linux-kernel - Re: [PATCH v2] mailbox: Hi3660: Fixup mailbox state machine malfunction issue

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Date:   Fri, 7 Dec 2018 14:14:27 +0800
From:   leo.yan@...aro.org
To:     Kevin Wangtao <kevin.wangtao@...ilicon.com>
Cc:     <jassisinghbrar@...il.com>, <linux-kernel@...r.kernel.org>,
        <gengyanping@...ilicon.com>, <suzhuangluan@...ilicon.com>,
        John Stultz <john.stultz@...aro.org>,
        Guodong Xu <guodong.xu@...aro.org>
Subject: Re: [PATCH v2] mailbox: Hi3660: Fixup mailbox state machine
 malfunction issue

On Mon, Dec 03, 2018 at 02:13:08PM +0800, Kevin Wangtao wrote:
> Current mailbox driver of Hi3660 release the mailbox directly
> before sending a new message which may cause last message lost
> and next message sending doesn't take effect actually.
> 
> This patch fixes this issue by following the right process below,
> each time before sending a message, mailbox driver will check
> whether the mailbox is in ready state, if last message has been
> acknowledged, mailbox driver will clear the ack state to turn
> the mailbox to ready state again.
> 
> Signed-off-by: Kevin Wangtao <kevin.wangtao@...ilicon.com>

Thanks for sending out this patch, Kevin.

I tested this patch at my side with two cases (one is dhry2 for
performance testing for every OPPs, and another is stress test
two clusters frequency change concurrently), both of them can
pass after applied this patch.

Reviewed-and-tested-by: Leo Yan <leo.yan@...aro.org>

Jassi, please review and pick it up if it's okay for you.

Thanks,
Leo Yan

> ---
> Changes v1 -> v2:
>  - update commit message
> 
>  drivers/mailbox/hi3660-mailbox.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c
> index 3eea6b6..035b71a 100644
> --- a/drivers/mailbox/hi3660-mailbox.c
> +++ b/drivers/mailbox/hi3660-mailbox.c
> @@ -38,6 +38,7 @@
>  #define MBOX_AUTOMATIC_ACK		1
>  
>  #define MBOX_STATE_IDLE			BIT(4)
> +#define MBOX_STATE_READY		BIT(5)
>  #define MBOX_STATE_ACK			BIT(7)
>  
>  #define MBOX_MSG_LEN			8
> @@ -91,8 +92,8 @@ static int hi3660_mbox_check_state(struct mbox_chan *chan)
>  	unsigned long val;
>  	unsigned int ret;
>  
> -	/* Mailbox is idle so directly bail out */
> -	if (readl(base + MBOX_MODE_REG) & MBOX_STATE_IDLE)
> +	/* Mailbox is ready to use */
> +	if (readl(base + MBOX_MODE_REG) & MBOX_STATE_READY)
>  		return 0;
>  
>  	/* Wait for acknowledge from remote */
> @@ -103,9 +104,9 @@ static int hi3660_mbox_check_state(struct mbox_chan *chan)
>  		return ret;
>  	}
>  
> -	/* Ensure channel is released */
> -	writel(0xffffffff, base + MBOX_IMASK_REG);
> -	writel(BIT(mchan->ack_irq), base + MBOX_SRC_REG);
> +	/* clear ack state, mailbox will get back to ready state */
> +	writel(BIT(mchan->ack_irq), base + MBOX_ICLR_REG);
> +
>  	return 0;
>  }
>  
> @@ -160,10 +161,6 @@ static int hi3660_mbox_startup(struct mbox_chan *chan)
>  {
>  	int ret;
>  
> -	ret = hi3660_mbox_check_state(chan);
> -	if (ret)
> -		return ret;
> -
>  	ret = hi3660_mbox_unlock(chan);
>  	if (ret)
>  		return ret;
> @@ -183,10 +180,11 @@ static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)
>  	void __iomem *base = MBOX_BASE(mbox, ch);
>  	u32 *buf = msg;
>  	unsigned int i;
> +	int ret;
>  
> -	/* Ensure channel is released */
> -	writel_relaxed(0xffffffff, base + MBOX_IMASK_REG);
> -	writel_relaxed(BIT(mchan->ack_irq), base + MBOX_SRC_REG);
> +	ret = hi3660_mbox_check_state(chan);
> +	if (ret)
> +		return ret;
>  
>  	/* Clear mask for destination interrupt */
>  	writel_relaxed(~BIT(mchan->dst_irq), base + MBOX_IMASK_REG);
> -- 
> 2.8.1
>