linux-kernel - Re: [PATCH] mailbox: qcom-apcs-ipc: use PLATFORM_DEVID

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Message-ID: <X9klmVX576ePRiAr@builder.lan>
Date:   Tue, 15 Dec 2020 15:07:37 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Shawn Guo <shawn.guo@...aro.org>
Cc:     Jassi Brar <jassisinghbrar@...il.com>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konradybcio@...il.com>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mailbox: qcom-apcs-ipc: use PLATFORM_DEVID_AUTO to
 register device

On Fri 11 Dec 08:12 CST 2020, Shawn Guo wrote:

> On Fri, Dec 11, 2020 at 12:16 PM Bjorn Andersson
> <bjorn.andersson@...aro.org> wrote:
> >
> > On Mon 12 Oct 21:12 CDT 2020, Shawn Guo wrote:
> >
> > > On MSM8916, only one qcom-apcs-msm8916-clk device is needed, as there is
> > > only one APCS clock.  However, on MSM8939 three APCS clocks need to be
> > > registered for cluster0 (little cores), cluster1 (big cores) and CCI
> > > (Cache Coherent Interconnect).  That said, we will need to register 3
> > > qcom-apcs-msm8916-clk devices.  Let's use PLATFORM_DEVID_AUTO rather
> > > than PLATFORM_DEVID_NONE for platform_device_register_data() call.
> > > Otherwise, the second APCS clock registration will fail due to duplicate
> > > device name.
> > >
> > > [    0.519657] sysfs: cannot create duplicate filename '/bus/platform/devices/qcom-apcs-msm8916-clk'
> > > ...
> > > [    0.661158] qcom_apcs_ipc b111000.mailbox: failed to register APCS clk
> > >
> >
> > Spotted this as I was looking for another patch, hence the late reply.
> > But it seems this was never reviewed or merged.
> >
> > What does the bigger picture look like? Do we have 3 APCS global, or
> > it's a single memory region that provides the 3 clocks? How does the
> > qcom-apcs-msm8916-clk with it's hard coded offset of 0x50 deal with
> > this? (Is this a single qcom-apcs-msm8939-clk that registers 3 clocks
> > instead? Making this patch unnecessary?)
> 
> We have 3 APCS global instances.  I haven't got time to send out other
> related patches, but the DT for these 3 APCS global looks like below.
> 
>                 apcs2: mailbox@...1000 {
>                         compatible = "qcom,msm8916-apcs-kpss-global", "syscon";
>                         reg = <0xb1d1000 0x1000>;
>                         #mbox-cells = <1>;

The thing at 0xb1d1000 does not have the IPC bits, so this shouldn't
have the #mbox-cells.

Other than that, this seems to be correct. Please do add the msm8939
compatible as you send this out.

Regards,
Bjorn

>                         clocks = <&a53pll_cci>, <&gcc GPLL0_VOTE>;
>                         clock-names = "pll", "aux";
>                         #clock-cells = <0>;
>                         clock-output-names = "a53mux_cci";
>                 };
> 
>                 apcs1: mailbox@...1000 {
>                         compatible = "qcom,msm8916-apcs-kpss-global", "syscon";
>                         reg = <0xb011000 0x1000>;
>                         #mbox-cells = <1>;
>                         clocks = <&a53pll_c1>, <&gcc GPLL0_VOTE>;
>                         clock-names = "pll", "aux";
>                         #clock-cells = <0>;
>                         clock-output-names = "a53mux_c1";
>                 };
> 
>                 apcs0: mailbox@...1000 {
>                         compatible = "qcom,msm8916-apcs-kpss-global", "syscon";
>                         reg = <0xb111000 0x1000>;
>                         #mbox-cells = <1>;
>                         clocks = <&a53pll_c0>, <&gcc GPLL0_VOTE>;
>                         clock-names = "pll", "aux";
>                         #clock-cells = <0>;
>                         clock-output-names = "a53mux_c0";
>                 };
> 
> Shawn