linux-kernel - Re: [PATCH] fbdev: radeon: Remove 'struct timeval' usage

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Date:	Wed, 3 Jun 2015 14:59:57 +0300
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Tina Ruchandani <ruchandani.tina@...il.com>,
	Arnd Bergmann <arnd@...db.de>
CC:	<y2038@...ts.linaro.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	<linux-fbdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fbdev: radeon: Remove 'struct timeval' usage



On 25/05/15 07:07, Tina Ruchandani wrote:
> 'struct timeval' uses a 32-bit representation for the
> seconds field which will overflow in the year 2038 and beyond.
> This patch replaces the usage of 'struct timeval' with
> ktime_t which uses a 64-bit time representation and does not
> suffer from the y2038 problem. This patch is part of a larger
> effort to remove all instances of 'struct timeval', 'struct
> timespec', time_t and other 32-bit timekeeping variables
> from the kernel.
> The patch also replaces the use of real time (do_gettimeofday)
> with monotonic time (ktime_get).
> 
> Signed-off-by: Tina Ruchandani <ruchandani.tina@...il.com>
> ---
>  drivers/video/fbdev/aty/radeon_base.c | 29 ++++++++++++++---------------
>  1 file changed, 14 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/video/fbdev/aty/radeon_base.c b/drivers/video/fbdev/aty/radeon_base.c
> index 01237c8..9747e9e 100644
> --- a/drivers/video/fbdev/aty/radeon_base.c
> +++ b/drivers/video/fbdev/aty/radeon_base.c
> @@ -64,6 +64,7 @@
>  #include <linux/slab.h>
>  #include <linux/delay.h>
>  #include <linux/time.h>
> +#include <linux/ktime.h>
>  #include <linux/fb.h>
>  #include <linux/ioport.h>
>  #include <linux/init.h>
> @@ -461,8 +462,8 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
>  	int hTotal, vTotal, num, denom, m, n;
>  	unsigned long long hz, vclk;
>  	long xtal;
> -	struct timeval start_tv, stop_tv;
> -	long total_secs, total_usecs;
> +	ktime_t start, stop;
> +	s64 delta;
>  	int i;
>  
>  	/* Ugh, we cut interrupts, bad bad bad, but we want some precision
> @@ -478,7 +479,7 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
>  		if (((INREG(CRTC_VLINE_CRNT_VLINE) >> 16) & 0x3ff) == 0)
>  			break;
>  
> -	do_gettimeofday(&start_tv);
> +	start = ktime_get();
>  
>  	for(i=0; i<1000000; i++)
>  		if (((INREG(CRTC_VLINE_CRNT_VLINE) >> 16) & 0x3ff) != 0)
> @@ -487,20 +488,18 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
>  	for(i=0; i<1000000; i++)
>  		if (((INREG(CRTC_VLINE_CRNT_VLINE) >> 16) & 0x3ff) == 0)
>  			break;
> -	
> -	do_gettimeofday(&stop_tv);
> -	
> +
> +	stop = ktime_get();
> +
>  	local_irq_enable();
>  
> -	total_secs = stop_tv.tv_sec - start_tv.tv_sec;
> -	if (total_secs > 10)
> +	delta = ktime_us_delta(stop, start);
> +
> +	/* Return -1 if more than 10 seconds have elapsed */
> +	if (delta > (10*1000000))
>  		return -1;
> -	total_usecs = stop_tv.tv_usec - start_tv.tv_usec;
> -	total_usecs += total_secs * 1000000;
> -	if (total_usecs < 0)
> -		total_usecs = -total_usecs;
> -	hz = 1000000/total_usecs;
> - 
> +	hz = 1000000/delta;
> +
>  	hTotal = ((INREG(CRTC_H_TOTAL_DISP) & 0x1ff) + 1) * 8;
>  	vTotal = ((INREG(CRTC_V_TOTAL_DISP) & 0x3ff) + 1);
>  	vclk = (long long)hTotal * (long long)vTotal * hz;
> @@ -548,7 +547,7 @@ static int radeon_probe_pll_params(struct radeonfb_info *rinfo)
>  		denom *= 3;
>  		break;
>  	case 6:
> -		denom *= 6;   
> +		denom *= 6;
>  		break;
>  	case 7:
>  		denom *= 12;

The above change was extra. I removed it, and queued this for 4.2.

 Tomi


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