linux-kernel - Re: [PATCH 1/8] memory: emif: Correct the lpmode timeout calculation

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Date:	Mon, 11 Mar 2013 11:04:02 +0530
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Lokesh Vutla <lokeshvutla@...com>
CC:	<linux-kernel@...r.kernel.org>, <gregkh@...uxfoundation.org>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/8] memory: emif: Correct the lpmode timeout calculation

minor nit.
$subject
s/Correct/Fix

On Monday 11 March 2013 10:35 AM, Lokesh Vutla wrote:
> The driver tries to round up the specified timeout cycles to
> the next power of 2 value. But this is done wrongly.
> Correcting this here.
>
Change needs to be improved here. See below.
 
> Reported-by: Nishanth Menon <nm@...com>
> Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
> ---
>  drivers/memory/emif.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/memory/emif.c b/drivers/memory/emif.c
> index df08736..622638c 100644
> --- a/drivers/memory/emif.c
> +++ b/drivers/memory/emif.c
> @@ -732,9 +732,9 @@ static u32 get_pwr_mgmt_ctrl(u32 freq, struct emif_data *emif, u32 ip_rev)
>  	if (timeout < 16) {
>  		timeout = 0;
>  	} else {
> -		timeout = __fls(timeout) - 3;
>  		if (timeout & (timeout - 1))
So from the change, it appears that, the timeout
check for power of 2 should be done before updating
the variable which seems to be the right fix.

> -			timeout++;
> +			timeout <<= 1;
> +		timeout = __fls(timeout) - 3;
>  	}
>  
>  	switch (lpmode) {
> 
So just make changelog verbose as well as add a
comment about the calculation in the code.

Otherwise, patch looks fine to me.
Acked-by: Santosh Shilimkar <santosh.shilimkar@...com>
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