
>> -			pr_err("  INSTDONE: 0x%08x\n",
>> -			       I915_READ(INSTDONE_I965));
>> +			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
>>  			pr_err("  INSTPS: 0x%08x\n", I915_READ(INSTPS));
>> -			pr_err("  INSTDONE1: 0x%08x\n", I915_READ(INSTDONE1));
>> +			pr_err("  INSTDONE1: 0x%08x\n", instdone[1]);
>>  			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD_I965));
>>  			I915_WRITE(IPEIR_I965, ipeir);
>>  			POSTING_READ(IPEIR_I965);
>> @@ -1669,7 +1687,7 @@ void i915_hangcheck_elapsed(unsigned long 
>> data)
>>  {
>>  	struct drm_device *dev = (struct drm_device *)data;
>>  	drm_i915_private_t *dev_priv = dev->dev_private;
>> -	uint32_t acthd[I915_NUM_RINGS], instdone, instdone1;
>> +	uint32_t acthd[I915_NUM_RINGS], instdone[I915_NUM_INSTDONE_REG];
>>  	struct intel_ring_buffer *ring;
>>  	bool err = false, idle;
>>  	int i;
>> @@ -1697,25 +1715,19 @@ void i915_hangcheck_elapsed(unsigned long 
>> data)
>>  		return;
>>  	}
>>
>> -	if (INTEL_INFO(dev)->gen < 4) {
>> -		instdone = I915_READ(INSTDONE);
>> -		instdone1 = 0;
>> -	} else {
>> -		instdone = I915_READ(INSTDONE_I965);
>> -		instdone1 = I915_READ(INSTDONE1);
>> -	}
>> +	i915_get_extra_instdone(dev, instdone);
>>
>>  	if (memcmp(dev_priv->last_acthd, acthd, sizeof(acthd)) == 0 &&
>> -	    dev_priv->last_instdone == instdone &&
>> -	    dev_priv->last_instdone1 == instdone1) {
>> +	    dev_priv->last_instdone == instdone[0] &&
>> +	    dev_priv->last_instdone1 == instdone[1]) {
>>  		if (i915_hangcheck_hung(dev))
>>  			return;
>>  	} else {
>>  		dev_priv->hangcheck_count = 0;
>>
>>  		memcpy(dev_priv->last_acthd, acthd, sizeof(acthd));
>> -		dev_priv->last_instdone = instdone;
>> -		dev_priv->last_instdone1 = instdone1;
>> +		dev_priv->last_instdone = instdone[0];
>> +		dev_priv->last_instdone1 = instdone[1];
>>  	}
>>
>>  repeat:
>> diff --git a/drivers/gpu/drm/i915/i915_reg.h 
>> b/drivers/gpu/drm/i915/i915_reg.h
>> index 321ae72..7ebe6e5 100644
>> --- a/drivers/gpu/drm/i915/i915_reg.h
>> +++ b/drivers/gpu/drm/i915/i915_reg.h
>> @@ -478,6 +478,7 @@
>>  #define IPEIR_I965	0x02064
>>  #define IPEHR_I965	0x02068
>>  #define INSTDONE_I965	0x0206c
>> +#define I915_NUM_INSTDONE_REG	2
>>  #define RING_IPEIR(base)	((base)+0x64)
>>  #define RING_IPEHR(base)	((base)+0x68)
>>  #define RING_INSTDONE(base)	((base)+0x6c)
>> --
>> 1.7.11.5
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 0c37101..46eb6e9 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1071,6 +1071,23 @@  i915_error_first_batchbuffer(struct drm_i915_private *dev_priv,
 	return NULL;
 }
 
+/* NB: please notice the memset */
+static void i915_get_extra_instdone(struct drm_device *dev,
+				    uint32_t instdone[I915_NUM_INSTDONE_REG])
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	memset(instdone, 0, sizeof(instdone));
+
+	if (INTEL_INFO(dev)->gen < 4) {
+		instdone[0] = I915_READ(INSTDONE);
+		instdone[1] = 0;
+	} else {
+		instdone[0] = I915_READ(INSTDONE_I965);
+		instdone[1] = I915_READ(INSTDONE1);
+	}
+}
+
+
 static void i915_record_ring_state(struct drm_device *dev,
 				   struct drm_i915_error_state *error,
 				   struct intel_ring_buffer *ring)
@@ -1286,6 +1303,7 @@  void i915_destroy_error_state(struct drm_device *dev)
 static void i915_report_and_clear_eir(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t instdone[I915_NUM_INSTDONE_REG];
 	u32 eir = I915_READ(EIR);
 	int pipe;
 
@@ -1294,16 +1312,17 @@  static void i915_report_and_clear_eir(struct drm_device *dev)
 
 	pr_err("render error detected, EIR: 0x%08x\n", eir);
 
+	i915_get_extra_instdone(dev, instdone);
+
 	if (IS_G4X(dev)) {
 		if (eir & (GM45_ERROR_MEM_PRIV | GM45_ERROR_CP_PRIV)) {
 			u32 ipeir = I915_READ(IPEIR_I965);
 
 			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR_I965));
 			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR_I965));
-			pr_err("  INSTDONE: 0x%08x\n",
-			       I915_READ(INSTDONE_I965));
+			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
 			pr_err("  INSTPS: 0x%08x\n", I915_READ(INSTPS));
-			pr_err("  INSTDONE1: 0x%08x\n", I915_READ(INSTDONE1));
+			pr_err("  INSTDONE1: 0x%08x\n", instdone[1]);
 			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD_I965));
 			I915_WRITE(IPEIR_I965, ipeir);
 			POSTING_READ(IPEIR_I965);
@@ -1342,7 +1361,7 @@  static void i915_report_and_clear_eir(struct drm_device *dev)
 
 			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR));
 			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR));
-			pr_err("  INSTDONE: 0x%08x\n", I915_READ(INSTDONE));
+			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
 			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD));
 			I915_WRITE(IPEIR, ipeir);
 			POSTING_READ(IPEIR);
@@ -1351,10 +1370,9 @@  static void i915_report_and_clear_eir(struct drm_device *dev)
 
 			pr_err("  IPEIR: 0x%08x\n", I915_READ(IPEIR_I965));
 			pr_err("  IPEHR: 0x%08x\n", I915_READ(IPEHR_I965));
-			pr_err("  INSTDONE: 0x%08x\n",
-			       I915_READ(INSTDONE_I965));
+			pr_err("  INSTDONE: 0x%08x\n", instdone[0]);
 			pr_err("  INSTPS: 0x%08x\n", I915_READ(INSTPS));
-			pr_err("  INSTDONE1: 0x%08x\n", I915_READ(INSTDONE1));
+			pr_err("  INSTDONE1: 0x%08x\n", instdone[1]);
 			pr_err("  ACTHD: 0x%08x\n", I915_READ(ACTHD_I965));
 			I915_WRITE(IPEIR_I965, ipeir);
 			POSTING_READ(IPEIR_I965);
@@ -1669,7 +1687,7 @@  void i915_hangcheck_elapsed(unsigned long data)
 {
 	struct drm_device *dev = (struct drm_device *)data;
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	uint32_t acthd[I915_NUM_RINGS], instdone, instdone1;
+	uint32_t acthd[I915_NUM_RINGS], instdone[I915_NUM_INSTDONE_REG];
 	struct intel_ring_buffer *ring;
 	bool err = false, idle;
 	int i;
@@ -1697,25 +1715,19 @@  void i915_hangcheck_elapsed(unsigned long data)
 		return;
 	}
 
-	if (INTEL_INFO(dev)->gen < 4) {
-		instdone = I915_READ(INSTDONE);
-		instdone1 = 0;
-	} else {
-		instdone = I915_READ(INSTDONE_I965);
-		instdone1 = I915_READ(INSTDONE1);
-	}
+	i915_get_extra_instdone(dev, instdone);
 
 	if (memcmp(dev_priv->last_acthd, acthd, sizeof(acthd)) == 0 &&
-	    dev_priv->last_instdone == instdone &&
-	    dev_priv->last_instdone1 == instdone1) {
+	    dev_priv->last_instdone == instdone[0] &&
+	    dev_priv->last_instdone1 == instdone[1]) {
 		if (i915_hangcheck_hung(dev))
 			return;
 	} else {
 		dev_priv->hangcheck_count = 0;
 
 		memcpy(dev_priv->last_acthd, acthd, sizeof(acthd));
-		dev_priv->last_instdone = instdone;
-		dev_priv->last_instdone1 = instdone1;
+		dev_priv->last_instdone = instdone[0];
+		dev_priv->last_instdone1 = instdone[1];
 	}
 
 repeat:
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 321ae72..7ebe6e5 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -478,6 +478,7 @@ 
 #define IPEIR_I965	0x02064
 #define IPEHR_I965	0x02068
 #define INSTDONE_I965	0x0206c
+#define I915_NUM_INSTDONE_REG	2
 #define RING_IPEIR(base)	((base)+0x64)
 #define RING_IPEHR(base)	((base)+0x68)
 #define RING_INSTDONE(base)	((base)+0x6c)