linux-kernel - Re: [PATCH 3/3] i2c: rcar: add FastMode+ support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZPgl4eLYTyDFXiyC@shikoro>
Date:   Wed, 6 Sep 2023 09:10:25 +0200
From:   Wolfram Sang <wsa+renesas@...g-engineering.com>
To:     Andi Shyti <andi.shyti@...nel.org>
Cc:     linux-renesas-soc@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] i2c: rcar: add FastMode+ support

Hi Andi,

> > @@ -217,7 +228,17 @@ static void rcar_i2c_init(struct rcar_i2c_priv *priv)
> >  	rcar_i2c_write(priv, ICMCR, MDBS);
> >  	rcar_i2c_write(priv, ICMSR, 0);
> >  	/* start clock */
> > -	rcar_i2c_write(priv, ICCCR, priv->icccr);
> > +	if (priv->flags & ID_P_FMPLUS) {
> > +		rcar_i2c_write(priv, ICCCR, 0);
> > +		rcar_i2c_write(priv, ICMPR, priv->clock_val);
> > +		rcar_i2c_write(priv, ICHPR, 3 * priv->clock_val);
> > +		rcar_i2c_write(priv, ICLPR, 3 * priv->clock_val);
> > +		rcar_i2c_write(priv, ICCCR2, FMPE | CDFD | HLSE | SME);
> > +	} else {
> > +		rcar_i2c_write(priv, ICCCR, priv->clock_val);
> > +		if (priv->devtype >= I2C_RCAR_GEN3)
> > +			rcar_i2c_write(priv, ICCCR2, 0);
> 
> is this last bit part of the FM+ enabling or is it part of the
> GEN4 support?

It is "disabling FM+" for lower speeds. Since we never used ICCCR2
before FM+, we need to make sure it is cleared properly.

> > +		for (scgd = 0; scgd < 0x40; scgd++) {
> > +			scl = ick / (20 + (scgd * 8) + round);
> > +			if (scl <= t.bus_freq_hz)
> > +				break;
> > +		}
> > +
> > +		if (scgd == 0x40) {
> 
> would be nice to give a meaning to this 0x40 constant... either
> having it in a define or a comment, at least.

This code existed before and was just moved into an if-body. It will be
updated in another series following this one.

Thanks for the review,

   Wolfram


Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)