linux-kernel - Re: [PATCH 2/2] mtd/maps: uclinux: support Blackfin systems

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Message-ID: <20090526170653.GB24261@linux-sh.org>
Date:	Wed, 27 May 2009 02:06:54 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	Mike Frysinger <vapier.adi@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	Greg Ungerer <gerg@...inux.org>, uclinux-dev@...inux.org,
	linux-mtd@...ts.infradead.org
Subject: Re: [PATCH 2/2] mtd/maps: uclinux: support Blackfin systems

On Tue, May 26, 2009 at 12:50:51PM -0400, Mike Frysinger wrote:
> On Tue, May 26, 2009 at 12:47, Paul Mundt wrote:
> > On Tue, May 26, 2009 at 12:42:48PM -0400, Mike Frysinger wrote:
> >> > In this case you should just kill all of that crap off, and have the
> >> > platforms that use this set uclinux_ram_map up themselves, it's already
> >> > a global. Of course you can use _ebss as a default value for
> >> > uclinux_ram_map.phys and just override it in your platform.
> >>
> >> i would agree if it were a board-specific issue, but it's an arch
> >> issue, so pushing it to the boards level is wrong. ??i can however
> >> replace the addr with a global weak and add a symbol into the Blackfin
> >> arch code to override it.
> >>
> > I obviously meant architectures setting up the address, not the board
> > code, as this has nothing at all to do with boards. There are already
> > plenty of cases in setup_arch() for filling in uclinux mtd data, one more
> > isn't going to make a difference.
> >
> > I don't see anything wrong with keeping uclinux_ram_map as a global
> > however, particularly since platforms that need to special case the
> > mapping can easily do this under the existing ifdef. Adding weak symbols
> > for something like this just seems silly.
> 
> the point of the weak symbol was so that the map could provide a sane
> default that works for most everyone out there without having to copy
> & paste the same code to every arch, and to make new arch porters
> worry about what needs to be done to use this very trivial map

Did you purposely only read the parts of my email that you felt like?
Note the original quoted part that mentions using _ebss as a default and
simply overriding it in your platform.

Use the attached, and then just set uclinux_ram_map.phys = your_address_here
in your setup_arch(). Having weak symbols in drivers that are supposed to
be overriden by the architecture code is just way too backwards for
words. Globals suffice fine for this sort of thing, if you are not going
to go to the effort to pass this information to the driver directly that
is.

---

diff --git a/drivers/mtd/maps/uclinux.c b/drivers/mtd/maps/uclinux.c
index 81756e3..12f822d 100644
--- a/drivers/mtd/maps/uclinux.c
+++ b/drivers/mtd/maps/uclinux.c
@@ -22,8 +22,11 @@
 
 /****************************************************************************/
 
+extern char _ebss;
+
 struct map_info uclinux_ram_map = {
 	.name = "RAM",
+	.phys = (unsigned long)&_ebss,
 };
 
 struct mtd_info *uclinux_ram_mtdinfo;
@@ -55,12 +58,9 @@ static int __init uclinux_mtd_init(void)
 {
 	struct mtd_info *mtd;
 	struct map_info *mapp;
-	extern char _ebss;
-	unsigned long addr = (unsigned long) &_ebss;
 
 	mapp = &uclinux_ram_map;
-	mapp->phys = addr;
-	mapp->size = PAGE_ALIGN(ntohl(*((unsigned long *)(addr + 8))));
+	mapp->size = PAGE_ALIGN(ntohl(*((unsigned long *)(mapp->phys + 8))));
 	mapp->bankwidth = 4;
 
 	printk("uclinux[mtd]: RAM probe address=0x%x size=0x%x\n",
--
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