linux-kernel - Re: [PATCH v8 10/10] drivers: qcom: rpmh-rsc: allow active requests from wake TCS

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Date:   Fri, 11 May 2018 13:17:34 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Lina Iyer <ilina@...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>, rplsssn@...eaurora.org
Subject: Re: [PATCH v8 10/10] drivers: qcom: rpmh-rsc: allow active requests
 from wake TCS

Hi,

On Wed, May 9, 2018 at 10:01 AM, Lina Iyer <ilina@...eaurora.org> wrote:
> Some RSCs may only have sleep and wake TCS, i.e, there is no dedicated
> TCS for active mode request, but drivers may still want to make active
> requests from these RSCs. In such cases re-purpose the wake TCS to send
> active state requests.
>
> The requirement for this is that the driver is aware that the wake TCS
> is being repurposed to send active request, hence the sleep and wake
> TCSes be invalidated before the active request is sent.
>
> Signed-off-by: Lina Iyer <ilina@...eaurora.org>
> Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>  drivers/soc/qcom/rpmh-rsc.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
> index 68c25ebbbe09..369b9b3eedc5 100644
> --- a/drivers/soc/qcom/rpmh-rsc.c
> +++ b/drivers/soc/qcom/rpmh-rsc.c
> @@ -153,6 +153,7 @@ static struct tcs_group *get_tcs_for_msg(struct rsc_drv *drv,
>                                          const struct tcs_request *msg)
>  {
>         int type;
> +       struct tcs_group *tcs;
>
>         switch (msg->state) {
>         case RPMH_ACTIVE_ONLY_STATE:
> @@ -168,7 +169,22 @@ 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))
> +                       rpmh_rsc_invalidate(drv);

I noticed that rpmh_rsc_invalidate() can return -EAGAIN.  Do you need
to deal with that here?


-Doug