[PATCH0/2] Fix deferred probing in the I2C bus drivers

[PATCH0/2] Fix deferred probing in the I2C bus drivers

[Sergey Shtylyov]

Here are 2 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.

[1/2] i2c: iop3xx: fix deferred probing
[2/2] i2c: synquacer: fix deferred probing

[PATCH 1/2] i2c: iop3xx: fix deferred probing

[Sergey Shtylyov]

When adding the code to handle platform_get_irq*() errors in 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@omprussia.ru>

---
 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 2/2] 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: [PATCH0/2] Fix deferred probing in the I2C bus drivers

[Sergey Shtylyov]

Hello~

On 4/17/21 11:57 PM, Sergey Shtylyov wrote:

> Here are 2 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.
> 
> [1/2] i2c: iop3xx: fix deferred probing
> [2/2] i2c: synquacer: fix deferred probing

   Please hold on with this series; I'm gonna add another patch...

MBR, Sergey

Re: [PATCH0/2] Fix deferred probing in the I2C bus drivers

[Sergey Shtylyov]

On 5/28/21 11:57 PM, Sergey Shtylyov wrote:

[...]
>> Here are 2 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.
>>
>> [1/2] i2c: iop3xx: fix deferred probing
>> [2/2] i2c: synquacer: fix deferred probing
> 
>    Please hold on with this series; I'm gonna add another patch...

   Actually, I'm unsure about drivers/i2c/busses/i2c-pca-platform.c: normally it
uses polling iff the (considered optional) IRQ can't be set up (irq < 0 returned
from platform_get_irq_optional()) then polling mode is used. I have a patch to
propaate -EPROBE_DEFER upstream but I'm not sure what is better : sefer the probe
(and potentially falling permanently iff the kernel wouldn't able to finally set
up the IRQ or to start the I2C driver in the polling mode right away. Does these
doubts even make sense? :-)

MBR, Sergey

Re: [PATCH0/2] Fix deferred probing in the I2C bus drivers

[Sergey Shtylyov]

On 5/30/21 6:53 PM, Sergey Shtylyov wrote:

[...]
>>> Here are 2 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.
>>>
>>> [1/2] i2c: iop3xx: fix deferred probing
>>> [2/2] i2c: synquacer: fix deferred probing
>>
>>    Please hold on with this series; I'm gonna add another patch...
> 
>    Actually, I'm unsure about drivers/i2c/busses/i2c-pca-platform.c: normally it
> uses polling iff the (considered optional) IRQ can't be set up (irq < 0 returned
> from platform_get_irq_optional()) then polling mode is used.

   I started to be tautologcial, should really re-read the msgs before seding... :-)

> I have a patch to
> propaate -EPROBE_DEFER upstream but I'm not sure what is better : sefer the probe

   Propagate, of/c. :-)

> (and potentially falling permanently iff the kernel wouldn't able to finally set

   Wasn't. :-)

> up the IRQ or to start the I2C driver in the polling mode right away. Does these
> doubts even make sense? :-)

MBR, Sergey