linux-kernel - Re: [PATCH] mtd: bcm47xxsflash: use devm_ioremap

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Message-ID: <20160108185120.GQ109450@google.com>
Date:	Fri, 8 Jan 2016 10:51:20 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Rafał Miłecki <zajec5@...il.com>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Luis de Bethencourt <luisbg@....samsung.com>,
	Jeremy Kerr <jk@...abs.org>,
	Neelesh Gupta <neelegup@...ux.vnet.ibm.com>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Cyril Bur <cyrilbur@...il.com>
Subject: Re: [PATCH] mtd: bcm47xxsflash: use devm_ioremap_nocache() instead
 of KSEG0ADDR()

On Fri, Jan 08, 2016 at 02:01:00PM +0000, Maciej W. Rozycki wrote:
> On Fri, 8 Jan 2016, Rafał Miłecki wrote:
> 
> > > This removes some (implicit) MIPS dependencies and makes the code more
> > > portable, whether we need it or not :)
> > 
> > So now we have following forwardtrace:
> > devm_ioremap_nocache
> > ioremap_nocache
> > __ioremap_mode
> > __ioremap
> > CKSEG1ADDR

I just noticed that ioremap() and ioremap_nocache() are the same on
MIPS. So I could just do devm_ioremap_resource() and save myself a few
lines...

> > It results in different address than KSEG0ADDR:
> > [    1.339752] [bcm47xxsflash_bcma_probe] KSEG0ADDR(BCMA_SOC_FLASH2):9c000000
> > [    1.346848] [bcm47xxsflash_bcma_probe] devm_ioremap_nocache:bc000000
> > 
> > But it still works as expected! :)
> > [    1.609426] 6 bcm47xxpart partitions found on MTD device bcm47xxsflash
> > [    1.616169] Creating 6 MTD partitions on "bcm47xxsflash":
> 
>  It is a functional change though and I think the change from a cached to 
> uncached mapping (i.e. from `ioremap' to `ioremap_nocache') has to be a 
> separate patch, so that both changes can be reviewed independently.

As I noted before sending my patch, I don't think this driver should
have been using KSEG0 anyway; it should have been KSEG1, right? I can
note that in the patch description, but I don't really see why it needs
to be a separate patch.

Brian