linux-kernel - Re: [PATCH v10 10/10] drivers: qcom: rpmh-rsc: allow active requests from wake TCS

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Date:   Wed, 13 Jun 2018 14:09:52 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Raju P L S S S N <rplsssn@...eaurora.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        linux-arm-msm@...r.kernel.org,
        "open list:ARM/QUALCOMM SUPPORT" <linux-soc@...r.kernel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Evan Green <evgreen@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Lina Iyer <ilina@...eaurora.org>
Subject: Re: [PATCH v10 10/10] drivers: qcom: rpmh-rsc: allow active requests
 from wake TCS

Hi,

On Mon, Jun 11, 2018 at 10:25 AM, Raju P L S S S N
<rplsssn@...eaurora.org> wrote:
> @@ -148,7 +148,8 @@ int rpmh_rsc_invalidate(struct rsc_drv *drv)
>  static struct tcs_group *get_tcs_for_msg(struct rsc_drv *drv,
>                                          const struct tcs_request *msg)
>  {
> -       int type;
> +       int type, ret;
> +       struct tcs_group *tcs;
>
>         switch (msg->state) {
>         case RPMH_ACTIVE_ONLY_STATE:
> @@ -164,7 +165,25 @@ static struct tcs_group *get_tcs_for_msg(struct rsc_drv *drv,
>                 return ERR_PTR(-EINVAL);
>         }
>
> -       return get_tcs_of_type(drv, type);
> +       /*
> +        * If we are making an active request on a RSC that does not have a
> +        * dedicated TCS for active state use, then re-purpose a wake TCS to
> +        * send active votes.
> +        * NOTE: The driver must be aware that this RSC does not have a
> +        * dedicated AMC, and therefore would invalidate the sleep and wake
> +        * TCSes before making an active state request.
> +        */
> +       tcs = get_tcs_of_type(drv, type);
> +       if (msg->state == RPMH_ACTIVE_ONLY_STATE && IS_ERR(tcs)) {
> +               tcs = get_tcs_of_type(drv, WAKE_TCS);
> +               if (!IS_ERR(tcs)) {
> +                       ret = rpmh_rsc_invalidate(drv);
> +                       if (ret)
> +                               return ERR_PTR(ret);

In v9 you looped as long as the "ret" was -EAGAIN.  Now you're not.
Are all the callers setup to handle -EAGAIN or should you keep the
loop in for -EAGAIN?  I don't think callers handle this well.

...or is there some reason that EAGAIN can't happen in this call to
rpmh_rsc_invalidate()?


-Doug