linux-kernel - Re: [PATCH 3/3] soc: qcom: Add AOSS QMP genpd provider

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Message-ID: <20181226203032.GF9704@minitux>
Date:   Wed, 26 Dec 2018 12:30:33 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] soc: qcom: Add AOSS QMP genpd provider

On Mon 26 Nov 19:31 PST 2018, Sai Prakash Ranjan wrote:

> Hi Bjorn,
> 

Thanks for your review Sai!

> On 11/12/2018 1:35 PM, Bjorn Andersson wrote:
[..]
> > +static int qmp_pd_clock_toggle(struct qmp_pd *res, bool enable)
> > +{
> > +	char buf[96];
> > +	size_t n;
> > +
> > +	n = snprintf(buf, sizeof(buf), "{class: clock, res: %s, val: %d}",
> > +		     res->name, !!enable);
> > +	return qmp_send(res->qmp, buf, n);
> > +}
> > +
> 
> I was trying to get QDSS working with these patches and found one issue
> in qmp_send of qmp_pd_clock_toggle.
> 
> The third return value should be sizeof(buf) instead of n because n just
> returns len as 33 and the below check in qmp send will always fail and
> trigger WARN_ON's.
> 
>          if (WARN_ON(len % sizeof(u32))) {
>                  dev_err(qmp->dev, "message not 32-bit aligned\n");
>                  return -EINVAL;
>          }
> 
> Also I observed that multiple "ucore will not ack channel" messages with
> len being returned n instead of buf size.
> 

I must have been "lucky" when I did my final pass of cleanups and
retests, thanks for spotting this!

> One more thing is do we really require *WARN_ON and dev_err* both because it
> just spams the kernel logs, I think dev_err message is clear
> enough to be able to understand the error condition.
> 

No, that's just unnecessary.

Regards,
Bjorn