linux-kernel - Re: [RFC PATCH 3/4] ARM: l2x0: add arm,ecc-enable property for aurora

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Message-ID: <1498142790.2533.80.camel@pengutronix.de>
Date:   Thu, 22 Jun 2017 16:46:30 +0200
From:   Jan Lübbe <jlu@...gutronix.de>
To:     Chris Packham <Chris.Packham@...iedtelesis.co.nz>
Cc:     "bp@...en8.de" <bp@...en8.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 3/4] ARM: l2x0: add arm,ecc-enable property for
 aurora

Chris,

On So, 2017-06-11 at 22:55 +0000, Chris Packham wrote:
> On 09/06/17 20:58, Jan Lübbe wrote:
> > On Do, 2017-06-08 at 16:11 +1200, Chris Packham wrote:
> >> +       if (of_property_read_bool(np, "arm,ecc-enable")) {
> >> +               mask |= L2C_AUX_CTRL_EVTMON_ENABLE;
> >> +               val |= L2C_AUX_CTRL_EVTMON_ENABLE;
> >> +       } else if (of_property_read_bool(np, "arm,ecc-disable")) {
> >> +               mask |= L2C_AUX_CTRL_EVTMON_ENABLE;
> >> +       }
> > 
> > Unless I misunderstand the code in __l2c_init(), the mask is used to
> > specify the bits to preserve:
> >          old_aux = aux = readl_relaxed(l2x0_base + L2X0_AUX_CTRL);
> >          aux &= aux_mask;
> >          aux |= aux_val;
> > 
> >          if (old_aux != aux)
> >                  pr_warn("L2C: DT/platform modifies aux control register: 0x%08x -> 0x%08x\n",
> >                          old_aux, aux);
> > 
> > So the arm,ecc-disable property will have no effect. This probably also
> > applies to patch 2/4. The existing property *-disable code removes the
> > corresponding bit from the mask.
> 
> Indeed the disable version should be mask &= ~L2C_AUX_CTRL_EVTMON_ENABLE 
> and I was probably a little lazy to have used the L2C EVTMON instead of 
> adding AURORA specific ones like you have in your series.
> 
> I'll rebase my series on top of yours and send it direct to you so you 
> can include it in the overall submission.

While picking up your arm,parity-enable and arm,ecc-enable patches for
my series, I noticed that the mask variable is inverted when merging the
local changes into aux_val/aux_mask at the end of aurora_of_parse. So I
now believe your code is correct. ;) I'd appreciate a close look,
nevertheless.

Regards,
Jan