[PATCH v2 0/3] Fix deferred probing in the I2C bus drivers

[PATCH v2 0/3] Fix deferred probing in the I2C bus drivers

[Sergey Shtylyov]

Here are 3 patches against the 'i2c/for-current' branch of Wolfram's 'linux.git' repo.
The affected drivers call platform_get_irq() but override its result in case of error
which prevents the deferred probing from working.

[1/3] i2c: iop3xx: fix deferred probing
[2/3] i2c: pca-platform: fix deferred probing
[3/3] i2c: synquacer: fix deferred probing

[PATCH v2 1/3] i2c: iop3xx: fix deferred probing

[Sergey Shtylyov]

When adding the code to handle platform_get_irq*() errors in the commit
489447380a29 ("[PATCH] handle errors returned by platform_get_irq*()"),
the actual error code was enforced to be -ENXIO in the driver for some
strange reason.  This didn't matter much until the deferred probing was
introduced -- which requires an actual error code to be propagated
upstream from the failure site.

While fixing this, also stop overriding the errors from request_irq() to
-EIO (done since the pre-git era).

Fixes: 489447380a29 ("[PATCH] handle errors returned by platform_get_irq*()")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

---
Changed in version 2:
- added an article and a space to the patch description;
- updated domain in the OMP email addresses.

 drivers/i2c/busses/i2c-iop3xx.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Index: linux/drivers/i2c/busses/i2c-iop3xx.c
===================================================================
--- linux.orig/drivers/i2c/busses/i2c-iop3xx.c
+++ linux/drivers/i2c/busses/i2c-iop3xx.c
@@ -467,16 +467,14 @@ iop3xx_i2c_probe(struct platform_device
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
-		ret = -ENXIO;
+		ret = irq;
 		goto unmap;
 	}
 	ret = request_irq(irq, iop3xx_i2c_irq_handler, 0,
 				pdev->name, adapter_data);
 
-	if (ret) {
-		ret = -EIO;
+	if (ret)
 		goto unmap;
-	}
 
 	memcpy(new_adapter->name, pdev->name, strlen(pdev->name));
 	new_adapter->owner = THIS_MODULE;

[PATCH v2 2/3] i2c: pca-platform: fix deferred probing

[Sergey Shtylyov]

The driver's probe() method chooses the polling mode if an IRQ # returned
by platform_get_irq_optional() is 0 or  less.  We'll have to filter out
-EPROBE_DEFER earlier for the deferred probing to work...

Fixes: 0e8ce93bdceb ("i2c: pca-platform: add devicetree awareness")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

---
Changed in version 2:
- new patch.

 drivers/i2c/busses/i2c-pca-platform.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux/drivers/i2c/busses/i2c-pca-platform.c
===================================================================
--- linux.orig/drivers/i2c/busses/i2c-pca-platform.c
+++ linux/drivers/i2c/busses/i2c-pca-platform.c
@@ -139,6 +139,8 @@ static int i2c_pca_pf_probe(struct platf
 	int irq;
 
 	irq = platform_get_irq_optional(pdev, 0);
+	if (irq == -EPROBE_DEFER)
+		return irq;
 	/* If irq is 0, we do polling. */
 	if (irq < 0)
 		irq = 0;

[PATCH v2 3/3] i2c: synquacer: fix deferred probing

[Sergey Shtylyov]

The driver overrides the error codes returned by platform_get_irq() to
-ENODEV, so if it returns -EPROBE_DEFER, the driver will fail the probe
permanently instead of the deferred probing. Switch to propagating the
error codes upstream...

Fixes: 0d676a6c4390 ("i2c: add support for Socionext SynQuacer I2C controller")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>

---
 drivers/i2c/busses/i2c-synquacer.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/drivers/i2c/busses/i2c-synquacer.c
===================================================================
--- linux.orig/drivers/i2c/busses/i2c-synquacer.c
+++ linux/drivers/i2c/busses/i2c-synquacer.c
@@ -578,7 +578,7 @@ static int synquacer_i2c_probe(struct pl
 
 	i2c->irq = platform_get_irq(pdev, 0);
 	if (i2c->irq < 0)
-		return -ENODEV;
+		return i2c->irq;
 
 	ret = devm_request_irq(&pdev->dev, i2c->irq, synquacer_i2c_isr,
 			       0, dev_name(&pdev->dev), i2c);

Re: [PATCH v2 2/3] i2c: pca-platform: fix deferred probing

[Sergey Shtylyov]

Hello!

On 6/24/21 11:23 PM, Sergey Shtylyov wrote:

> The driver's probe() method chooses the polling mode if an IRQ # returned
> by platform_get_irq_optional() is 0 or  less.  We'll have to filter out
> -EPROBE_DEFER earlier for the deferred probing to work...
> 
> Fixes: 0e8ce93bdceb ("i2c: pca-platform: add devicetree awareness")
> Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> 
> ---
> Changed in version 2:
> - new patch.
> 
>  drivers/i2c/busses/i2c-pca-platform.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Index: linux/drivers/i2c/busses/i2c-pca-platform.c
> ===================================================================
> --- linux.orig/drivers/i2c/busses/i2c-pca-platform.c
> +++ linux/drivers/i2c/busses/i2c-pca-platform.c
> @@ -139,6 +139,8 @@ static int i2c_pca_pf_probe(struct platf
>  	int irq;
>  
>  	irq = platform_get_irq_optional(pdev, 0);
> +	if (irq == -EPROBE_DEFER)
> +		return irq;

   Perhaps we should just use the polling mode? Or is this change still helpful?

>  	/* If irq is 0, we do polling. */
>  	if (irq < 0)
>  		irq = 0;
> 

MBR, Sergei