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

[Lee Jones]

On Mon, 24 Aug 2015, Vaibhav Hiremath wrote:

> 
> 
> On Monday 24 August 2015 09:21 PM, Lee Jones wrote:
> >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@xxxxxxxxxxx>
> >>>>Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
> >>>>Reviewed-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
> >>>>---
> >>>>  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.
> >
> 
> This so called "basterdised version could have been avoided :)
> 
> V2 version itself was clean and ready. It just got dragged into
> multiple iterations.

Don't kid yourself.  There were still improvements to be made.

> >>>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:
> >
> 
> NO. I think you are confused here,
> We have two different macros playing around here,
> 
> 
> +/* Used by irq_clr_method */
> +#define PM800_IRQ_CLR_ON_READ	0
> +#define PM800_IRQ_CLR_ON_WRITE	1
> 
> /* Used to write to register */
> +#define PM800_WAKEUP2_INT_READ_CLEAR		(0 << 1)
> +#define PM800_WAKEUP2_INT_WRITE_CLEAR		(1 << 1)

I know.  I used both of them *correctly* in my example below.  No
confusion here.

> >== 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);
> >
> 
> Please check V2, which is exactly same as above.
> 
> https://patchwork.kernel.org/patch/6627781/
> 
> 
> If you are OK with it, I will spin another version and submit it.

If you can't use the value directly, which if you want to pull the
value from DT you can't, then either use the method above, or
something like this might be better:

int clear_on_write = 0;

if (pdata->clear_irq_on_write)
   clear_on_write = PM800_WAKEUP2_INT_WRITE_CLEAR;

.. this way you only need to add one new define and you can drop
PM800_WAKEUP2_INT_READ_CLEAR altogether.  This is better, because it
will aid you to move to the BIT() macro easier (there is no BIT()
value for shifting 0's).

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