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

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Message-ID: <1581659590.12440.4.camel@mtksdaap41>
Date:   Fri, 14 Feb 2020 13:53:10 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Bibby Hsieh <bibby.hsieh@...iatek.com>
CC:     Jassi Brar <jassisinghbrar@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Herring <robh+dt@...nel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>,
        Nicolas Boichat <drinkcat@...omium.org>,
        Dennis-YC Hsieh <dennis-yc.hsieh@...iatek.com>,
        Houlong Wei <houlong.wei@...iatek.com>
Subject: Re: [PATCH 1/3] mailbox: mediatek: implement flush function

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@...iatek.com>
> ---
>  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,