From: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
To: Sebastian Reichel <sre@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>,
mazziesaccount@gmail.com, lee.jones@linaro.org,
robh+dt@kernel.org, mark.rutland@arm.com, lgirdwood@gmail.com,
broonie@kernel.org, gregkh@linuxfoundation.org,
rafael@kernel.org, mturquette@baylibre.com, sboyd@kernel.org,
linus.walleij@linaro.org, bgolaszewski@baylibre.com,
a.zummo@towertech.it, alexandre.belloni@bootlin.com,
wim@linux-watchdog.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
linux-gpio@vger.kernel.org, linux-pm@vger.kernel.org,
linux-rtc@vger.kernel.org, linux-watchdog@vger.kernel.org,
mikko.mutanen@fi.rohmeurope.com,
heikki.haikola@fi.rohmeurope.com
Subject: Re: [RFC PATCH v1 13/13] watchdog: bd70528: Initial support for ROHM BD70528 watchdog block
Date: Thu, 24 Jan 2019 12:44:35 +0200 [thread overview]
Message-ID: <20190124104434.GF2559@localhost.localdomain> (raw)
In-Reply-To: <20190123174728.uu7zhno5xea2bga7@earth.universe>
On Wed, Jan 23, 2019 at 06:47:28PM +0100, Sebastian Reichel wrote:
> Hi,
>
> On Tue, Jan 22, 2019 at 08:03:09PM +0200, Matti Vaittinen wrote:
> > On Tue, Jan 22, 2019 at 09:40:56AM -0800, Guenter Roeck wrote:
> > > On Tue, Jan 22, 2019 at 07:10:23PM +0200, Matti Vaittinen wrote:
> > > > On Tue, Jan 22, 2019 at 07:47:50AM -0800, Guenter Roeck wrote:
> > > > > On Tue, Jan 22, 2019 at 11:48:36AM +0200, Matti Vaittinen wrote:
> > > > > > +static int bd70528_wdt_probe(struct platform_device *pdev)
> > > > > > +{
> > > > > > + struct bd70528 *tmp;
> > > > > > + struct bd70528 *bd70528;
> > > > > > + int ret;
> > > > > > +
> > > > > > + tmp = dev_get_drvdata(pdev->dev.parent);
> > > > > > + if (!tmp) {
> > > > > > + dev_err(&pdev->dev, "No MFD driver data\n");
> > > > > > + return -EINVAL;
> > > > > > + }
> > > > > > + bd70528 = devm_kzalloc(&pdev->dev, sizeof(*bd70528), GFP_KERNEL);
> > > > > > + if (!bd70528)
> > > > > > + return -ENOMEM;
> > > > > > +
> > > > > > + *bd70528 = *tmp;
> > > > > > + bd70528->chip.dev = &pdev->dev;
> > > > >
> > > > > This is wrong.
> > > > > You should not copy the parent's driver data but have local driver
> > > > > data as needed which then points to the parent's driver data if
> > > > > needed. I assume this is why the mutex is a pointer, but that
> > > > > just shows that the whole approach is wrong.
> > > >
> > > > Mutex is a pointer because we want to use same mutex from WDT and RTC.
> > > > We can sure point to parent data but then we still need our own dev
> > > > pointer. So we can have a struct with pointer to parent data and dev
> > > > pointer - but I'm not at all sure it is any clearer.
> > >
> > > As I said, that is wrong. To say it in plaintext, I won't accept
> > > the driver if it copies the parent's driver data. The driver should
> > > have and use its own driver data, and only maintain a pointer to
> > > its parent's driver data. And most definitely you don't want to
> > > copy and use any device data structure from the parent.
> >
> > Allright. At the moment the WDT driver only needs regmap pointer from
> > parent. I'm not sure if it will later need DT or "chip type" - but I
> > will change this.
>
> You probably want to use this:
>
> dev_get_regmap(pdev->dev.parent, NULL);
Thanks a bunch Sebastian. All help is highly appreciated!! =)
Unfortunately I forgot to mention the key thing - the RTC mutex. We also
need that because RTC needs to stop WDT when RTC is adjusted as the WDT
uses RTC as counter - and jumping the RTC WDT enabled might trigger WDT
or have other consequences.
Se even if we used dev_get_regmap (which is slightly heavier than
accessing direct pointer) - we would still need at least the mutex from
parent data, possibly also the chip type and if we want to avoid code
dublication - then also the WDT start/stop function.
Thus I guess we can as well keep the regmap in parent data because we
need the parent data anyways, right?
Br
Matti Vaittinen
--
Matti Vaittinen
ROHM Semiconductors
~~~ "I don't think so," said Rene Descartes. Just then, he vanished ~~~
next prev parent reply other threads:[~2019-01-24 10:44 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-22 9:41 [RFC PATCH v1 00/13] support ROHM BD70528 PMIC Matti Vaittinen
2019-01-22 9:42 ` [RFC PATCH v1 01/13] regmap: regmap-irq: Add main status register support Matti Vaittinen
2019-01-23 15:55 ` Mark Brown
2019-01-22 9:42 ` [RFC PATCH v1 02/13] mfd: bd718x7.h split to ROHM common and bd718x7 specific parts Matti Vaittinen
2019-01-22 9:43 ` [RFC PATCH v1 03/13] regulator: bd718x7 use chip specific and generic data structs Matti Vaittinen
2019-01-23 15:51 ` Mark Brown
2019-01-24 7:16 ` Matti Vaittinen
2019-01-24 10:24 ` Mark Brown
2019-01-22 9:44 ` [RFC PATCH v1 04/13] clk: bd718x7: " Matti Vaittinen
2019-01-22 9:44 ` [RFC PATCH v1 05/13] mfd: bd70528: Support ROHM bd70528 PMIC - core Matti Vaittinen
2019-01-22 14:51 ` Guenter Roeck
2019-01-22 16:20 ` Matti Vaittinen
2019-01-22 9:45 ` [RFC PATCH v1 06/13] clk: bd718x7: Support ROHM BD70528 clk block Matti Vaittinen
2019-01-22 9:45 ` [RFC PATCH v1 07/13] devicetree: bindings: Document first ROHM BD70528 bindings Matti Vaittinen
2019-02-23 0:30 ` Rob Herring
2019-02-28 6:49 ` Matti Vaittinen
2019-02-28 15:37 ` Rob Herring
2019-01-22 9:46 ` [RFC PATCH v1 08/13] regulator: bd70528: Support ROHM BD70528 regulator block Matti Vaittinen
2019-01-22 9:46 ` [RFC PATCH v1 09/13] devicetree: bindings: ROHM bd70528 regulator bindings Matti Vaittinen
2019-01-22 9:47 ` [RFC PATCH v1 10/13] gpio: Initial support for ROHM bd70528 GPIO block Matti Vaittinen
2019-01-22 9:47 ` [RFC PATCH v1 11/13] rtc: bd70528: Initial support for ROHM bd70528 RTC Matti Vaittinen
2019-01-22 14:48 ` Guenter Roeck
2019-01-22 16:29 ` Matti Vaittinen
2019-01-22 9:48 ` [RFC PATCH v1 12/13] power: supply: Initial support for ROHM BD70528 PMIC charger block Matti Vaittinen
2019-01-22 9:48 ` [RFC PATCH v1 13/13] watchdog: bd70528: Initial support for ROHM BD70528 watchdog block Matti Vaittinen
2019-01-22 15:47 ` Guenter Roeck
2019-01-22 17:10 ` Matti Vaittinen
2019-01-22 17:40 ` Guenter Roeck
2019-01-22 18:03 ` Matti Vaittinen
2019-01-23 17:47 ` Sebastian Reichel
2019-01-24 10:44 ` Matti Vaittinen [this message]
2019-01-24 14:37 ` Guenter Roeck
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