linux-kernel - Re: [PATCH V3 4/8] phy: Initialize phy core with subsys

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Message-ID: <20140131034803.GA2618@pratyush-vbox>
Date:	Fri, 31 Jan 2014 09:18:03 +0530
From:	Pratyush Anand <pratyush.anand@...com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Kishon Vijay Abraham I <kishon@...com>,
	Mohit KUMAR DCG <Mohit.KUMAR@...com>,
	spear-devel <spear-devel@...t.st.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH V3 4/8] phy: Initialize phy core with subsys_initcall

On Thu, Jan 30, 2014 at 08:44:58PM +0800, Arnd Bergmann wrote:
> On Thursday 30 January 2014, Pratyush Anand wrote:
> > On Thu, Jan 30, 2014 at 07:43:37PM +0800, Kishon Vijay Abraham I wrote:
> > > Hi,
> > > 
> > > On Thursday 30 January 2014 04:18 PM, Mohit Kumar wrote:
> > > > From: Pratyush Anand <pratyush.anand@...com>
> > > > 
> > > > PCIe RC drivers are initialized with subsys_initcall. Few PCIe drivers
> > > > like SPEAr13xx needs phy drivers to be initialized.
> > > 
> > > Instead change PCIe RC drivers to module init. Phy drivers should be loaded
> > > very early otherwise. (Hint: drivers/Makefile).
> > 
> > I think PCIe RC driver can not be made module init. Bjorn can comment
> > better.
> 
> I don't think there is any problem here: the PCI devices will only appear
> after the PCIe root bus has been probed. All drivers using the regular
> pci_driver framework should work fine even if they are loaded before the
> device is found. There are a handful of drivers using 'pci_get_device'
> rather than pci_register_driver, and those will break. As far as I can
> tell, those drivers are all x86 specific, and you should not worry about
> them.
> 
> Having the PHY driver get initialized after the PCI root driver should
> also work, but it requires correct handling of -EPROBE_DEFER: if phy_get

I had issue with phy-core driver getting initialized after pcie rc
driver. I found a kernel crash, as devm_phy_get was called before
phy_class was created. I think this too need to be fixed, we should
not see a crash.

Anyway, I will keep spear phy and rc driver both with module_init and
-EPROBE_DEFER implementation.

Regards
Pratyush
> returns this error, the PCI driver must silently return the same error
> from its probe() function so it will get called again at a later time
> (after some other devices have been probed successfully).
> 
> 	Arnd
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