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Subject: Re: [PATCH v10 5/7] interconnect: qcom: Add sdm845 interconnect
 provider driver
To:     Georgi Djakov <georgi.djakov@linaro.org>,
        Evan Green <evgreen@chromium.org>
Cc:     linux-pm@vger.kernel.org, gregkh@linuxfoundation.org,
        rjw@rjwysocki.net, robh+dt@kernel.org,
        Michael Turquette <mturquette@baylibre.com>,
        khilman@baylibre.com, Vincent Guittot <vincent.guittot@linaro.org>,
        Saravana Kannan <skannan@codeaurora.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        amit.kucheria@linaro.org, seansw@qti.qualcomm.com,
        mark.rutland@arm.com, lorenzo.pieralisi@arm.com,
        Alexandre Bailon <abailon@baylibre.com>,
        maxime.ripard@bootlin.com, Arnd Bergmann <arnd@arndb.de>,
        thierry.reding@gmail.com, ksitaraman@nvidia.com,
        sanjayc@nvidia.com, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org
References: <20181127180349.29997-1-georgi.djakov@linaro.org>
 <20181127180349.29997-6-georgi.djakov@linaro.org>
 <CAE=gft4tO96n0vAubo1_vvcTO4yarDcTNOTuL6cLpmLDDNxrfA@mail.gmail.com>
 <cfcb39ba-860c-5a3f-911f-ab52b5250390@linaro.org>
From:   David Dai <daidavid1@codeaurora.org>
Message-ID: <266c7bf9-18c1-8255-eca2-814aab3850c6@codeaurora.org>
Date:   Thu, 6 Dec 2018 13:53:21 -0800
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On 12/5/2018 8:00 AM, Georgi Djakov wrote:
> Hi Evan,
>
> On 12/1/18 02:39, Evan Green wrote:
>> On Tue, Nov 27, 2018 at 10:04 AM Georgi Djakov <georgi.djakov@linaro.org> wrote:
>>> From: David Dai <daidavid1@codeaurora.org>
>>>
>>> Introduce Qualcomm SDM845 specific provider driver using the
>>> interconnect framework.
>>>
>>> Signed-off-by: David Dai <daidavid1@codeaurora.org>
>>> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
>>> ---
>>>   .../bindings/interconnect/qcom,sdm845.txt     |  24 +
>>>   drivers/interconnect/Kconfig                  |   5 +
>>>   drivers/interconnect/Makefile                 |   1 +
>>>   drivers/interconnect/qcom/Kconfig             |  13 +
>>>   drivers/interconnect/qcom/Makefile            |   5 +
>>>   drivers/interconnect/qcom/sdm845.c            | 836 ++++++++++++++++++
>>>   .../dt-bindings/interconnect/qcom,sdm845.h    | 143 +++
>>>   7 files changed, 1027 insertions(+)
>>>   create mode 100644 Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt
>>>   create mode 100644 drivers/interconnect/qcom/Kconfig
>>>   create mode 100644 drivers/interconnect/qcom/Makefile
>>>   create mode 100644 drivers/interconnect/qcom/sdm845.c
>>>   create mode 100644 include/dt-bindings/interconnect/qcom,sdm845.h
>>>
>>> diff --git a/Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt b/Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt
>>> new file mode 100644
>>> index 000000000000..d45150e99665
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/interconnect/qcom,sdm845.txt
>>> @@ -0,0 +1,24 @@
>>> +Qualcomm SDM845 Network-On-Chip interconnect driver binding
>>> +-----------------------------------------------------------
>>> +
>>> +SDM845 interconnect providers support system bandwidth requirements through
>>> +RPMh hardware accelerators known as Bus Clock Manager(BCM). The provider is able
>>> +to communicate with the BCM through the Resource State Coordinator(RSC)
>>> +associated with each execution environment. Provider nodes must reside within
>>> +an RPMh device node pertaining to their RSC and each provider maps to
>>> +a single RPMh resource.
>>> +
>>> +Required properties :
>>> +- compatible : shall contain only one of the following:
>>> +                       "qcom,sdm845-rsc-hlos"
>> I wonder if maybe hlos isn't necessary. Unless you somehow imagine
>> secure mode would have a device tree entry in here as well? Probably
>> not.
> Ok, will remove it. David, please chime in if you have any concerns with
> this.

No strong preferences in terms of naming, but need to make the 
distinction between this and potential other rsc types if we're to add 
additional provider drivers.

>>> +- #interconnect-cells : should contain 1
>>> +
>>> +Examples:
>>> +
>>> +apps_rsc: rsc {
>>> +               qnoc: qnoc-rsc-hlos {
>>> +                       compatible = "qcom,sdm845-rsc-hlos";
>>> +                       #interconnect-cells = <1>;
>>> +               };
>>> +};
>>> +
>> ...
>>> diff --git a/drivers/interconnect/qcom/sdm845.c b/drivers/interconnect/qcom/sdm845.c
>>> new file mode 100644
>>> index 000000000000..1678de91ca52
>>> --- /dev/null
>>> +++ b/drivers/interconnect/qcom/sdm845.c
>>> @@ -0,0 +1,836 @@
>> ...
>>> +
>>> +static void tcs_list_gen(struct list_head *bcm_list,
>>> +                        struct tcs_cmd *tcs_list, int *n)
>> We could make the prototype of this function be:
>>
>> static void tcs_list_gen(struct list_head *bcm_list,
>>          struct tcs_cmd tcs_list[SDM845_MAX_VCD], int n[SDM845_MAX_VCD])
>>
>> which would catch errors if somebody later passed in an array that
>> wasn't the right size, since we blindly memset below.
> Yes, sounds good. I will try to optimize it.
>
> Thanks,
> Georgi
>
>>> +{
>>> +       struct qcom_icc_bcm *bcm;
>>> +       bool commit;
>>> +       size_t idx = 0, batch = 0, cur_vcd_size = 0;
>>> +
>>> +       memset(n, 0, sizeof(int) * SDM845_MAX_VCD);
>>> +
>>> +       list_for_each_entry(bcm, bcm_list, list) {
>>> +               commit = false;
>>> +               cur_vcd_size++;
>>> +               if ((list_is_last(&bcm->list, bcm_list)) ||
>>> +                   bcm->aux_data.vcd != list_next_entry(bcm, list)->aux_data.vcd) {
>>> +                       commit = true;
>>> +                       cur_vcd_size = 0;
>>> +               }
>>> +               tcs_cmd_gen(&tcs_list[idx], bcm->vote_x, bcm->vote_y,
>>> +                           bcm->addr, commit);
>>> +               idx++;
>>> +               n[batch]++;
>>> +               /*
>>> +                * Batch the BCMs in such a way that we do not split them in
>>> +                * multiple payloads when they are under the same VCD. This is
>>> +                * to ensure that every BCM is committed since we only set the
>>> +                * commit bit on the last BCM request of every VCD.
>>> +                */
>>> +               if (n[batch] >= MAX_RPMH_PAYLOAD) {
>>> +                       if (!commit) {
>>> +                               n[batch] -= cur_vcd_size;
>>> +                               n[batch + 1] = cur_vcd_size;
>>> +                       }
>>> +                       batch++;
>>> +               }
>>> +       }
>>> +}
>>> +

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