linux-kernel - Re: [PATCH 1/4] remoteproc: qcom: q6v5-mss: Use regmap_read_poll

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Date:   Mon, 20 Jan 2020 11:24:32 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     evgreen@...omium.org, p.zabel@...gutronix.de, ohad@...ery.com,
        linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, agross@...nel.org
Subject: Re: [PATCH 1/4] remoteproc: qcom: q6v5-mss: Use
 regmap_read_poll_timeout

On Fri 17 Jan 05:51 PST 2020, Sibi Sankar wrote:

> Replace the loop for HALT_ACK detection with regmap_read_poll_timeout.
> 

Nice, but we should be able to do the same in q6v5proc_halt_axi_port()?

> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> ---
>  drivers/remoteproc/qcom_q6v5_mss.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index 51f451311f5fc..f20b39c6ff0ed 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -73,6 +73,7 @@
>  #define NAV_AXI_IDLE_BIT		BIT(2)
>  
>  #define HALT_ACK_TIMEOUT_MS		100
> +#define NAV_HALT_ACK_TIMEOUT_US		200
>  
>  /* QDSP6SS_RESET */
>  #define Q6SS_STOP_CORE			BIT(0)
> @@ -746,7 +747,6 @@ static void q6v5proc_halt_nav_axi_port(struct q6v5 *qproc,
>  				       struct regmap *halt_map,
>  				       u32 offset)
>  {
> -	unsigned long timeout;
>  	unsigned int val;
>  	int ret;
>  
> @@ -760,15 +760,11 @@ static void q6v5proc_halt_nav_axi_port(struct q6v5 *qproc,
>  			   NAV_AXI_HALTREQ_BIT);
>  
>  	/* Wait for halt ack*/
> -	timeout = jiffies + msecs_to_jiffies(HALT_ACK_TIMEOUT_MS);
> -	for (;;) {
> -		ret = regmap_read(halt_map, offset, &val);
> -		if (ret || (val & NAV_AXI_HALTACK_BIT) ||
> -		    time_after(jiffies, timeout))
> -			break;
> -
> -		udelay(5);
> -	}
> +	ret = regmap_read_poll_timeout(halt_map, offset, val,
> +				       (val & NAV_AXI_HALTACK_BIT),
> +				       5, NAV_HALT_ACK_TIMEOUT_US);
> +	if (ret)
> +		dev_err(qproc->dev, "nav halt ack timeout\n");

Is there a case where this new print adds value beyond the printout we
already have for the case of IDLE_BIT not going high? Can we simply
ignore the return value and skip the print?

Regards,
Bjorn

>  
>  	ret = regmap_read(halt_map, offset, &val);
>  	if (ret || !(val & NAV_AXI_IDLE_BIT))
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project