linux-kernel - Re: [PATCH-v6 5/6] mfd: 88pm800: Set default interrupt clear method

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Message-ID: <20150824155129.GA19409@x1>
Date:	Mon, 24 Aug 2015 16:51:29 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Vaibhav Hiremath <vaibhav.hiremath@...aro.org>
Cc:	linux-arm-kernel@...ts.infradead.org, Zhao Ye <zhaoy@...vell.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH-v6 5/6] mfd: 88pm800: Set default interrupt clear method

On Mon, 24 Aug 2015, Vaibhav Hiremath wrote:

> 
> 
> On Monday 24 August 2015 07:24 PM, Lee Jones wrote:
> >On Wed, 08 Jul 2015, Vaibhav Hiremath wrote:
> >
> >>As per the spec, bit 1 (INT_CLEAR_MODE) of reg addr 0xe
> >>(page 0) controls the method of clearing interrupt
> >>status of 88pm800 family of devices;
> >>
> >>   0: clear on read
> >>   1: clear on write
> >>
> >>If pdata is not coming from board file, then set the
> >>default irq clear method to "irq clear on write"
> >>
> >>Also, as suggested by "Lee Jones" renaming variable field
> >>to appropriate name and removed unnecessary field
> >>pm80x_chip.irq_mode, using platform_data.irq_clr_method.
> >>
> >>Signed-off-by: Zhao Ye <zhaoy@...vell.com>
> >>Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@...aro.org>
> >>Reviewed-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> >>---
> >>  drivers/mfd/88pm800.c       | 15 ++++++++++-----
> >>  include/linux/mfd/88pm80x.h |  9 +++++++--
> >>  2 files changed, 17 insertions(+), 7 deletions(-)
> >
> >[...]
> >
> >>+#define PM800_WAKEUP2_INT_READ_CLEAR	(0 << 1)
> >>+#define PM800_WAKEUP2_INT_WRITE_CLEAR	(1 << 1)
> >
> >Use BIT().
> >
> >>+/* Used by irq_clr_method */
> >>+#define PM800_IRQ_CLR_ON_READ	0
> >>+#define PM800_IRQ_CLR_ON_WRITE	1
> >
> >>-	int irq_mode;		/* Clear interrupt by read/write(0/1) */
> >>+	bool irq_clr_method;		/* Clear interrupt by read/write(0/1) */
> >
> >>+	irq_clr_mode = pdata->irq_clr_method == PM800_IRQ_CLR_ON_WRITE ?
> >>+		PM800_WAKEUP2_INT_WRITE_CLEAR : PM800_WAKEUP2_INT_READ_CLEAR;
> >>+	ret = regmap_update_bits(map, PM800_WAKEUP2, mask, irq_clr_mode);
> >
> >This is pretty convoluted.
> >
> >For starters you're abusing the 'bool' type here.  Bool is either
> >'true' or 'false', so at the very least you should rename
> >'irq_clr_method' to 'irq_clr_on_write'.
> >
> >Then you can do:
> >
> >	irq_clr_mode = pdata->irq_clr_on_write ?
> >		PM800_WAKEUP2_INT_WRITE_CLEAR : PM800_WAKEUP2_INT_READ_CLEAR;
> >
> 
> We have discussed on this, and went back-n-forth.
> I think if I remember correctly, one of the version was using
> true/false then we decided to rename it to relevant macro.
> 
> If I am not wrong V4 version of this series is exactly same as what you
> are referring to.

Right.  I made a few suggestions which vary in usefulness depending on
how you plan to implement all of this.  Unfortunately this is a bit of
a bastardised version where some of it make sense and other parts
could do with some improvement.

> >However, what I suggest you really do is share
> >PM800_WAKEUP2_INT_{READ,WRITE}_CLEAR with platform data and just pass
> >the value through directly.
> >
> 
> I think we discussed about this also, and the reason I recall here is,
> 
> we may need to control this from DT in the future so we decided to keep
> it boolean in platform_data and have simple check before writing to
> register.
> 
> And I think that was also another reason we introduced
> 
> /* Used by irq_clr_method */
> #define PM800_IRQ_CLR_ON_READ   0
> #define PM800_IRQ_CLR_ON_WRITE  1

I think these are still required.  So it would look like this:

== Platform data ==

struct pdata {
  bool clear_irq_on_write;
};

pdata->clear_irq_on_write = PM800_IRQ_CLR_ON_{READ,WRITE};

== Driver ==

irq_clr_mode = pdata->clear_irq_on_write ?
                 PM800_WAKEUP2_INT_WRITE_CLEAR : PM800_WAKEUP2_INT_READ_CLEAR;
regmap_update_bits(map, PM800_WAKEUP2, mask, irq_clr_mode);

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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