[U-Boot] [PATCH 2/9] rockchip: support 4GB DRAM on 32bit systems

[Carlo Caione]

On Fri, 2018-07-27 at 00:54 +0200, Dr. Philipp Tomsich wrote:
> > On 26 Jul 2018, at 22:05, Carlo Caione <carlo at endlessm.com> wrote:
> > 
> > On Thu, 2018-07-26 at 15:59 +0200, Philipp Tomsich wrote:
> > > The calculation in `rockchip_sdram_size` would overflow for 4GB
> > > on
> > > 32bit systems (i.e. when PHYS_64BIT is not defined).
> > > 
> > > This makes the internal variables and the signature prototype use
> > > a
> > > u64 to ensure that we can represent the 33rd bit (as in '4GB').
> > > 
> > 
> > Hi Philipp,
> > just to let you know that this is still not working on the veyron
> > jerry
> > chromebook with 4GB I have here (RK3288). The boot stops at:
> > 
> > U-Boot SPL 2018.07-00403-gdbe6ef8276 (Jul 26 2018 - 17:21:11 +0100)
> > Trying to boot from SPI
> > 
> > U-Boot 2018.07-00403-gdbe6ef8276 (Jul 26 2018 - 17:21:11 +0100)
> > 
> > Model: Google Jerry
> > DRAM:  0 Bytes
> > 
> > I'm still investigating why but for sure there are several points
> > to
> > fix to have a proper debug, see [0].
> 
> I reread ‘rockchip_sdram_size’ and it looks as if I forgot to mark
> the value
> shifted to create chipsize_mb as ULL.  When looking at this code I
> had an
> uneasy feeling that this might run into the C type rules (i.e. 1 will
> be a 32bit
> integer and shifting it by 32 would result in 0), but I didn’t think
> that this
> would ever be the case and that any 4GB DRAM setup would be made
> up of multiple channels or of multiple ranks.

It doesn't hurt but rockchip_sdram_size() is returning the correct
value of 0x100000000 in my tests.

-- 
Carlo Caione <carlo.caione at gmail.com>