Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <1589307480-27508-1-git-send-email-rbokka@codeaurora.org>
 <1589307480-27508-3-git-send-email-rbokka@codeaurora.org> <ffaccce7-95c0-2f95-ad3b-55f1da42eaee@linaro.org>
 <14e1fa51-066c-6e1b-01a4-2103612de9e9@codeaurora.org> <d5902226-21b3-7941-6405-688d7a115142@linaro.org>
 <b80aaca0-0594-e04b-5320-b5b3c4478161@codeaurora.org> <d76e4eb2-fa6a-0b76-3912-83bce678bc96@linaro.org>
 <CAD=FV=XW7GymV_pr_0SvUPWwL6WnPhqMq-crq-RbR_us3-ShNA@mail.gmail.com>
 <9864496c-b066-3fe8-5608-bd9af69663f4@linaro.org> <CAD=FV=UbZPQ74COXJbOikq9Wcx1UvtuMuMA+nqkx44uySoqggg@mail.gmail.com>
 <99f07eaa-d072-f391-098e-e6f7a50a1960@linaro.org>
In-Reply-To: <99f07eaa-d072-f391-098e-e6f7a50a1960@linaro.org>
From:   Doug Anderson <dianders@chromium.org>
Date:   Thu, 21 May 2020 08:10:35 -0700
Message-ID: <CAD=FV=W+UES1f3reMhvPPUho5FbaZXdU-2jkRaPcbBEzDWT+WQ@mail.gmail.com>
Subject: Re: [RFC v1 2/3] drivers: nvmem: Add driver for QTI qfprom-efuse support
To:     Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc:     "Ravi Kumar Bokka (Temp)" <rbokka@codeaurora.org>,
        Rob Herring <robh+dt@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Rajendra Nayak <rnayak@codeaurora.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
        dhavalp@codeaurora.org, mturney@codeaurora.org,
        sparate@codeaurora.org, c_rbokka@codeaurora.org,
        mkurumel@codeaurora.org
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi,

On Thu, May 21, 2020 at 8:01 AM Srinivas Kandagatla
<srinivas.kandagatla@linaro.org> wrote:
>
> On 20/05/2020 23:48, Doug Anderson wrote:
> >> Is this only applicable for corrected address space?
> > I guess I was proposing a two dts-node / two drive approach here.
> >
> > dts node #1:just covers the memory range for accessing the FEC-corrected data
> > driver #1: read-only and reads the FEC-corrected data
> >
> > dts node #2: covers the memory range that's_not_  the FEC-corrected
> > memory range.
> > driver #2: read-write.  reading reads uncorrected data
> >
> > Does that seem sane?
>
> I see your point but it does not make sense to have two node for same thing.

OK, so that sounds as if we want to go with the proposal where we
"deprecate the old driver and/or bindings and say that there really
should just be one node and one driver".

Would this be acceptable to you?

1. Officially mark the old bindings as deprecated.

2. Leave the old driver there to support the old deprecated bindings,
at least until everyone can be transferred over.  There seem to be
quite a few existing users of "qcom,qfprom" and we're supposed to make
an attempt at keeping the old device trees working, at least for a
little while.  Once everyone is transferred over we could decide to
delete the old driver.

3. We will have a totally new driver here.

4. A given device tree will _not_ be allowed to have both
"qcom,qfprom" specified and "qcom,SOC-qfprom" specified.  ...and by
"qcom,SOC-qfprom" I mean that SOC should be replaced by the SoC name,
so "qcom,sc7180-qfprom" or "qcom,sdm845-qfprom".  So once you switch
to the new node it replaces the old node.


> Isn't the raw address space reads used to for blowing and checking the
> fuses if they are blown correctly or not and software usage of these
> fuses should only be done from correct address space?
>
> the read interface to user should be always from corrected address space
> and write interface should be to raw address space.

Great.  That sounds right to me.  Presumably the driver could add some
sort of "debugfs" access to read the raw address space if needed.

-Doug