From: Jassi Brar <jassisinghbrar@gmail.com>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>,
Martin Botka <martin.botka@somainline.org>,
~postmarketos/upstreaming@lists.sr.ht,
Konrad Dybcio <konrad.dybcio@somainline.org>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@somainline.org>,
Marijn Suijten <marijn.suijten@somainline.org>,
jamipkettunen@somainline.org, Andy Gross <agross@kernel.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V3 3/3] mailbox: qcom-apcs: Add SM6125 compatible
Date: Mon, 21 Jun 2021 22:34:37 -0500 [thread overview]
Message-ID: <CABb+yY3RpQYvNBHvpwZearpBPph0uj8YQwX2qu=TX=QAO6OFBw@mail.gmail.com> (raw)
In-Reply-To: <YNFKpvhXyZbs8RE1@yoga>
On Mon, Jun 21, 2021 at 9:27 PM Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On Mon 21 Jun 20:00 CDT 2021, Jassi Brar wrote:
>
> > On Mon, Jun 21, 2021 at 6:35 PM Bjorn Andersson
> > <bjorn.andersson@linaro.org> wrote:
> > >
> > > On Mon 21 Jun 18:19 CDT 2021, Rob Herring wrote:
> > >
> > > > On Mon, Jun 21, 2021 at 5:10 PM Jassi Brar <jassisinghbrar@gmail.com> wrote:
> > > > >
> > > > > On Mon, Jun 21, 2021 at 2:46 PM Rob Herring <robh+dt@kernel.org> wrote:
> > > > > >
> > > > > > On Sun, Jun 20, 2021 at 10:03 PM Jassi Brar <jassisinghbrar@gmail.com> wrote:
> > > > > > >
> > > > > > > On Sat, Jun 12, 2021 at 4:46 AM Martin Botka
> > > > > > > <martin.botka@somainline.org> wrote:
> > > > > > > >
> > > > > > > > This commit adds compatible for the SM6125 SoC
> > > > > > > >
> > > > > > > > Signed-off-by: Martin Botka <martin.botka@somainline.org>
> > > > > > > > ---
> > > > > > > > Changes in V2:
> > > > > > > > None
> > > > > > > > Changes in V3:
> > > > > > > > Change compatible to apcs-hmss-global
> > > > > > > > drivers/mailbox/qcom-apcs-ipc-mailbox.c | 5 +++++
> > > > > > > > 1 file changed, 5 insertions(+)
> > > > > > > >
> > > > > > > > diff --git a/drivers/mailbox/qcom-apcs-ipc-mailbox.c b/drivers/mailbox/qcom-apcs-ipc-mailbox.c
> > > > > > > > index f25324d03842..f24c5ad8d658 100644
> > > > > > > > --- a/drivers/mailbox/qcom-apcs-ipc-mailbox.c
> > > > > > > > +++ b/drivers/mailbox/qcom-apcs-ipc-mailbox.c
> > > > > > > > @@ -57,6 +57,10 @@ static const struct qcom_apcs_ipc_data sdm660_apcs_data = {
> > > > > > > > .offset = 8, .clk_name = NULL
> > > > > > > > };
> > > > > > > >
> > > > > > > > +static const struct qcom_apcs_ipc_data sm6125_apcs_data = {
> > > > > > > > + .offset = 8, .clk_name = NULL
> > > > > > > > +};
> > > > > > > > +
> > > > > > > > static const struct qcom_apcs_ipc_data apps_shared_apcs_data = {
> > > > > > > > .offset = 12, .clk_name = NULL
> > > > > > > > };
> > > > > > > > @@ -166,6 +170,7 @@ static const struct of_device_id qcom_apcs_ipc_of_match[] = {
> > > > > > > > { .compatible = "qcom,sc8180x-apss-shared", .data = &apps_shared_apcs_data },
> > > > > > > > { .compatible = "qcom,sdm660-apcs-hmss-global", .data = &sdm660_apcs_data },
> > > > > > > > { .compatible = "qcom,sdm845-apss-shared", .data = &apps_shared_apcs_data },
> > > > > > > > + { .compatible = "qcom,sm6125-apcs-hmss-global", .data = &sm6125_apcs_data },
> > > > > > > > { .compatible = "qcom,sm8150-apss-shared", .data = &apps_shared_apcs_data },
> > > > > > > > { .compatible = "qcom,sdx55-apcs-gcc", .data = &sdx55_apcs_data },
> > > > > > > > {}
> > > > > > > >
> > > > > > > These all are basically different names for the same controller.
> > > > > > > The 'offset' is a configuration parameter and the 'clock', when NULL,
> > > > > > > is basically some "always-on" clock.
> > > > > > > I am sure we wouldn't be doing it, if the controller was third-party.
> > > > > >
> > > > > > If newer implementations are 'the same', then they should have a
> > > > > > fallback compatible to the existing one that is the same and no driver
> > > > > > change is needed. If the differences are board or instance (within an
> > > > > > SoC) specific, then a DT property would be appropriate.
> > > > > >
> > > > > The controllers (13 now) only differ by the 'offset' where the
> > > > > registers are mapped. Clock-name is a pure s/w artifact.
> > > > > So, maybe we could push all these in DT.
> > > >
> > > > Why is 'reg' not used for the offset?
> > > >
> > >
> > > The DT node and its "reg" describes the whole IP block.
> > >
> > > The particular register that we care of has, as you can see, moved
> > > around during the various platforms and some incarnations of this IP
> > > block provides controls for CPU-related clocks as well.
> > >
> > > We can certainly have the multiple compatible points to the same
> > > apcs_data, but I'm not able to spot a reasonable "catch-all compatible"
> > > given that I don't see any natural groupings.
> > >
> > Any platform that comes later may reuse the already available compatible.
> > For example drop this patch and reuse "qcom,sdm660-apcs-hmss-global" ?
> >
>
> The problem is that this would change the meaning of
> "qcom,sdm660-apcs-hmss-global" from meaning "The apcs hmss global block
> _in_ sdm660" to "any random apcs block with the mailbox register at
> offset 8".
>
To me, the deeper problem seems to be naming a controller "The apcs
hmss global block _in_ sdm660" just because the h/w manual hasn't
given a name to it. But that is okay too, if we name the subsequent
controllers as "the same as one in sdm660" and provide the h/w
configuration 'offset' via a DT property.
> > > > In any case, we can't really get rid of the first 13 instances though...
> > > >
> > >
> > > Right, we have the problem that we have DTBs out there that relies on
> > > these compatibles, but as Jassi requests we'd have to start describing
> > > the internal register layout in DT - which this binding purposefully
> > > avoids.
> > >
> > Not these strings, but 'offset' and 'clock-name' as optional
> > properties that new platforms can use.
> >
>
> Relying on completely generic compatibles to match the driver and then
> distinguish each platform using additional properties is exactly what
> Qualcomm does downstream. The community has clarified countless times
> that this is not the way to write DT bindings.
>
Yes, and I don't suggest it otherwise. For h/w quirks and
extra/missing features, it does make sense to have different
compatibles.
However, for _trivial_ variations let us get that value from DT.
'offset' is anyway a h/w property.
That way we won't be distinguishing platforms using dt properties, but
only support different platforms seamlessly.
On second thought, we have grown from 2 to 13 aliases in 4 yrs. I only
have to ignore 3 times/annum to lead a peaceful life ;)
thnx.
next prev parent reply other threads:[~2021-06-22 3:34 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-12 9:46 [PATCH V3 1/3] socinfo: Add missing SoC ID for SM6125 Martin Botka
2021-06-12 9:46 ` [PATCH V3 2/3] dt-bindings: mailbox: Add binding for sm6125 Martin Botka
2021-06-24 19:26 ` Rob Herring
2021-06-12 9:46 ` [PATCH V3 3/3] mailbox: qcom-apcs: Add SM6125 compatible Martin Botka
2021-06-21 4:03 ` Jassi Brar
2021-06-21 17:02 ` Martin Botka
2021-06-21 19:46 ` Rob Herring
2021-06-21 23:10 ` Jassi Brar
2021-06-21 23:19 ` Rob Herring
2021-06-21 23:35 ` Bjorn Andersson
2021-06-22 1:00 ` Jassi Brar
2021-06-22 2:27 ` Bjorn Andersson
2021-06-22 3:34 ` Jassi Brar [this message]
2021-06-22 3:52 ` Bjorn Andersson
2021-06-22 14:36 ` AngeloGioacchino Del Regno
2021-06-22 14:43 ` Jassi Brar
2021-06-24 21:07 ` Bjorn Andersson
2021-06-24 22:59 ` AngeloGioacchino Del Regno
2021-06-25 0:02 ` Bjorn Andersson
2021-06-26 16:50 ` Jassi Brar
2021-06-22 14:37 ` Jassi Brar
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