On Wed, Aug 04, 2010 at 10:24:50AM +0200, Guennadi Liakhovetski wrote: > On Wed, 4 Aug 2010, Sascha Hauer wrote: > > > On Wed, Aug 04, 2010 at 01:01:34AM +0200, Guennadi Liakhovetski wrote: > > > On Tue, 3 Aug 2010, Michael Grzeschik wrote: > > > > > > > On Tue, Aug 03, 2010 at 08:22:13PM +0200, Guennadi Liakhovetski wrote: > > > > > On Tue, 3 Aug 2010, Michael Grzeschik wrote: > > > > > > > > > > > change this driver back to register and probe, since some platforms > > > > > > first have to initialize an already registered power regulator to switch > > > > > > on the camera. > > > > > > > > > > Sorry, don't see a difference. Can you give an example of two call > > > > > sequences, where this change changes the behaviour? > > > > > > > > > > > > > Yes, when you look at the today posted patch [1] you find the function > > > > pcm970_baseboard_init_late as an late_initcall. It uses an already > > > > registred regulator device to turn on the power of the camera before the > > > > cameras device registration. > > > > > > > > [1] [PATCH 1/2] ARM: i.MX27 pcm970: Add camera support > > > > http://lists.infradead.org/pipermail/linux-arm-kernel/2010-August/022317.html > > > > > > Sorry again, still don't understand. What I mean is the following: take > > > two cases - before and after your patch. What is the difference? As far as > > > I know, the difference between platform_driver_probe() and > > > platform_driver_register() is just that the probe method gets discarded in > > > an __init section, which is suitable for non hotpluggable devices. I don't > > > know what the difference this should make for call order. So, that's what > > > I am asking about. Can you explain, how this patch changes the call order > > > in your case? Can you tell, that in the unpatches case the probe is called > > > at that moment, and in the patched case it is called at a different point > > > of time and that fixes the problem. > > > > > > The following is above platform_driver_probe: > > > > * Use this instead of platform_driver_register() when you know the device > > * is not hotpluggable and has already been registered, and you want to > > * remove its run-once probe() infrastructure from memory after the > > * driver has bound to the device. > > > > So platform_driver_probe will only call the probe function when the device > > is already there when this function runs. This is not the case on our board. > > We have to register the camera in late_initcall (to make sure the needed > > regulators are already there). During late_initcall time the > > platform_driver_probe has already run. > > Ok, now I see. I missed the key-phrase: "before the cameras device > registration." Ok, in this case, it's certainly a valid reason for the > change. Just one more question: wouldn't calling > pcm970_baseboard_init_late() from device_initcall fix the problem without > requiring to change the driver? No, sorry but this doesn't solve the problem. I tested it and get an "unable to get regulator: -19" when i hit on that. The problem is the device init order. The pcm970_baseboard_init_late comes first and then the regulator. So i think we should keep that patch. Michael -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
