[PATCH v2] serial: 8250_of: Fix for lack of interrupt support

[PATCH v2] serial: 8250_of: Fix for lack of interrupt support

[John Garry]

In commit c58caaab3bf8 ("serial: 8250: of: Defer probe on missing IRQ"), a
check was added for the UART driver being probed prior to the parent IRQ
controller.

Unfortunately this breaks certain boards which have no interrupt support,
like Huawei D03.

Indeed, the 8250 DT bindings state that interrupts should be supported -
not must.

To fix, switch from irq_of_parse_and_map() to of_irq_get(), which
does relay whether the IRQ host controller domain is not ready, i.e.
defer probe, instead of assuming it.

Fixes: c58caaab3bf8 ("serial: 8250: of: Defer probe on missing IRQ")
Signed-off-by: John Garry <john.garry@huawei.com>
---

Change in v2:
- fix check on irq value

Note: I think that it would better if we could try to get the interrupt
	  before clk+pm enabling, so we don't need to disable later when
	  deferring, but this is not a fix.

diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index af8beef..877fd7f 100644
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -58,7 +58,7 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 	struct resource resource;
 	struct device_node *np = ofdev->dev.of_node;
 	u32 clk, spd, prop;
-	int ret;
+	int ret, irq;
 
 	memset(port, 0, sizeof *port);
 
@@ -143,21 +143,27 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 	if (ret >= 0)
 		port->line = ret;
 
-	port->irq = irq_of_parse_and_map(np, 0);
-	if (!port->irq) {
-		ret = -EPROBE_DEFER;
-		goto err_unprepare;
+	irq = of_irq_get(np, 0);
+	if (irq < 0) {
+		if (irq == -EPROBE_DEFER) {
+			ret = -EPROBE_DEFER;
+			goto err_unprepare;
+		}
+		/* IRQ support not mandatory */
+		irq = 0;
 	}
 
+	port->irq = irq;
+
 	info->rst = devm_reset_control_get_optional_shared(&ofdev->dev, NULL);
 	if (IS_ERR(info->rst)) {
 		ret = PTR_ERR(info->rst);
-		goto err_dispose;
+		goto err_unprepare;
 	}
 
 	ret = reset_control_deassert(info->rst);
 	if (ret)
-		goto err_dispose;
+		goto err_unprepare;
 
 	port->type = type;
 	port->uartclk = clk;
@@ -184,8 +190,6 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 		port->handle_irq = fsl8250_handle_irq;
 
 	return 0;
-err_dispose:
-	irq_dispose_mapping(port->irq);
 err_unprepare:
 	clk_disable_unprepare(info->clk);
 err_pmruntime:
-- 
1.9.1

Re: [PATCH v2] serial: 8250_of: Fix for lack of interrupt support

[Rob Herring]

On Thu, Aug 30, 2018 at 4:10 AM John Garry <john.garry@huawei.com> wrote:
>
> In commit c58caaab3bf8 ("serial: 8250: of: Defer probe on missing IRQ"), a
> check was added for the UART driver being probed prior to the parent IRQ
> controller.
>
> Unfortunately this breaks certain boards which have no interrupt support,
> like Huawei D03.
>
> Indeed, the 8250 DT bindings state that interrupts should be supported -
> not must.
>
> To fix, switch from irq_of_parse_and_map() to of_irq_get(), which
> does relay whether the IRQ host controller domain is not ready, i.e.
> defer probe, instead of assuming it.

Good, one less user of irq_of_parse_and_map().

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v2] serial: 8250_of: Fix for lack of interrupt support

[Alexander Sverdlin]

Hello John!

On 30/08/2018 11:08, John Garry wrote:
> In commit c58caaab3bf8 ("serial: 8250: of: Defer probe on missing IRQ"), a
> check was added for the UART driver being probed prior to the parent IRQ
> controller.
> 
> Unfortunately this breaks certain boards which have no interrupt support,
> like Huawei D03.
> 
> Indeed, the 8250 DT bindings state that interrupts should be supported -
> not must.
> 
> To fix, switch from irq_of_parse_and_map() to of_irq_get(), which
> does relay whether the IRQ host controller domain is not ready, i.e.
> defer probe, instead of assuming it.
> 
> Fixes: c58caaab3bf8 ("serial: 8250: of: Defer probe on missing IRQ")
> Signed-off-by: John Garry <john.garry@huawei.com>

This indeed looks like a proper way to handle both cases:

Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>

> ---
> 
> Change in v2:
> - fix check on irq value
> 
> Note: I think that it would better if we could try to get the interrupt
> 	  before clk+pm enabling, so we don't need to disable later when
> 	  deferring, but this is not a fix.
> 
> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
> index af8beef..877fd7f 100644
> --- a/drivers/tty/serial/8250/8250_of.c
> +++ b/drivers/tty/serial/8250/8250_of.c
> @@ -58,7 +58,7 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>  	struct resource resource;
>  	struct device_node *np = ofdev->dev.of_node;
>  	u32 clk, spd, prop;
> -	int ret;
> +	int ret, irq;
>  
>  	memset(port, 0, sizeof *port);
>  
> @@ -143,21 +143,27 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>  	if (ret >= 0)
>  		port->line = ret;
>  
> -	port->irq = irq_of_parse_and_map(np, 0);
> -	if (!port->irq) {
> -		ret = -EPROBE_DEFER;
> -		goto err_unprepare;
> +	irq = of_irq_get(np, 0);
> +	if (irq < 0) {
> +		if (irq == -EPROBE_DEFER) {
> +			ret = -EPROBE_DEFER;
> +			goto err_unprepare;
> +		}
> +		/* IRQ support not mandatory */
> +		irq = 0;
>  	}
>  
> +	port->irq = irq;
> +
>  	info->rst = devm_reset_control_get_optional_shared(&ofdev->dev, NULL);
>  	if (IS_ERR(info->rst)) {
>  		ret = PTR_ERR(info->rst);
> -		goto err_dispose;
> +		goto err_unprepare;
>  	}
>  
>  	ret = reset_control_deassert(info->rst);
>  	if (ret)
> -		goto err_dispose;
> +		goto err_unprepare;
>  
>  	port->type = type;
>  	port->uartclk = clk;
> @@ -184,8 +190,6 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>  		port->handle_irq = fsl8250_handle_irq;
>  
>  	return 0;
> -err_dispose:
> -	irq_dispose_mapping(port->irq);
>  err_unprepare:
>  	clk_disable_unprepare(info->clk);
>  err_pmruntime:
> 

-- 
Best regards,
Alexander Sverdlin.

Re: [PATCH v2] serial: 8250_of: Fix for lack of interrupt support

[John Garry]

On 30/08/2018 19:21, Alexander Sverdlin wrote:
> Hello John!
>

Hi Greg,

Can you kindly consider picking up this patch?

It still applies to the branches today in your tty git, but let me know 
if you still rather I resend.

Thanks,
John

> On 30/08/2018 11:08, John Garry wrote:
>> In commit c58caaab3bf8 ("serial: 8250: of: Defer probe on missing IRQ"), a
>> check was added for the UART driver being probed prior to the parent IRQ
>> controller.
>>
>> Unfortunately this breaks certain boards which have no interrupt support,
>> like Huawei D03.
>>
>> Indeed, the 8250 DT bindings state that interrupts should be supported -
>> not must.
>>
>> To fix, switch from irq_of_parse_and_map() to of_irq_get(), which
>> does relay whether the IRQ host controller domain is not ready, i.e.
>> defer probe, instead of assuming it.
>>
>> Fixes: c58caaab3bf8 ("serial: 8250: of: Defer probe on missing IRQ")
>> Signed-off-by: John Garry <john.garry@huawei.com>
>
> This indeed looks like a proper way to handle both cases:
>
> Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
> Tested-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
>
>> ---
>>
>> Change in v2:
>> - fix check on irq value
>>
>> Note: I think that it would better if we could try to get the interrupt
>> 	  before clk+pm enabling, so we don't need to disable later when
>> 	  deferring, but this is not a fix.
>>
>> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
>> index af8beef..877fd7f 100644
>> --- a/drivers/tty/serial/8250/8250_of.c
>> +++ b/drivers/tty/serial/8250/8250_of.c
>> @@ -58,7 +58,7 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>>  	struct resource resource;
>>  	struct device_node *np = ofdev->dev.of_node;
>>  	u32 clk, spd, prop;
>> -	int ret;
>> +	int ret, irq;
>>
>>  	memset(port, 0, sizeof *port);
>>
>> @@ -143,21 +143,27 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>>  	if (ret >= 0)
>>  		port->line = ret;
>>
>> -	port->irq = irq_of_parse_and_map(np, 0);
>> -	if (!port->irq) {
>> -		ret = -EPROBE_DEFER;
>> -		goto err_unprepare;
>> +	irq = of_irq_get(np, 0);
>> +	if (irq < 0) {
>> +		if (irq == -EPROBE_DEFER) {
>> +			ret = -EPROBE_DEFER;
>> +			goto err_unprepare;
>> +		}
>> +		/* IRQ support not mandatory */
>> +		irq = 0;
>>  	}
>>
>> +	port->irq = irq;
>> +
>>  	info->rst = devm_reset_control_get_optional_shared(&ofdev->dev, NULL);
>>  	if (IS_ERR(info->rst)) {
>>  		ret = PTR_ERR(info->rst);
>> -		goto err_dispose;
>> +		goto err_unprepare;
>>  	}
>>
>>  	ret = reset_control_deassert(info->rst);
>>  	if (ret)
>> -		goto err_dispose;
>> +		goto err_unprepare;
>>
>>  	port->type = type;
>>  	port->uartclk = clk;
>> @@ -184,8 +190,6 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>>  		port->handle_irq = fsl8250_handle_irq;
>>
>>  	return 0;
>> -err_dispose:
>> -	irq_dispose_mapping(port->irq);
>>  err_unprepare:
>>  	clk_disable_unprepare(info->clk);
>>  err_pmruntime:
>>
>