[RESEND 08/11] pwm: sti: Add support for PWM Capture IRQs

On Wed, Apr 13, 2016 at 11:05:21AM +0100, Lee Jones wrote:

On Tue, 12 Apr 2016, Thierry Reding wrote:

quoted

On Wed, Mar 02, 2016 at 03:32:06PM +0000, Lee Jones wrote:
[...]

quoted

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c

[...]

quoted

quoted

+
+		regmap_read(pc->regmap,
+			    PWM_CPT_VAL(channel), &d->snapshot[d->index]);
+
+		switch (d->index) {
+		case 0:
+		case 1:
+			regmap_read(pc->regmap, PWM_CPT_EDGE(channel), &reg);
+			reg ^= PWM_CPT_EDGE_MASK;
+			regmap_write(pc->regmap, PWM_CPT_EDGE(channel), reg);
+
+			d->index++;
+			break;
+		case 2:
+			regmap_write(pc->regmap,
+				     PWM_CPT_EDGE(channel), CPT_EDGE_DISABLED);
+			wake_up(&d->wait);
+			break;
+		default:
+			dev_err(dev, "Internal error\n");
+		}
+
+		clear_bit(channel, (unsigned long int *)&cpt_int_stat);

clear_bit() is a little unusual to use on regular data types, as
evidenced by the need for the goofy cast here.

It's just a bit neater (and provides locking) than manually bit
twiddling using bitwise operators.  What do you suggest?

I think the cast indicates that you're mixing unrelated interfaces. Also
looking at patch 9/11 it seems like you'll need extra locking to protect
against concurrent accesses in the interrupt handler and the ->capture()
implementation anyway, so might as well use that lock for this access.

quoted

quoted

@@ -371,7 +447,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	struct sti_pwm_chip *pc;
 	struct resource *res;
 	unsigned int chan;
-	int ret;
+	int ret, irq;
 
 	pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
 	if (!pc)

@@ -392,6 +468,19 @@ static int sti_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(pc->regmap))
 		return PTR_ERR(pc->regmap);
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "Failed to obtain IRQ\n");
+		return -ENODEV;
+	}

I think you need to propagate the return value of platform_get_irq()
here.

Yes, could do.  Although, I think we could go either way:

$ git grep -A5 platform_get_irq | grep "return ret\|return irq" | wc -l
176
$ git grep -A5 platform_get_irq | grep "return -EINVAL\|-ENODEV\|-ENXIO" | wc -l
256

Happy to change it though.

I think all the latter are really wrong. Looking at the implementation
of platform_get_irq() there are a number of error codes that it can
return (-EPROBE_DEFER amongst them), so collapsing them all into an
-EINVAL, -ENODEV or -ENXIO is very wrong.

Thierry
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