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From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Stefan Agner <stefan@agner.ch>
Cc: Dmitry Osipenko <digetx@gmail.com>,
	dwmw2@infradead.org, computersforpeace@gmail.com,
	marek.vasut@gmail.com, robh+dt@kernel.org, mark.rutland@arm.com,
	thierry.reding@gmail.com, dev@lynxeye.de,
	miquel.raynal@bootlin.com, richard@nod.at, marcel@ziswiler.com,
	krzk@kernel.org, benjamin.lindqvist@endian.se,
	jonathanh@nvidia.com, pdeschrijver@nvidia.com,
	pgaikwad@nvidia.com, mirza.krak@gmail.com,
	linux-mtd@lists.infradead.org, linux-tegra@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 4/6] mtd: rawnand: add NVIDIA Tegra NAND Flash controller driver
Date: Sat, 9 Jun 2018 08:41:57 +0200	[thread overview]
Message-ID: <20180609084157.0c2f12e6@bbrezillon> (raw)
In-Reply-To: <792ee71847f6f4752b8bcba65d22bf81@agner.ch>

On Sat, 09 Jun 2018 08:23:51 +0200
Stefan Agner <stefan@agner.ch> wrote:

> On 09.06.2018 07:52, Boris Brezillon wrote:
> > On Fri, 08 Jun 2018 23:51:01 +0200
> > Stefan Agner <stefan@agner.ch> wrote:
> > 
> >   
> >> >
> >> > void tegra_nand_controller_reset(struct tegra_nand_controller *ctrl)
> >> > {
> >> > 	int err;
> >> >
> >> > 	disable_irq(ctrl->irq);
> >> >
> >> > 	err = reset_control_reset(ctrl->rst);
> >> > 	if (err) {
> >> > 		dev_err(ctrl->dev, "Failed to reset HW: %d\n", err);
> >> > 		msleep(HW_TIMEOUT);
> >> > 	}
> >> >
> >> > 	writel_relaxed(NAND_CMD_STATUS, ctrl->regs + HWSTATUS_CMD);
> >> > 	writel_relaxed(HWSTATUS_MASK, ctrl->regs + HWSTATUS_MASK);
> >> > 	writel_relaxed(INT_MASK, ctrl->regs + ISR);  
> >>
> >> If we do a controller reset, there is much more state than that which
> >> needs to be restored. A lot of it is not readily available currently
> >> (timing, ECC settings...)  
> > 
> > This is actually a good test to detect what is not properly initialized
> > by the driver. Timings should be configured correctly through  
> > ->setup_data_interface(). ECC engine should be disabled by default and  
> > only enabled when ->{read,write}_page() is called.
> >   
> 
> Is setup_data_interface guaranteed to be called after a failed
> ->exec_op()/{read,write}_page()?

No. Maybe I misunderstood when tegra_nand_controller_reset() was
supposed to be called. That's something I would call only once, early
in the probe function, so that the controller is placed in a well-known
state before we start using it. Definitely not something you should
call after each error.

> 
> >>
> >> That seems a lot of work for a code path I do not intend to ever use :-)
> >>  
> > 
> > Not so sure it's a lot of work. If ECC and timing settings are the
> > only thing you need to initialize then it should work just fine.
> > Try with a controller reset and you'll know if you miss something ;-).  
> 
> Currently the setting gets written directly to the registers. Only the
> enable flag is set in the HW ECC {read,write}_page() functions. So I
> will have to store the complete register in the chip structure and write
> them on every {read,write}_page()?

Well, your solution works as long as you only have one chip connected
to the controller. What we usually set the ECC config in
->select_chip() (or at least make sure the current setting matches the
one we expect) and then enable the engine in read/write_page() (as you
seem to already do).

  reply	other threads:[~2018-06-09  6:42 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-31 22:16 [PATCH v3 0/6] mtd: rawnand: add NVIDIA Tegra NAND flash support Stefan Agner
2018-05-31 22:16 ` [PATCH v3 1/6] mtd: rawnand: add Reed-Solomon error correction algorithm Stefan Agner
2018-06-01  7:26   ` Boris Brezillon
2018-06-01  9:25     ` Boris Brezillon
2018-06-01 13:34       ` Stefan Agner
2018-06-01 13:43         ` Boris Brezillon
2018-05-31 22:16 ` [PATCH v3 2/6] mtd: rawnand: add an option to specify NAND chip as a boot device Stefan Agner
2018-06-01  7:26   ` Boris Brezillon
2018-06-05 20:11   ` Rob Herring
2018-06-06  7:28     ` Boris Brezillon
2018-05-31 22:16 ` [PATCH v3 3/6] mtd: rawnand: tegra: add devicetree binding Stefan Agner
2018-06-01  7:30   ` Boris Brezillon
2018-06-05 20:19     ` Dmitry Osipenko
2018-06-06 10:39       ` Thierry Reding
2018-06-06 10:45         ` Boris Brezillon
2018-06-06 11:07           ` Thierry Reding
2018-06-06 12:14             ` Stefan Agner
2018-06-06 12:31               ` Boris Brezillon
2018-06-05 20:13   ` Rob Herring
2018-05-31 22:16 ` [PATCH v3 4/6] mtd: rawnand: add NVIDIA Tegra NAND Flash controller driver Stefan Agner
2018-06-01  9:20   ` Dmitry Osipenko
2018-06-08 21:51     ` Stefan Agner
2018-06-09  5:52       ` Boris Brezillon
2018-06-09  6:23         ` Stefan Agner
2018-06-09  6:41           ` Boris Brezillon [this message]
2018-06-09  6:46             ` Boris Brezillon
2018-06-09  6:55               ` Boris Brezillon
2018-06-09  6:51             ` Stefan Agner
2018-06-09 12:21       ` Dmitry Osipenko
2018-06-10 11:09         ` Stefan Agner
2018-06-10 15:00           ` Dmitry Osipenko
2018-06-10 15:32             ` Boris Brezillon
2018-06-11 11:45               ` Dmitry Osipenko
2018-06-11 11:50                 ` Boris Brezillon
2018-06-11 13:10                   ` Dmitry Osipenko
2018-06-04 17:16   ` Randolph Maaßen
2018-06-04 20:56     ` Stefan Agner
2018-06-09  5:55   ` Boris Brezillon
2018-06-09  7:18   ` Boris Brezillon
2018-05-31 22:16 ` [PATCH v3 5/6] ARM: dts: tegra: add Tegra20 NAND flash controller node Stefan Agner
2018-05-31 22:16 ` [PATCH v3 6/6] ARM: dts: tegra: enable NAND flash on Colibri T20 Stefan Agner

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