Re: [PATCH 1/3] mailbox: mediatek: implement flush function

From: CK Hu
Date: Fri Feb 14 2020 - 00:53:18 EST


Hi, Bibby:

On Fri, 2020-02-14 at 12:33 +0800, Bibby Hsieh wrote:
> For client driver which need to reorganize the command buffer, it could
> use this function to flush the send command buffer.
> If the channel doesn't be started (usually in waiting for event), this
> function will abort it directly.
>
> Signed-off-by: Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx>
> ---
> drivers/mailbox/mtk-cmdq-mailbox.c | 50 ++++++++++++++++++++++++++++--
> 1 file changed, 48 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
> index 9a6ce9f5a7db..03e58ff62007 100644
> --- a/drivers/mailbox/mtk-cmdq-mailbox.c
> +++ b/drivers/mailbox/mtk-cmdq-mailbox.c
> @@ -5,6 +5,7 @@
> #include <linux/bitops.h>
> #include <linux/clk.h>
> #include <linux/clk-provider.h>
> +#include <linux/completion.h>

Why add this?

> #include <linux/dma-mapping.h>
> #include <linux/errno.h>
> #include <linux/interrupt.h>
> @@ -428,14 +429,59 @@ static int cmdq_mbox_startup(struct mbox_chan *chan)
> return 0;
> }
>
> -static void cmdq_mbox_shutdown(struct mbox_chan *chan)
> +static int cmdq_mbox_flush(struct mbox_chan *chan, unsigned long timeout)
> {
> + struct cmdq_thread *thread = (struct cmdq_thread *)chan->con_priv;
> + struct cmdq_task_cb *cb;
> + struct cmdq_cb_data data;
> + struct cmdq *cmdq = dev_get_drvdata(chan->mbox->dev);
> + struct cmdq_task *task, *tmp;
> + unsigned long flags;
> + u32 enable;
> +
> + spin_lock_irqsave(&thread->chan->lock, flags);
> + if (list_empty(&thread->task_busy_list))
> + goto out;
> +
> + WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> + if (!cmdq_thread_is_in_wfe(thread))
> + goto wait;
> +
> + list_for_each_entry_safe(task, tmp, &thread->task_busy_list,
> + list_entry) {
> + cb = &task->pkt->async_cb;
> + list_del(&task->list_entry);
> + kfree(task);
> + }
> +
> + if (cb->cb) {
> + data.sta = -ENOBUFS;

CMDQ_CB_ERROR?

I do not like cmdq to define itself error code, use standard error code
is better.

> + data.data = cb->data;
> + cb->cb(data);
> + }

Why just callback the latest packet? I think you should move this into
list_for_each_entry_safe{} loop.

> +
> + cmdq_thread_resume(thread);
> + cmdq_thread_disable(cmdq, thread);
> + clk_disable(cmdq->clock);
> +
> +out:
> + spin_unlock_irqrestore(&thread->chan->lock, flags);
> + return 0;
> +
> +wait:
> + cmdq_thread_resume(thread);
> + spin_unlock_irqrestore(&thread->chan->lock, flags);
> + if (readl_poll_timeout_atomic(thread->base + CMDQ_THR_ENABLE_TASK,
> + enable, enable == 0, 1, timeout))
> + dev_err(cmdq->mbox.dev, "Fail to wait GCE thread 0x%x done\n",
> + (u32)(thread->base - cmdq->base));

I think you should return error when timeout.

> + return 0;
> }
>
> static const struct mbox_chan_ops cmdq_mbox_chan_ops = {
> .send_data = cmdq_mbox_send_data,
> .startup = cmdq_mbox_startup,
> - .shutdown = cmdq_mbox_shutdown,

This patch is about flush function, why do you remove shutdown function?

Regards,
CK

> + .flush = cmdq_mbox_flush,
> };
>
> static struct mbox_chan *cmdq_xlate(struct mbox_controller *mbox,