Re: [PATCH 3/6] mailbox: Add support for ST's Mailbox IP

Alexey Klimov
2015-07-23T17:23:32Z

Hi Lee,

On Fri, Jul 17, 2015 at 3:04 PM, Lee Jones <lee.jones@linaro.org> wrote:
> ST's platforms currently support a maximum of 5 Mailboxes, one for
> each of the supported co-processors situated on the platform. Each
> Mailbox is divided up into 4 instances which consist of 32 channels.
> Messages are passed between the application and co-processors using
> shared memory areas. It is the Client's responsibility to manage
> these areas.
>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
> drivers/mailbox/Kconfig | 7 +
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/mailbox-sti.c | 562 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 571 insertions(+)
> create mode 100644 drivers/mailbox/mailbox-sti.c

[..]

> +static irqreturn_t sti_mbox_thread_handler(int irq, void *data)
> +{
> + struct sti_mbox_device *mdev = data;
> + struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
> + struct mbox_chan *chan;
> + unsigned int instance;
> +
> + for (instance = 0; instance < pdata->num_inst; instance++) {
> +keep_looking:
> + chan = sti_mbox_irq_to_channel(mdev, instance);
> + if (!chan)
> + continue;
> +
> + mbox_chan_received_data(chan, NULL);
> + sti_mbox_clear_irq(chan);
> + sti_mbox_enable_channel(chan);
> + goto keep_looking;
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t sti_mbox_irq_handler(int irq, void *data)
> +{
> + struct sti_mbox_device *mdev = data;
> + struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
> + struct sti_channel *chan_info;
> + struct mbox_chan *chan;
> + unsigned int instance;
> + int ret = IRQ_NONE;
> +
> + for (instance = 0; instance < pdata->num_inst; instance++) {
> + chan = sti_mbox_irq_to_channel(mdev, instance);
> + if (!chan)
> + continue;
> + chan_info = chan->con_priv;
> +
> + if (!sti_mbox_channel_is_enabled(chan)) {
> + dev_warn(mdev->dev,
> + "Unexpected IRQ: %s\n"
> + " instance: %d: channel: %d [enabled: %x]\n",
> + mdev->name, chan_info->instance,
> + chan_info->channel, mdev->enabled[instance]);
> + ret = IRQ_HANDLED;
> + continue;
> + }
> +
> + sti_mbox_disable_channel(chan);
> + ret = IRQ_WAKE_THREAD;
> + }
> +
> + if (ret == IRQ_NONE)
> + dev_err(mdev->dev, "Spurious IRQ - was a channel requested?\n");
> +
> + return ret;
> +}

With such usage of ret variable can it happen that handling of last
but one channel/instance will set ret to IRQ_WAKE_THREAD and at the
same time handling of last channel/instance will set ret to
IRQ_HANDLED during iteration loop and finally generic subsystem will
not wake up thread handler because it will receive IRQ_HANDLED?
Just checking.

[..]

--
Thanks,
Alexey Klimov