linux-kernel - Re: [PATCH v2 05/10] drivers: qcom: rpmh-rsc: write sleep/wake requests to TCS

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Date:   Tue, 20 Feb 2018 16:03:40 +0000
From:   Lina Iyer <ilina@...eaurora.org>
To:     Evan Green <evgreen@...omium.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 05/10] drivers: qcom: rpmh-rsc: write sleep/wake
 requests to TCS

Hi Evan,

Thanks for your review.

On Fri, Feb 16 2018 at 23:51 +0000, Evan Green wrote:
>Hello Lina,
>
>On Thu, Feb 15, 2018 at 9:35 AM, Lina Iyer <ilina@...eaurora.org> wrote:
>> Sleep and wake requests are sent when the application processor
>> subsystem of the SoC is entering deep sleep states like in suspend.
>> These requests help lower the system power requirements when the
>> resources are not in use.
>>
>> Sleep and wake requests are written to the TCS slots but are not
>> triggered at the time of writing. The TCS are triggered by the firmware
>> after the last of the CPUs has executed its WFI. Since these requests
>> may come in different batches of requests, it is job of this controller
>> driver to find arrange the requests into the available TCSes.
>>
>> Signed-off-by: Lina Iyer <ilina@...eaurora.org>
>> ---
>>  drivers/soc/qcom/rpmh-internal.h |   7 +++
>>  drivers/soc/qcom/rpmh-rsc.c      | 126 +++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 133 insertions(+)
>>
>[...]
>> +static int find_slots(struct tcs_group *tcs, struct tcs_request *msg,
>> +                    int *m, int *n)
>> +{
>> +       int slot, offset;
>> +       int i = 0;
>> +
>> +       /* Find if we already have the msg in our TCS */
>> +       slot = find_match(tcs, msg->payload, msg->num_payload);
>> +       if (slot >= 0)
>> +               goto copy_data;
>> +
>> +       /* Do over, until we can fit the full payload in a TCS */
>> +       do {
>> +               slot = bitmap_find_next_zero_area(tcs->slots, MAX_TCS_SLOTS,
>> +                                                i, msg->num_payload, 0);
>> +               if (slot == MAX_TCS_SLOTS)
>> +                       break;
>> +               i += tcs->ncpt;
>> +       } while (slot + msg->num_payload - 1 >= i);
>> +
>> +       if (slot == MAX_TCS_SLOTS)
>> +               return -ENOMEM;
>> +
>> +copy_data:
>> +       bitmap_set(tcs->slots, slot, msg->num_payload);
>> +       /* Copy the addresses of the resources over to the slots */
>> +       for (i = 0; tcs->cmd_addr && i < msg->num_payload; i++)
>
>I don't think tcs->cmd_addr can be null, can it? Above, find_match()
>is already reaching through cmd_addr with enthusiasm. If kept, it
>could at least be moved outside of the loop.
>
It would be NULL for ACTIVE_TCS. I can move the check outside the loop.

Thanks,
Lina