Message-ID: <20150302224415.GB25163@verge.net.au>
Date:	Tue, 3 Mar 2015 07:44:16 +0900
From:	Simon Horman <horms@...ge.net.au>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Wolfram Sang <wsa@...-dreams.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>,
	Support Opensource <support.opensource@...semi.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [RFC] ARM: shmobile: R-Car Gen2: Add da9063/da9210
 regulator quirk

On Mon, Mar 02, 2015 at 09:49:11PM +0100, Geert Uytterhoeven wrote:
> Hi Wolfram,
> 
> On Mon, Mar 2, 2015 at 7:32 PM, Wolfram Sang <wsa@...-dreams.de> wrote:
> > On Mon, Mar 02, 2015 at 06:28:43PM +0100, Geert Uytterhoeven wrote:
> >> The r8a7791/koelsch development board has da9063 and da9210 regulators.
> >> Both regulators have their interrupt request lines tied to the same
> >> interrupt pin (IRQ2) on the SoC.
> >>
> >> After boot-up, both the da9063 and da9210 seem to assert their interrupt
> >> request lines.  Hence as soon as one driver requests this irq, it gets
> >> stuck in an interrupt storm, as it only manages to deassert its own
> >> interrupt request line, and the other driver hasn't installed an
> >> interrupt handler yet.
> >>
> >> To handle this, install a quirk that masks the interrupts in both the
> >> da9063 and da9210.  This quirk has to run after the i2c master driver
> >> has been initialized, but before the i2c slave drivers are initialized.
> >>
> >> On koelsch, the following happens:
> >>
> >>   - Cold boot or reboot using the da9063 restart handler:
> >>
> >>       IRQ2 is asserted, installing da9063/da9210 regulator quirk
> >>       ...
> >>       i2c i2c-6: regulator_quirk_notify: 1, IRQC_MONITOR = 0x3fb
> >>       i2c 6-0058: regulator_quirk_notify: 1, IRQC_MONITOR = 0x3fb
> >>       i2c 6-0058: Detected da9063
> >>       i2c 6-0058: Masking da9063 interrupt sources
> >>       i2c 6-0068: regulator_quirk_notify: 1, IRQC_MONITOR = 0x3fb
> >>       i2c 6-0068: Detected da9210
> >>       i2c 6-0068: Masking da9210 interrupt sources
> >>       i2c 6-0068: IRQ2 is not asserted, removing quirk
> >>
> >>   - Warm boot (reset button):
> >>
> >>       rcar_gen2_regulator_quirk: IRQ2 is not asserted, not installing quirk
> >>
> >> Not-yet-signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> >> ---
> >> Based on the schematics, I believe r8a7790/lager is also affected.
> >
> > Boot log from Lager (cold boot & watchdog reboot):
> >
> > [    0.117037] IRQ2 is asserted, installing da9063/da9210 regulator quirk
> > [    0.162803] i2c i2c-4: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.163050] i2c-sh_mobile e6500000.i2c: I2C adapter 4, bus speed 100000 Hz
> > [    0.164283] i2c i2c-5: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.164481] i2c-sh_mobile e6510000.i2c: I2C adapter 5, bus speed 100000 Hz
> > [    0.165836] i2c i2c-6: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.166352] i2c 6-0012: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.166425] i2c 6-0012: Detected ak4643
> > [    0.166891] i2c 6-0020: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.166963] i2c 6-0020: Detected adv7180
> > [    0.167421] i2c 6-0039: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.167494] i2c 6-0039: Detected adv7511w
> > [    0.167630] i2c-sh_mobile e6520000.i2c: I2C adapter 6, bus speed 100000 Hz
> > [    0.168805] i2c i2c-7: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.169343] i2c 7-0058: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.169415] i2c 7-0058: Detected da9063
> > [    0.169479] i2c 7-0058: Masking da9063 interrupt sources
> > [    0.175641] i2c 7-0068: regulator_quirk_notify: 1, IRQC_MONITOR = 0xb
> > [    0.175715] i2c 7-0068: Detected da9210
> > [    0.175778] i2c 7-0068: Masking da9210 interrupt sources
> > [    0.176757] i2c 7-0068: IRQ2 is not asserted, removing quirk
> >
> > Reboot using reset:
> >
> > [    0.117819] rcar_gen2_regulator_quirk: IRQ2 is not asserted, not installing quirk
> >
> > So, not surprisingly, no difference to Koelsch. For completeness, I disabled
> > installing the notifier and got the interrupt storm again. So:
> >
> > Tested-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> 
> Thanks for testing!
> 
> >> +#ifdef CONFIG_I2C
> >
> > Is it a realistic scenario that I2C and slave drivers are modules?
> 
> Yes.
> 
> Unfortunately that's more difficult to support, as the code references
> i2c_bus_type and i2c_adapter_type.
> 
> i2c_bus_type is needed to register the notifier.
> i2c_adapter_type is needed to distinguish between i2c adapters and clients,
> as the notifier is called for both with action BUS_NOTIFY_ADD_DEVICE.
> 
> >> +static int regulator_quirk_notify(struct notifier_block *nb,
> >> +                               unsigned long action, void *data);
> >
> > This forward declaration can be skipped...
> >
> >> +
> >> +static struct notifier_block regulator_quirk_nb = {
> >> +     .notifier_call = regulator_quirk_notify
> >> +};
> >
> > ... if you move this after the notfier function.
> 
> regulator_quirk_nb and regulator_quirk_notify reference each other.
> But regulator_quirk_notify() can probably just use the passed
> struct notifier_block pointer. Will fix.
> 
> > Other than that the code looks okay to me (given that this is a quirk
> > workaround).

Hi Geert,

this seems reasonable enough to me, however, I'd like to let it hang out
for a bit longer to see if there is any further review. To that end could
you consider posting a non-RFC version for review if you wish to pursue
this approach further?
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