linux-kernel - Re: [PATCH 4/4] mailbox: arm_mhu: Add ARM MHU doorbell driver

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Message-ID: <CABb+yY11d8uS34yfE6-c_NP6n5pmxvmjs67aOKEAduhUpnU3Uw@mail.gmail.com>
Date:   Fri, 2 Oct 2020 14:42:37 -0500
From:   Jassi Brar <jassisinghbrar@...il.com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Jassi Brar <jaswinder.singh@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        ALKML <linux-arm-kernel@...ts.infradead.org>,
        DTML <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Frank Rowand <frowand.list@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh@...nel.org>, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 4/4] mailbox: arm_mhu: Add ARM MHU doorbell driver

On Mon, Sep 28, 2020 at 6:45 AM Sudeep Holla <sudeep.holla@....com> wrote:

> +
> +static void mhu_db_shutdown(struct mbox_chan *chan)
> +{
> +       struct mhu_db_channel *chan_info = chan->con_priv;
> +       struct mbox_controller *mbox = &chan_info->mhu->mbox;
> +       int i;
> +
> +       for (i = 0; i < mbox->num_chans; i++)
> +               if (chan == &mbox->chans[i])
> +                       break;
> +
> +       if (mbox->num_chans == i) {
> +               dev_warn(mbox->dev, "Request to free non-existent channel\n");
> +               return;
> +       }
> +
> +       /* Reset channel */
> +       mhu_db_mbox_clear_irq(chan);
> +       chan->con_priv = NULL;
>
request->free->request will fail because of this NULL assignment.
Maybe add a 'taken' flag in mhu_db_channel, which should also be
checked before calling mbox_chan_received_data because the data may
arrive for a now relinquished channel.

> +
> +static struct mbox_chan *mhu_db_mbox_xlate(struct mbox_controller *mbox,
> +                                          const struct of_phandle_args *spec)
> +{
> +       struct arm_mhu *mhu = dev_get_drvdata(mbox->dev);
> +       struct mhu_db_channel *chan_info;
> +       struct mbox_chan *chan = NULL;
> +       unsigned int pchan = spec->args[0];
> +       unsigned int doorbell = spec->args[1];
> +       int i;
> +
> +       /* Bounds checking */
> +       if (pchan >= MHU_CHANS || doorbell >= MHU_NUM_DOORBELLS) {
> +               dev_err(mbox->dev,
> +                       "Invalid channel requested pchan: %d doorbell: %d\n",
> +                       pchan, doorbell);
> +               return ERR_PTR(-EINVAL);
> +       }
> +
> +       for (i = 0; i < mbox->num_chans; i++) {
> +               chan_info = mbox->chans[i].con_priv;
> +
> +               /* Is requested channel free? */
> +               if (chan_info &&
> +                   mbox->dev == chan_info->mhu->dev &&
> +                   pchan == chan_info->pchan &&
> +                   doorbell == chan_info->doorbell) {
> +                       dev_err(mbox->dev, "Channel in use\n");
> +                       return ERR_PTR(-EBUSY);
> +               }
> +
You may want to reuse mhu_db_mbox_to_channel.