Re: patch bus_add_device-losing-an-error-return-from-the-probe-method.patch added to gregkh-2.6 tree

[Rene Herman <rene.herman@keyaccess.nl>]

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Dmitry Torokhov wrote:

> You need to let go of the model that driver that drives hardware also
> do the device discovery and it will all fall into place.

It's not possible to sanely let go of that model. ISA discovery involves 
(as an example) poking at the same I/O ports as using does, meaning you 
will have to share a request_region() over discovery and use for one -- 
you can't decouple that due to obvious races.

>> Anyways, the additional method would, I feel, be the conceptually
>> cleanest approach. Practically speaking though, simply doing a manual
>> probe and only calling platform_register() after everything is found to
>> be present and accounted for is not much of a problem either.
>>
> 
> Unfortunately it breaks manual driver binding/unbinding through sysfs
> so I don't think it is a good long-term solution.

Yes. I don't see a significantly cleaner solution then than the slightly 
hackish "using drvdata as a private success flag" that I posted before. 
Example patch versus snd_adlib attached again. This seems to work well.

Takashi: do you agree? If the probe() method return is not going to be 
propagated up, there are few other options.

(Continuing the loop on IS_ERR(device) is then also a bit questionable 
again as the IS_ERR then signifies an eror in the bowels of the device 
model, but I feel it's still the correct thing to do)

Rene.


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Index: local/sound/isa/adlib.c
===================================================================
--- local.orig/sound/isa/adlib.c	2006-04-05 02:00:55.000000000 +0200
+++ local/sound/isa/adlib.c	2006-04-05 02:05:45.000000000 +0200
@@ -43,8 +43,7 @@ static int __devinit snd_adlib_probe(str
 	struct snd_card *card;
 	struct snd_opl3 *opl3;
 
-	int error;
-	int i = device->id;
+	int error, i = device->id;
 
 	if (port[i] == SNDRV_AUTO_PORT) {
 		snd_printk(KERN_ERR DRV_NAME ": please specify port\n");
@@ -95,8 +94,7 @@ static int __devinit snd_adlib_probe(str
 	return 0;
 
 out1:	snd_card_free(card);
- out0:	error = -EINVAL; /* FIXME: should be the original error code */
-	return error;
+out0:	return error;
 }
 
 static int __devexit snd_adlib_remove(struct platform_device *device)
@@ -134,6 +132,11 @@ static int __init alsa_card_adlib_init(v
 		if (IS_ERR(device))
 			continue;
 
+		if (!platform_get_drvdata(device)) {
+			platform_device_unregister(device);
+			continue;
+		}
+
 		devices[i] = device;
 		cards++;
 	}