linux-kernel - Re: [PATCH v4 2/5] remoteproc: qcom: Introduce driver to store pil info in IMEM

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Message-ID: <20200311233256.GB1214176@minitux>
Date:   Wed, 11 Mar 2020 16:32:56 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Andy Gross <agross@...nel.org>, Ohad Ben-Cohen <ohad@...ery.com>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mathieu Poirier <mathieu.poirier@...aro.org>
Subject: Re: [PATCH v4 2/5] remoteproc: qcom: Introduce driver to store pil
 info in IMEM

On Wed 11 Mar 16:25 PDT 2020, Stephen Boyd wrote:

> Quoting Bjorn Andersson (2020-03-10 14:27:28)
> > On Tue 10 Mar 13:29 PDT 2020, Stephen Boyd wrote:
> > 
> > > Why can't we search in DT for the
> > > imem node and then find the pil reloc info compatible string on the
> > > first call to this library? Then we don't need an API to see if the
> > > device has probed yet (qcom_pil_info_available)
> > 
> > I think this sounds reasonable.
> 
> Great!
> 
> > 
> > > and we can just ioremap
> > > some region of memory that's carved out for this reason. Forcing
> > > everything through the regmap is mostly adding pain.
> > > 
> > 
> > My concern here was simply that we'll end up ioremapping various small
> > chunks of the imem region 10 (or so) times. But I agree that things
> > would be cleaner here.
> 
> Alright. I'd like the ioremap() approach. ioremap() will "do the right
> thing" and reuse mappings if they're already there and overlap in the
> page. So it's OK that the syscon/simple-mfd exists and makes a device,
> etc. etc., but we don't need to care about it. We can just ioremap() the
> area and not worry that the regmap users may have a mapping to the same
> place. This is a dedicated carveout inside IMEM so we're safe from other
> meddling users.

Agreed, thanks for the feedback!

Regards,
Bjorn