netdev - RE: [PATCH v2 lora-next 1/4] net: lora: sx1301: convert burst spi functions to regmap raw

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Date:   Wed, 10 Oct 2018 09:22:25 +0000
From:   Ben Whitten <Ben.Whitten@...rdtech.com>
To:     Andreas Färber <afaerber@...e.de>,
        Ben Whitten <ben.whitten@...il.com>,
        Mark Brown <broonie@...nel.org>
CC:     "starnight@...cu.edu.tw" <starnight@...cu.edu.tw>,
        "hasnain.virk@....com" <hasnain.virk@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "liuxuenetmail@...il.com" <liuxuenetmail@...il.com>,
        "shess@...sware.de" <shess@...sware.de>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        Stefan Popa <stefan.popa@...log.com>
Subject: RE: [PATCH v2 lora-next 1/4] net: lora: sx1301: convert burst spi
 functions to regmap raw

> Subject: Re: [PATCH v2 lora-next 1/4] net: lora: sx1301:
> convert burst spi functions to regmap raw
> 
> Hi Ben and Mark,
> 
> Am 09.10.18 um 14:52 schrieb Ben Whitten:
> > As we have caching disabled we can access the regmap
> using raw for our
> > firmware reading and writing bursts.
> > We also remove the now defunct spi element from the
> structure as this
> > completes the move to regmap.
> >
> > Signed-off-by: Ben Whitten
> <ben.whitten@...rdtech.com>
> > ---
> >  drivers/net/lora/sx1301.c | 26 +++++++++++++++++------
> ---
> >  drivers/net/lora/sx1301.h |  2 --
> >  2 files changed, 17 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/net/lora/sx1301.c
> b/drivers/net/lora/sx1301.c
> > index fd29258..5ab0e2d 100644
> > --- a/drivers/net/lora/sx1301.c
> > +++ b/drivers/net/lora/sx1301.c
> > @@ -76,19 +76,28 @@ static struct regmap_config
> sx1301_regmap_config = {
> >
> >  static int sx1301_read_burst(struct sx1301_priv *priv, u8
> reg, u8 *val, size_t len)
> >  {
> > -	u8 addr = reg & 0x7f;
> > -	return spi_write_then_read(priv->spi, &addr, 1, val,
> len);
> > +	size_t max;
> > +
> > +	max = regmap_get_raw_read_max(priv->regmap);
> > +	if (max && max < len) {
> > +		dev_err(priv->dev, "Burst greater then max
> raw read\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	return regmap_raw_read(priv->regmap, reg, val,
> len);
> 
> I believe the way we are using it with a single register needs
> regmap_noinc_read() instead, in case we ever want to
> enable caching? ...

Certainly, the noinc was introduced in 4.19 lets rebase lora-next
and use this API instead.

> 
> >  }
> >
> >  static int sx1301_write_burst(struct sx1301_priv *priv, u8
> reg, const u8 *val, size_t len)
> >  {
> > -	u8 addr = reg | BIT(7);
> > -	struct spi_transfer xfr[2] = {
> > -		{ .tx_buf = &addr, .len = 1 },
> > -		{ .tx_buf = val, .len = len },
> > -	};
> > +	size_t max;
> > +
> > +	max = regmap_get_raw_write_max(priv->regmap);
> > +	if (max && max < len) {
> > +		dev_err(priv->dev, "Burst greater then max
> raw write\n");
> > +		return -EINVAL;
> > +	}
> >
> > -	return spi_sync_transfer(priv->spi, xfr, 2);
> > +	return regmap_raw_write(priv->regmap, reg, val,
> len);
> 
> ... Which would mean we are lacking a noinc API for write
> here!
> 
> @Mark/Stefan, any reason noinc was not implemented
> symmetrically?
> 
> For sx1276 I have local regmap conversion patches, but I
> kept getting
> -EINVAL for bursts and haven't figured out why yet. Need to
> compare to
> your code - I assume you successfully tested this, Ben.

Yes I was able to load and verify/run the firmware using this
patch on my Sentrius RG1xx board.

Thanks,
Ben