linux-kernel - RE: Re: iio: filter: admv8818: Force initialization of SDO

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Message-ID:
 <SA1P110MB10690D050787621F1C96AE70BCE8A@SA1P110MB1069.NAMP110.PROD.OUTLOOK.COM>
Date: Fri, 31 Jan 2025 12:30:25 +0000
From: Sam Winchenbach <swinchenbach@...a.org>
To: Jonathan Cameron <jic23@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"antoniu.miclaus@...log.com" <antoniu.miclaus@...log.com>, "lars@...afoo.de"
	<lars@...afoo.de>, "Michael.Hennerich@...log.com"
	<Michael.Hennerich@...log.com>
Subject: RE: Re: iio: filter: admv8818: Force initialization of SDO

> Hi Sam, we shouldn't be seeing the email header in the patch.
> 
> I can tidy that up if you can't fix it though.
> >
> > When a weak pull-up is present on the SDO line, regmap_update_bits 
> > fails to write both the SOFTRESET and SDOACTIVE bits because it 
> > incorrectly reads them as already set.
> >
> > Since the soft reset disables the SDO line, performing a 
> > read-modify-write operation on ADI_SPI_CONFIG_A to enable the SDO line 
> > doesn't make sense. This change directly writes to the register 
> > instead of using regmap_update_bits.
> >
> Sounds like a fix, so could you send an appropriate Fixes tag in a v2 and/or a reply to this email.

Added the fixes tag and submitted as patch v2. Please let me know if there is anything else that is needed.
Thanks.

> 
> > Signed-off-by: Sam Winchenbach <swinchenbach@...a.org>
> > ---
> >  drivers/iio/filter/admv8818.c | 14 ++++----------
> >  1 file changed, 4 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/iio/filter/admv8818.c 
> > b/drivers/iio/filter/admv8818.c index 195e58bc4..9cd1eee84 100644
> > --- a/drivers/iio/filter/admv8818.c
> > +++ b/drivers/iio/filter/admv8818.c
> > @@ -577,21 +577,15 @@ static int admv8818_init(struct admv8818_state *st)
> >       struct spi_device *spi = st->spi;
> >       unsigned int chip_id;
> >
> > -     ret = regmap_update_bits(st->regmap, ADMV8818_REG_SPI_CONFIG_A,
> > -                              ADMV8818_SOFTRESET_N_MSK |
> > -                              ADMV8818_SOFTRESET_MSK,
> > -                              FIELD_PREP(ADMV8818_SOFTRESET_N_MSK, 1) |
> > -                              FIELD_PREP(ADMV8818_SOFTRESET_MSK, 1));
> > +     ret = regmap_write(st->regmap, ADMV8818_REG_SPI_CONFIG_A,
> > +                        ADMV8818_SOFTRESET_N_MSK | 
> > + ADMV8818_SOFTRESET_MSK);
> >       if (ret) {
> >               dev_err(&spi->dev, "ADMV8818 Soft Reset failed.\n");
> >               return ret;
> >       }
> >
> > -     ret = regmap_update_bits(st->regmap, ADMV8818_REG_SPI_CONFIG_A,
> > -                              ADMV8818_SDOACTIVE_N_MSK |
> > -                              ADMV8818_SDOACTIVE_MSK,
> > -                              FIELD_PREP(ADMV8818_SDOACTIVE_N_MSK, 1) |
> > -                              FIELD_PREP(ADMV8818_SDOACTIVE_MSK, 1));
> > +     ret = regmap_write(st->regmap, ADMV8818_REG_SPI_CONFIG_A,
> > +                        ADMV8818_SDOACTIVE_N_MSK | 
> > + ADMV8818_SDOACTIVE_MSK);
> >       if (ret) {
> >               dev_err(&spi->dev, "ADMV8818 SDO Enable failed.\n");
> >               return ret;