linux-kernel - Re: [PATCH 1/2] extcon: ptn5150: Use defines for registers

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Message-ID: <20200911053805.GA2954@kozik-lap>
Date:   Fri, 11 Sep 2020 07:38:05 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Chanwoo Choi <cw00.choi@...sung.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Vijai Kumar K <vijaikumar.kanagarajan@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] extcon: ptn5150: Use defines for registers

On Fri, Sep 11, 2020 at 12:14:19PM +0900, Chanwoo Choi wrote:
> On 9/10/20 12:01 AM, Krzysztof Kozlowski wrote:
> > The register addresses are not continuous, so use simple defines for
> > them.  This also makes it easier to find the address for register.
> > 
> > No functional change.
> > 
> > Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> > ---
> >  drivers/extcon/extcon-ptn5150.c | 22 ++++++++++------------
> >  1 file changed, 10 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/extcon/extcon-ptn5150.c b/drivers/extcon/extcon-ptn5150.c
> > index dda5b3a3a908..1b68f56d8372 100644
> > --- a/drivers/extcon/extcon-ptn5150.c
> > +++ b/drivers/extcon/extcon-ptn5150.c
> > @@ -19,18 +19,16 @@
> >  #include <linux/gpio/consumer.h>
> >  
> >  /* PTN5150 registers */
> > -enum ptn5150_reg {
> > -	PTN5150_REG_DEVICE_ID = 0x01,
> > -	PTN5150_REG_CONTROL,
> > -	PTN5150_REG_INT_STATUS,
> > -	PTN5150_REG_CC_STATUS,
> > -	PTN5150_REG_CON_DET = 0x09,
> > -	PTN5150_REG_VCONN_STATUS,
> > -	PTN5150_REG_RESET,
> > -	PTN5150_REG_INT_MASK = 0x18,
> > -	PTN5150_REG_INT_REG_STATUS,
> > -	PTN5150_REG_END,
> > -};
> > +#define PTN5150_REG_DEVICE_ID			0x01
> > +#define PTN5150_REG_CONTROL			0x02
> > +#define PTN5150_REG_INT_STATUS			0x03
> > +#define PTN5150_REG_CC_STATUS			0x04
> > +#define PTN5150_REG_CON_DET			0x09
> > +#define PTN5150_REG_VCONN_STATUS		0x0a
> > +#define PTN5150_REG_RESET			0x0b
> > +#define PTN5150_REG_INT_MASK			0x18
> > +#define PTN5150_REG_INT_REG_STATUS		0x19
> > +#define PTN5150_REG_END				PTN5150_REG_INT_REG_STATUS
> 
> PTN5150_REG_END should be (PTN5150_REG_INT_REG_STATUS + 1)
> for regmap operation of PTN5150_REG_INT_REG_STATUS.

Why? This goes to regmap's max_register which is the last register
allowed to read:

  drivers/base/regmap/regmap-debugfs.c:   for (i = 0; i <= map->max_register; i += map->reg_stride) {
  drivers/base/regmap/regmap.c:   if (map->max_register && reg > map->max_register)

  regmap_get_max_register() - Report the max register value

Best regards,
Krzysztof