linux-kernel - Re: [PATCH] soc: qcom: aoss: Read back before triggering the IRQ

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Date:   Tue, 11 Feb 2020 22:32:14 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Arun Kumar Neelakantam <aneela@...eaurora.org>
Cc:     clew@...eaurora.org, Andy Gross <agross@...nel.org>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] soc: qcom: aoss: Read back before triggering the IRQ

On Wed 22 Jan 00:24 PST 2020, Arun Kumar Neelakantam wrote:

> In some device memory used by msm_qmp, there can be an early ack of a
> write to memory succeeding. This may cause the outgoing interrupt to be
> triggered before the msgram reflects the write.
> 
> Add a readback to ensure the data is flushed to device memory before
> triggering the ipc interrupt.
> 
> Signed-off-by: Arun Kumar Neelakantam <aneela@...eaurora.org>

Applied

Thanks,
Bjorn

> ---
>  drivers/soc/qcom/qcom_aoss.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c
> index fe79661..f43a2e0 100644
> --- a/drivers/soc/qcom/qcom_aoss.c
> +++ b/drivers/soc/qcom/qcom_aoss.c
> @@ -225,6 +225,7 @@ static bool qmp_message_empty(struct qmp *qmp)
>  static int qmp_send(struct qmp *qmp, const void *data, size_t len)
>  {
>  	long time_left;
> +	size_t tlen;
>  	int ret;
>  
>  	if (WARN_ON(len + sizeof(u32) > qmp->size))
> @@ -239,6 +240,9 @@ static int qmp_send(struct qmp *qmp, const void *data, size_t len)
>  	__iowrite32_copy(qmp->msgram + qmp->offset + sizeof(u32),
>  			 data, len / sizeof(u32));
>  	writel(len, qmp->msgram + qmp->offset);
> +
> +	/* Read back len to confirm data written in message RAM */
> +	tlen = readl(qmp->msgram + qmp->offset);
>  	qmp_kick(qmp);
>  
>  	time_left = wait_event_interruptible_timeout(qmp->event,
> -- 
> 1.9.1