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[PATCH v3 3/3] bus: sunxi-rsb: Clear interrupt status before each transfer

Samuel Holland posted 3 patches 3 years, 4 months ago
[PATCH v3 3/3] bus: sunxi-rsb: Clear interrupt status before each transfer
Posted by Samuel Holland 3 years, 4 months ago 
Currently, the driver clears the interrupt status bits after anything
could have set them. However, this requires duplicating the same logic
in several places.

Instead of clearing the status flags in the interrupt handler, disable
all further interrupts by clearing the RSB_CTRL_GLOBAL_INT_ENB bit.
Then we can delay the status register write until the start of the next
transfer, so it only has to be done in one place.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---

Changes in v3:
 - Add a patch refactoring how the status bits are cleared

 drivers/bus/sunxi-rsb.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index 3aa91aed3bf7..cb622e60897b 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -279,6 +279,7 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
 
 	int_mask = RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR | RSB_INTS_TRANS_OVER;
 	writel(int_mask, rsb->regs + RSB_INTE);
+	writel(int_mask, rsb->regs + RSB_INTS);
 	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
 	       rsb->regs + RSB_CTRL);
 
@@ -286,7 +287,6 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
 		timeout = readl_poll_timeout_atomic(rsb->regs + RSB_INTS,
 						    status, (status & int_mask),
 						    10, 100000);
-		writel(status, rsb->regs + RSB_INTS);
 	} else {
 		timeout = !wait_for_completion_io_timeout(&rsb->complete,
 							  msecs_to_jiffies(100));
@@ -296,12 +296,9 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
 	if (timeout) {
 		dev_dbg(rsb->dev, "RSB timeout\n");
 
-		/* abort the transfer */
+		/* abort the transfer and disable interrupts */
 		writel(RSB_CTRL_ABORT_TRANS, rsb->regs + RSB_CTRL);
 
-		/* clear any interrupt flags */
-		writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
-
 		return -ETIMEDOUT;
 	}
 
@@ -503,15 +500,11 @@ EXPORT_SYMBOL_GPL(__devm_regmap_init_sunxi_rsb);
 static irqreturn_t sunxi_rsb_irq(int irq, void *dev_id)
 {
 	struct sunxi_rsb *rsb = dev_id;
-	u32 status;
 
-	status = readl(rsb->regs + RSB_INTS);
-	rsb->status = status;
+	/* disable interrupts */
+	writel(0, rsb->regs + RSB_CTRL);
 
-	/* Clear interrupts */
-	status &= (RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR |
-		   RSB_INTS_TRANS_OVER);
-	writel(status, rsb->regs + RSB_INTS);
+	rsb->status = readl(rsb->regs + RSB_INTS);
 
 	complete(&rsb->complete);
 
@@ -532,9 +525,6 @@ static int sunxi_rsb_init_device_mode(struct sunxi_rsb *rsb)
 	if (reg & RSB_DMCR_DEVICE_START)
 		ret = -ETIMEDOUT;
 
-	/* clear interrupt status bits */
-	writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
-
 	return ret;
 }
 
-- 
2.37.3
Re: [PATCH v3 3/3] bus: sunxi-rsb: Clear interrupt status before each transfer
Posted by Jernej Škrabec 3 years, 4 months ago 
Hi Samuel,

Dne ponedeljek, 14. november 2022 ob 02:57:49 CET je Samuel Holland 
napisal(a):
> Currently, the driver clears the interrupt status bits after anything
> could have set them. However, this requires duplicating the same logic
> in several places.
> 
> Instead of clearing the status flags in the interrupt handler, disable
> all further interrupts by clearing the RSB_CTRL_GLOBAL_INT_ENB bit.

where is this bit cleared?

> Then we can delay the status register write until the start of the next
> transfer, so it only has to be done in one place.
> 
> Signed-off-by: Samuel Holland <samuel@sholland.org>
> ---
> 
> Changes in v3:
>  - Add a patch refactoring how the status bits are cleared
> 
>  drivers/bus/sunxi-rsb.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
> index 3aa91aed3bf7..cb622e60897b 100644
> --- a/drivers/bus/sunxi-rsb.c
> +++ b/drivers/bus/sunxi-rsb.c
> @@ -279,6 +279,7 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
> 
>  	int_mask = RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR | 
RSB_INTS_TRANS_OVER;
>  	writel(int_mask, rsb->regs + RSB_INTE);
> +	writel(int_mask, rsb->regs + RSB_INTS);

Wouldn't be better to clear status before enabling interrupts? Unless global 
interrupt flag is cleared beforehand, but I don't see that anywhere.

Best regards,
Jernej

>  	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
>  	       rsb->regs + RSB_CTRL);
> 
> @@ -286,7 +287,6 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>  		timeout = readl_poll_timeout_atomic(rsb->regs + 
RSB_INTS,
>  						    status, 
(status & int_mask),
>  						    10, 
100000);
> -		writel(status, rsb->regs + RSB_INTS);
>  	} else {
>  		timeout = !wait_for_completion_io_timeout(&rsb-
>complete,
>  							  
msecs_to_jiffies(100));
> @@ -296,12 +296,9 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>  	if (timeout) {
>  		dev_dbg(rsb->dev, "RSB timeout\n");
> 
> -		/* abort the transfer */
> +		/* abort the transfer and disable interrupts */
>  		writel(RSB_CTRL_ABORT_TRANS, rsb->regs + RSB_CTRL);
> 
> -		/* clear any interrupt flags */
> -		writel(readl(rsb->regs + RSB_INTS), rsb->regs + 
RSB_INTS);
> -
>  		return -ETIMEDOUT;
>  	}
> 
> @@ -503,15 +500,11 @@ EXPORT_SYMBOL_GPL(__devm_regmap_init_sunxi_rsb);
>  static irqreturn_t sunxi_rsb_irq(int irq, void *dev_id)
>  {
>  	struct sunxi_rsb *rsb = dev_id;
> -	u32 status;
> 
> -	status = readl(rsb->regs + RSB_INTS);
> -	rsb->status = status;
> +	/* disable interrupts */
> +	writel(0, rsb->regs + RSB_CTRL);
> 
> -	/* Clear interrupts */
> -	status &= (RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR |
> -		   RSB_INTS_TRANS_OVER);
> -	writel(status, rsb->regs + RSB_INTS);
> +	rsb->status = readl(rsb->regs + RSB_INTS);
> 
>  	complete(&rsb->complete);
> 
> @@ -532,9 +525,6 @@ static int sunxi_rsb_init_device_mode(struct sunxi_rsb
> *rsb) if (reg & RSB_DMCR_DEVICE_START)
>  		ret = -ETIMEDOUT;
> 
> -	/* clear interrupt status bits */
> -	writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
> -
>  	return ret;
>  }
Re: [PATCH v3 3/3] bus: sunxi-rsb: Clear interrupt status before each transfer
Posted by Samuel Holland 3 years, 4 months ago 
On 11/14/22 15:00, Jernej Škrabec wrote:
> Hi Samuel,
> 
> Dne ponedeljek, 14. november 2022 ob 02:57:49 CET je Samuel Holland 
> napisal(a):
>> Currently, the driver clears the interrupt status bits after anything
>> could have set them. However, this requires duplicating the same logic
>> in several places.
>>
>> Instead of clearing the status flags in the interrupt handler, disable
>> all further interrupts by clearing the RSB_CTRL_GLOBAL_INT_ENB bit.
> 
> where is this bit cleared?

It is cleared by any write to RSB_CTRL that does not include it. I noted
it below with the "disable interrupts" comments.

>> Then we can delay the status register write until the start of the next
>> transfer, so it only has to be done in one place.
>>
>> Signed-off-by: Samuel Holland <samuel@sholland.org>
>> ---
>>
>> Changes in v3:
>>  - Add a patch refactoring how the status bits are cleared
>>
>>  drivers/bus/sunxi-rsb.c | 20 +++++---------------
>>  1 file changed, 5 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
>> index 3aa91aed3bf7..cb622e60897b 100644
>> --- a/drivers/bus/sunxi-rsb.c
>> +++ b/drivers/bus/sunxi-rsb.c
>> @@ -279,6 +279,7 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>>
>>  	int_mask = RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR | RSB_INTS_TRANS_OVER;
>>  	writel(int_mask, rsb->regs + RSB_INTE);
>> +	writel(int_mask, rsb->regs + RSB_INTS);
> 
> Wouldn't be better to clear status before enabling interrupts? Unless global 
> interrupt flag is cleared beforehand, but I don't see that anywhere.

Indeed the intention was that the global interrupt flag is cleared
beforehand, and only enabled on the next line below. However, I realize
I missed disabling it for the new atomic case.

I'm not so sure anymore that this patch is an improvement. What do you
think? I can send a v4 with a fix, or I am fine with skipping this
patch. I would at least like the other two to be merged for -fixes.

Regards,
Samuel

>>  	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
>>  	       rsb->regs + RSB_CTRL);
>>
>> @@ -286,7 +287,6 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>>  		timeout = readl_poll_timeout_atomic(rsb->regs + RSB_INTS,
>>  						    status, (status & int_mask),
>>  						    10, 100000);
>> -		writel(status, rsb->regs + RSB_INTS);
>>  	} else {
>>  		timeout = !wait_for_completion_io_timeout(&rsb-
>> complete,
>>  							  msecs_to_jiffies(100));
>> @@ -296,12 +296,9 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
>>  	if (timeout) {
>>  		dev_dbg(rsb->dev, "RSB timeout\n");
>>
>> -		/* abort the transfer */
>> +		/* abort the transfer and disable interrupts */
>>  		writel(RSB_CTRL_ABORT_TRANS, rsb->regs + RSB_CTRL);
>>
>> -		/* clear any interrupt flags */
>> -		writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
>> -
>>  		return -ETIMEDOUT;
>>  	}
>>
>> @@ -503,15 +500,11 @@ EXPORT_SYMBOL_GPL(__devm_regmap_init_sunxi_rsb);
>>  static irqreturn_t sunxi_rsb_irq(int irq, void *dev_id)
>>  {
>>  	struct sunxi_rsb *rsb = dev_id;
>> -	u32 status;
>>
>> -	status = readl(rsb->regs + RSB_INTS);
>> -	rsb->status = status;
>> +	/* disable interrupts */
>> +	writel(0, rsb->regs + RSB_CTRL);
>>
>> -	/* Clear interrupts */
>> -	status &= (RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR |
>> -		   RSB_INTS_TRANS_OVER);
>> -	writel(status, rsb->regs + RSB_INTS);
>> +	rsb->status = readl(rsb->regs + RSB_INTS);
>>
>>  	complete(&rsb->complete);
>>
>> @@ -532,9 +525,6 @@ static int sunxi_rsb_init_device_mode(struct sunxi_rsb
>> *rsb) if (reg & RSB_DMCR_DEVICE_START)
>>  		ret = -ETIMEDOUT;
>>
>> -	/* clear interrupt status bits */
>> -	writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
>> -
>>  	return ret;
>>  }
Re: [PATCH v3 3/3] bus: sunxi-rsb: Clear interrupt status before each transfer
Posted by Jernej Škrabec 3 years, 4 months ago 
Dne torek, 15. november 2022 ob 07:08:12 CET je Samuel Holland napisal(a):
> On 11/14/22 15:00, Jernej Škrabec wrote:
> > Hi Samuel,
> > 
> > Dne ponedeljek, 14. november 2022 ob 02:57:49 CET je Samuel Holland
> > 
> > napisal(a):
> >> Currently, the driver clears the interrupt status bits after anything
> >> could have set them. However, this requires duplicating the same logic
> >> in several places.
> >> 
> >> Instead of clearing the status flags in the interrupt handler, disable
> >> all further interrupts by clearing the RSB_CTRL_GLOBAL_INT_ENB bit.
> > 
> > where is this bit cleared?
> 
> It is cleared by any write to RSB_CTRL that does not include it. I noted
> it below with the "disable interrupts" comments.

Right.

> 
> >> Then we can delay the status register write until the start of the next
> >> transfer, so it only has to be done in one place.
> >> 
> >> Signed-off-by: Samuel Holland <samuel@sholland.org>
> >> ---
> >> 
> >> Changes in v3:
> >>  - Add a patch refactoring how the status bits are cleared
> >>  
> >>  drivers/bus/sunxi-rsb.c | 20 +++++---------------
> >>  1 file changed, 5 insertions(+), 15 deletions(-)
> >> 
> >> diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
> >> index 3aa91aed3bf7..cb622e60897b 100644
> >> --- a/drivers/bus/sunxi-rsb.c
> >> +++ b/drivers/bus/sunxi-rsb.c
> >> @@ -279,6 +279,7 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
> >> 
> >>  	int_mask = RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR |
> >>  	RSB_INTS_TRANS_OVER;
> >>  	writel(int_mask, rsb->regs + RSB_INTE);
> >> 
> >> +	writel(int_mask, rsb->regs + RSB_INTS);
> > 
> > Wouldn't be better to clear status before enabling interrupts? Unless
> > global interrupt flag is cleared beforehand, but I don't see that
> > anywhere.
> Indeed the intention was that the global interrupt flag is cleared
> beforehand, and only enabled on the next line below. However, I realize
> I missed disabling it for the new atomic case.
> 
> I'm not so sure anymore that this patch is an improvement. What do you
> think? I can send a v4 with a fix, or I am fine with skipping this
> patch. I would at least like the other two to be merged for -fixes.

Sure, first two patches will go in regardless. I'm not convinced of value of 
this patch either. I guess we can skip it.

Best regards,
Jernej

> 
> Regards,
> Samuel
> 
> >>  	writel(RSB_CTRL_START_TRANS | RSB_CTRL_GLOBAL_INT_ENB,
> >>  	
> >>  	       rsb->regs + RSB_CTRL);
> >> 
> >> @@ -286,7 +287,6 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb *rsb)
> >> 
> >>  		timeout = readl_poll_timeout_atomic(rsb->regs + 
RSB_INTS,
> >>  		
> >>  						    
status, (status & int_mask),
> >>  						    10, 
100000);
> >> 
> >> -		writel(status, rsb->regs + RSB_INTS);
> >> 
> >>  	} else {
> >>  	
> >>  		timeout = !wait_for_completion_io_timeout(&rsb-
> >> 
> >> complete,
> >> 
> >>  							
  msecs_to_jiffies(100));
> >> 
> >> @@ -296,12 +296,9 @@ static int _sunxi_rsb_run_xfer(struct sunxi_rsb
> >> *rsb)
> >> 
> >>  	if (timeout) {
> >>  	
> >>  		dev_dbg(rsb->dev, "RSB timeout\n");
> >> 
> >> -		/* abort the transfer */
> >> +		/* abort the transfer and disable interrupts */
> >> 
> >>  		writel(RSB_CTRL_ABORT_TRANS, rsb->regs + RSB_CTRL);
> >> 
> >> -		/* clear any interrupt flags */
> >> -		writel(readl(rsb->regs + RSB_INTS), rsb->regs + 
RSB_INTS);
> >> -
> >> 
> >>  		return -ETIMEDOUT;
> >>  	
> >>  	}
> >> 
> >> @@ -503,15 +500,11 @@ EXPORT_SYMBOL_GPL(__devm_regmap_init_sunxi_rsb);
> >> 
> >>  static irqreturn_t sunxi_rsb_irq(int irq, void *dev_id)
> >>  {
> >>  
> >>  	struct sunxi_rsb *rsb = dev_id;
> >> 
> >> -	u32 status;
> >> 
> >> -	status = readl(rsb->regs + RSB_INTS);
> >> -	rsb->status = status;
> >> +	/* disable interrupts */
> >> +	writel(0, rsb->regs + RSB_CTRL);
> >> 
> >> -	/* Clear interrupts */
> >> -	status &= (RSB_INTS_LOAD_BSY | RSB_INTS_TRANS_ERR |
> >> -		   RSB_INTS_TRANS_OVER);
> >> -	writel(status, rsb->regs + RSB_INTS);
> >> +	rsb->status = readl(rsb->regs + RSB_INTS);
> >> 
> >>  	complete(&rsb->complete);
> >> 
> >> @@ -532,9 +525,6 @@ static int sunxi_rsb_init_device_mode(struct
> >> sunxi_rsb
> >> *rsb) if (reg & RSB_DMCR_DEVICE_START)
> >> 
> >>  		ret = -ETIMEDOUT;
> >> 
> >> -	/* clear interrupt status bits */
> >> -	writel(readl(rsb->regs + RSB_INTS), rsb->regs + RSB_INTS);
> >> -
> >> 
> >>  	return ret;
> >>  
> >>  }

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