linux-kernel - Re: [PATCH v4 04/13] remoteproc: qcom: q6v5: Use qmp

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Date:   Wed, 21 Jul 2021 22:57:20 +0530
From:   Sibi Sankar <sibis@...eaurora.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     bjorn.andersson@...aro.org, mka@...omium.org, robh+dt@...nel.org,
        ulf.hansson@...aro.org, rjw@...ysocki.net, agross@...nel.org,
        ohad@...ery.com, mathieu.poirier@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dianders@...omium.org, rishabhb@...eaurora.org,
        sidgup@...eaurora.org
Subject: Re: [PATCH v4 04/13] remoteproc: qcom: q6v5: Use qmp_send to update
 co-processor load state

On 2021-07-21 10:56, Stephen Boyd wrote:
> Quoting Sibi Sankar (2021-07-19 21:36:38)
>> diff --git a/drivers/remoteproc/qcom_q6v5.c 
>> b/drivers/remoteproc/qcom_q6v5.c
>> index 7e9244c748da..997ff21271f7 100644
>> --- a/drivers/remoteproc/qcom_q6v5.c
>> +++ b/drivers/remoteproc/qcom_q6v5.c
>> @@ -16,8 +16,28 @@
>>  #include "qcom_common.h"
>>  #include "qcom_q6v5.h"
>> 
>> +#define Q6V5_LOAD_STATE_MSG_LEN        64
>>  #define Q6V5_PANIC_DELAY_MS    200
>> 
>> +static int q6v5_load_state_toggle(struct qcom_q6v5 *q6v5, bool 
>> enable)
>> +{
>> +       char buf[Q6V5_LOAD_STATE_MSG_LEN] = {};
> 
> Just to confirm, we want to set the whole buffer to zero before writing
> it? Sounds good to not send stack junk over to to the other side but
> maybe we could skip initializing to zero for the first part of the
> buffer that isn't used?

Sure, it makes sense to incorporate
a warn_on and memset the remainder
of the buffer after populating it.

> 
>> +       int ret;
>> +
>> +       if (IS_ERR(q6v5->qmp))
>> +               return 0;
>> +
>> +       snprintf(buf, sizeof(buf),
>> +                "{class: image, res: load_state, name: %s, val: %s}",
>> +                q6v5->load_state, enable ? "on" : "off");
> 
> Should we WARN_ON() if the message doesn't fit into the 64-bytes?
> 
>> +
>> +       ret = qmp_send(q6v5->qmp, buf, sizeof(buf));
>> +       if (ret)
>> +               dev_err(q6v5->dev, "failed to toggle load state\n");
>> +
>> +       return ret;
>> +}
>> +
>>  /**
>>   * qcom_q6v5_prepare() - reinitialize the qcom_q6v5 context before 
>> start
>>   * @q6v5:      reference to qcom_q6v5 context to be reinitialized
>> @@ -196,12 +223,13 @@ EXPORT_SYMBOL_GPL(qcom_q6v5_panic);
>>   * @pdev:      platform_device reference for acquiring resources
>>   * @rproc:     associated remoteproc instance
>>   * @crash_reason: SMEM id for crash reason string, or 0 if none
>> + * @load_state: load state resource string
>>   * @handover:  function to be called when proxy resources should be 
>> released
>>   *
>>   * Return: 0 on success, negative errno on failure
>>   */
>>  int qcom_q6v5_init(struct qcom_q6v5 *q6v5, struct platform_device 
>> *pdev,
>> -                  struct rproc *rproc, int crash_reason,
>> +                  struct rproc *rproc, int crash_reason, const char 
>> *load_state,
>>                    void (*handover)(struct qcom_q6v5 *q6v5))
>>  {
>>         int ret;
>> @@ -286,9 +314,36 @@ int qcom_q6v5_init(struct qcom_q6v5 *q6v5, struct 
>> platform_device *pdev,
>>                 return PTR_ERR(q6v5->state);
>>         }
>> 
>> +       q6v5->load_state = kstrdup_const(load_state, GFP_KERNEL);
>> +       q6v5->qmp = qmp_get(&pdev->dev);
>> +       if (IS_ERR(q6v5->qmp)) {
>> +               if (PTR_ERR(q6v5->qmp) != -ENODEV) {
>> +                       if (PTR_ERR(q6v5->qmp) != -EPROBE_DEFER)
>> +                               dev_err(&pdev->dev, "failed to acquire 
>> load state\n");
> 
> Use dev_err_probe()?

sure I'll use it.

> 
>> +                       kfree_const(q6v5->load_state);
>> +                       return PTR_ERR(q6v5->qmp);
>> +               }
>> +       } else {
>> +               if (!q6v5->load_state) {
> 
> Use else if and deindent?

lol, my bad.

> 
>> +                       dev_err(&pdev->dev, "load state resource 
>> string empty\n");
>> +                       return -EINVAL;
>> +               }
>> +       }
>> +
>>         return 0;
>>  }
>>  EXPORT_SYMBOL_GPL(qcom_q6v5_init);
>> 

-- 
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