From: Boris Brezillon <bbrezillon@kernel.org>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
Marek Vasut <marek.vasut@gmail.com>,
Richard Weinberger <richard@nod.at>,
linux-mtd@lists.infradead.org
Subject: Re: [PATCH] mtd: rawnand: fsmc: Keep CE enabled fix mb() drain
Date: Wed, 9 Jan 2019 23:05:25 +0100 [thread overview]
Message-ID: <20190109230525.62038898@bbrezillon> (raw)
In-Reply-To: <CACRpkdaouj-0gC4p1Ymx+guxDLO7R0FzQZncgNQjaHkGuiAhLQ@mail.gmail.com>
On Wed, 9 Jan 2019 22:40:22 +0100
Linus Walleij <linus.walleij@linaro.org> wrote:
> On Wed, Jan 9, 2019 at 10:21 PM Boris Brezillon <bbrezillon@kernel.org> wrote:
> > On Wed, 9 Jan 2019 21:55:30 +0100
> > Linus Walleij <linus.walleij@linaro.org> wrote:
>
> > > 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).
>
> The Nomadik STn8815 says (for this bit):
>
> PBKEN PC-card/NAND-Flash chip-select enable.
> Enables the corresponding chip-select.
> If a disabled chip-select is accessed, an HRESP = ERROR is generated
> on the AHB bus.
> 0: disabled (default after reset)
> 1: enabled
>
> The same for Nomadik STn8820 and the Ux500 variants.
>
> So "enable" might very well have the meaning you say above,
> it's just very unclear and confusing.
>
> > If I'm correct, I'd recommend dropping fsmc_ce_ctrl() and marking the
> > bank enabled at probe time.
>
> This already happens in fsmc_nand_setup() so we just
> need to delete some code then.
>
> But maybe we should disable it during remove()
> at least?
Yep, and set it again at resume time, just in case regs content is lost
at suspend time.
next prev parent reply other threads:[~2019-01-09 22:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-09 20:55 [PATCH] mtd: rawnand: fsmc: Keep CE enabled fix mb() drain Linus Walleij
2019-01-09 21:21 ` Boris Brezillon
2019-01-09 21:40 ` Linus Walleij
2019-01-09 22:05 ` Boris Brezillon [this message]
2019-01-09 21:49 ` Boris Brezillon
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