Re: [PATCH] spi: limit reaches -1, tested 0

[David Brownell <david-b@pacbell.net>]

On Sunday 08 February 2009, Roel Kluin wrote:
> >>> -			while ((read(drv_data) == 0) && limit--);
> >>> +			while ((read(drv_data) == 0) && --limit);
> > 
> > ... although I wouldn't have resisted the urge to make the
> > loop body be "cpu_relax();" instead of an empty statement.
> 
> Ok,
> ---------------------------->8-------------------8<-----------------------------
> With a postfix decrement limit will reach -1 rather than 0, so the warning will
> not be issued.
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>

Still:

Acked-by: David Brownell <dbrownell@users.sourceforge.net>


> ---
> diff --git a/drivers/spi/spi_imx.c b/drivers/spi/spi_imx.c
> index 269a55e..15abe61 100644
> --- a/drivers/spi/spi_imx.c
> +++ b/drivers/spi/spi_imx.c
> @@ -779,7 +779,8 @@ static irqreturn_t interrupt_transfer(struct driver_data *drv_data)
>  
>  			/* Read trailing bytes */
>  			limit = loops_per_jiffy << 1;
> -			while ((read(drv_data) == 0) && limit--);
> +			while ((read(drv_data) == 0) && limit--)
> +				cpu_relax();
>  
>  			if (limit == 0)
>  				dev_err(&drv_data->pdev->dev,
> 
>