linux-kernel - Re: [PATCH] staging: nvec: Fix usleep

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Date:   Wed, 29 Nov 2017 18:07:53 +0200
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Joshua Abraham <j.abraham1776@...il.com>, marvin24@....de
Cc:     gregkh@...uxfoundation.org, ac100@...ts.launchpad.net,
        linux-tegra@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: nvec: Fix usleep_range is preferred over udelay

On 11/29/2017 06:00 PM, Joshua Abraham wrote:
> Signed-off-by: Joshua Abraham <j.abraham1776@...il.com>
> 
> This patch fixes the issue:
> 
> CHECK: usleep_range is preferred over udelay; see
> Documentation/timers/timers-howto.txt
> 
> ---
>   drivers/staging/nvec/nvec.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/nvec/nvec.c b/drivers/staging/nvec/nvec.c
> index 4ff8f47385da..2a01ef4b54ff 100644
> --- a/drivers/staging/nvec/nvec.c
> +++ b/drivers/staging/nvec/nvec.c
> @@ -631,7 +631,7 @@ static irqreturn_t nvec_interrupt(int irq, void *dev)
>   		break;
>   	case 2:		/* first byte after command */
>   		if (status == (I2C_SL_IRQ | RNW | RCVD)) {
> -			udelay(33);
> +			usleep_range(30, 35);
>   			if (nvec->rx->data[0] != 0x01) {
>   				dev_err(nvec->dev,
>   					"Read without prior read command\n");
> 

This is incorrect, as this function is an interrupt handler and we 
cannot sleep in interrupt context.

Cheers,
Mikko