Re: [PATCH] mtd: rawnand: fsmc: Keep CE enabled fix mb() drain

[Boris Brezillon <bbrezillon@xxxxxxxxxx>]

On Wed, 9 Jan 2019 22:21:25 +0100
Boris Brezillon <bbrezillon@xxxxxxxxxx> wrote:

> On Wed,  9 Jan 2019 21:55:30 +0100
> Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> 
> > Hammering the chip enable on and off between every command
> > crashes the Nomadik NHK15 with this message:
> > 
> > Scanning device for bad blocks
> > Unhandled fault: external abort on non-linefetch (0x008) at 0xcc95e000
> > pgd = (ptrval)
> > [cc95e000] *pgd=0b808811, *pte=40000653, *ppte=40000552
> > Internal error: : 8 [#1] PREEMPT ARM
> > Modules linked in:
> > CPU: 0 PID: 1 Comm: swapper Not tainted 4.20.0-rc2+ #72
> > Hardware name: Nomadik STn8815
> > PC is at fsmc_exec_op+0x194/0x204
> > (...)
> > 
> > This patch keeps the CE (chip enable, the only chip select)
> > signal from the FSMC block enabled from the first command
> > after probe() or resume() until the driver either suspend()
> > or remove(). Create a state variable to track this.  
> 
> I just read the Spear600 reference manual, and I'm not sure the
> BANK_ENABLE bit controls the CE line. My understanding is that it just
> marks the bank as active and CE line is asserted when you actually
> access the AHB mem bank range (probably after making sure the FSMC bus
> is idle).

My bad, I was looking at the CTRL reg, not CTRL_PC.

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