From mboxrd@z Thu Jan  1 00:00:00 1970
From: Scott Wood <scottwood@freescale.com>
Date: Thu, 16 Jul 2015 16:36:08 -0500
Subject: [U-Boot] [PATCH 1/4] sunxi: nand: Add basic sunxi NAND driver
 with DMA support
In-Reply-To: <201507162326.51716.marex@denx.de>
References: <1437045915-25755-1-git-send-email-pzierhoffer@antmicro.com>
 <1437045915-25755-2-git-send-email-pzierhoffer@antmicro.com>
 <1437081358.2993.156.camel@freescale.com>
 <201507162326.51716.marex@denx.de>
Message-ID: <1437082568.2993.166.camel@freescale.com>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

On Thu, 2015-07-16 at 23:26 +0200, Marek Vasut wrote:
> On Thursday, July 16, 2015 at 11:15:58 PM, Scott Wood wrote:
> 
> [...]
> 
> > > +/* temporary buffer in internal ram */
> > > +#ifdef CONFIG_SPL_BUILD
> > > +/* in SPL temporary buffer cannot be @ 0x0 */
> > > +unsigned char temp_buf[SPL_WRITE_SIZE] __aligned(0x10)
> > > __section(".text#"); +#else
> > > +/* put temporary buffer @ 0x0 */
> > > +unsigned char *temp_buf = (unsigned char *)0x0;
> > > +#endif
> > 
> > If 0x0 is the address of an SRAM, its address should be symbolically
> > defined. Also consider mapping it to a different virtual address, to avoid
> > potential compiler mischief.
> 
> The DMA I believe accesses it via PA anyway, so mapping it elsewhere would
> only confuse everyone who's hacking on the driver. Just my 5 cents ;-)

Hey, if it wakes people up to the fact that they ought to be using 
virt_to_phys() (or better yet, something that distinguishes DMA addresses 
from physical), great! :-)

And yes, people go on to do the same "everything is u32" crap in non-platform-
specific files.  Just look at drivers/block/ahci.c.

-Scott