linux-kernel - RE: [PATCH] usb: dwc3: core: modify IO memory resource after deferred probe completes

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Message-ID: <A2CA0424C0A6F04399FB9E1CD98E030458DE178C@US01WEMBX2.internal.synopsys.com>
Date:	Fri, 26 Jul 2013 18:44:23 +0000
From:	Paul Zimmerman <Paul.Zimmerman@...opsys.com>
To:	"balbi@...com" <balbi@...com>,
	"Ivan T. Ivanov" <iivanov@...sol.com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] usb: dwc3: core: modify IO memory resource after
 deferred probe completes

> From: Felipe Balbi [mailto:balbi@...com]
> Sent: Friday, July 26, 2013 2:54 AM
> > > > Also, this is not *modifying* what was passed, just skipping the xHCI
> > > > address space so we don't request_mem_region() an area we won't really
> > > > handle and prevent xhci-hcd.ko from probing.
> > >
> > > Hmm? platform_get_resource() returns a pointer to an entry in the
> > > platform_device's resource[] array. And "res->start +=" modifies the
> > > entry pointed at. If it didn't, the bug fixed by this patch wouldn't
> > > have happened.
> > >
> > > Are you sure this code will work OK if you build the driver as a module,
> > > modprobe it, rmmod it, and then modprobe it again? Seems like it won't,
> > > unless the dev->resource[] array gets reinitialized in between somehow.
> 
> gotta try that one... Perhaps the correct way would be to copy the
> resource to a private struct resource and modify that one, leaving
> pdev->resources untouched.

Maybe this is a dumb question, but why can't the driver that is going
to use the resource after this just "know" that it has to add
DWC3_GLOBALS_REGS_START to the start address? Are there some versions
of the core where that is not the case?

Or, maybe there should be two sets of resources?

-- 
Paul

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