[U-Boot] [PATCH v3] arm: socfpga: fix issue with warm reset when CSEL is 0

[Dalon Westergreen <dwesterg@gmail.com>]

On Sun, 2017-03-05 at 18:49 +0100, Marek Vasut wrote:
> On 03/05/2017 06:38 PM, Dalon Westergreen wrote:
> > 
> > On Tue, 2017-02-28 at 06:45 -0800, Dalon Westergreen wrote:
> > > 
> > > On Mon, 2017-02-20 at 06:35 -0800, Dalon Westergreen wrote:
> > > > 
> > > > 
> > > > On Mon, 2017-02-20 at 15:24 +0100, Marek Vasut wrote:
> > > > > 
> > > > > 
> > > > > 
> > > > > On 02/20/2017 03:21 PM, Dalon Westergreen wrote:
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > On Mon, 2017-02-20 at 15:14 +0100, Marek Vasut wrote:
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > On 02/20/2017 03:10 PM, Dalon Westergreen wrote:
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > On Mon, 2017-02-20 at 10:07 +0100, Marek Vasut wrote:
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > On 02/18/2017 02:34 AM, Dalon Westergreen wrote:
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > When CSEL=0x0 the socfpga bootrom does not touch the clock
> > > > > > > > > > configuration for the device.  This can lead to a boot
> > > > > > > > > > failure
> > > > > > > > > > on warm resets. This patch disables warm resets when CSEL=0.
> > > > > > > > > > This results in the clock and pll configurations being reset
> > > > > > > > > > on any reset issued when CSEL=0.
> > > > > > > > > > 
> > > > > > > > > > Signed-off-by: Dalon Westergreen <dwesterg@gmail.com>
> > > > > > > > > 
> > > > > > > > > What about my suggestion for V2 about just loading function
> > > > > > > > > pointer
> > > > > > > > > into
> > > > > > > > > the reset jump address register ?
> > > > > > > > 
> > > > > > > > Frankly, i really dont like relying on the existence of a
> > > > > > > > snippet of
> > > > > > > > code in
> > > > > > > > the
> > > > > > > > onchip ram being untouched to ensure a reboot/reset will occur
> > > > > > > > for
> > > > > > > > this
> > > > > > > > csel=0
> > > > > > > > case.  i am certain this case is rarely used, and confident that
> > > > > > > > it
> > > > > > > > isnt
> > > > > > > > being
> > > > > > > > used while trying to preserve sdram contents.
> > > > > > > 
> > > > > > > Well, you already rely on such snippet, it's SPL. If you corrupt
> > > > > > > SPL
> > > > > > > and
> > > > > > > do warm reset, your system hangs, I had that multiple times :)
> > > > > > 
> > > > > > True.  I would argue to just use cold resets but i think arria 10
> > > > > > has
> > > > > > more
> > > > > > use
> > > > > > for the warm reset case.
> > > > > 
> > > > > OK
> > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > the downside is that the scorecard is reset every boot. so the
> > > > > > > > bootrom
> > > > > > > > will
> > > > > > > > retry all the spl images again resulting in possibly longer boot
> > > > > > > > times.
> > > > > > > 
> > > > > > > Is that significant ?
> > > > > > 
> > > > > > The watchdog timeout is on the order of 1.5 seconds.  That would be
> > > > > > for
> > > > > > each
> > > > > > failed spl.
> > > > > 
> > > > > Hm, OK. But then your system is kinda broken, so you should expect
> > > > > this
> > > > > I guess.
> > > > 
> > > > My thought exactly...  I would like to see if Chin Liang or Dinh have
> > > > any
> > > > comments?
> > > 
> > > Chin Liang, Dinh, any comments?
> > 
> > Marek, I would like to propose we move forward with this patch?
> 
> TBH I'm still thinking if you turned the V2 into C code and passed a 
> function pointer into the warm reset jump address register, that'd be 
> the best.
> 
I will give it a shot, i just dont like relying on the spl image still
being present in the onchip ram.  There is nothing preventing an errant
process or user from overwriting it and i have run into customers using
that memory for their own purposes.

-dalon

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