netdev - Re: [E1000-devel] [PATCH] i40e: Fix 32 bit shift compilation warnings

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Message-ID: <20130831094509.5211b0d1@nehalam.linuxnetplumber.net>
Date:	Sat, 31 Aug 2013 09:45:09 -0700
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	e1000-devel@...ts.sourceforge.net,
	Bruce Allan <bruce.w.allan@...el.com>,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	linux-kernel@...r.kernel.org,
	John Ronciak <john.ronciak@...el.com>, netdev@...r.kernel.org
Subject: Re: [E1000-devel] [PATCH] i40e: Fix 32 bit shift compilation
 warnings

On Fri, 30 Aug 2013 18:47:35 -0700
Joe Perches <joe@...ches.com> wrote:

> When dma_addr_t is a 32 bit value, >> 32 emits compiler warnings
> Use ((addr>>16) >>16) to avoid this.
> 
> I presume the macro should actually use the kernel.h
> macro upper_32_bits() eventually.
> 
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_hmc.h  | 2 +-
>  drivers/net/ethernet/intel/i40e/i40e_type.h | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_hmc.h b/drivers/net/ethernet/intel/i40e/i40e_hmc.h
> index 745fb355..2f1b72f 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_hmc.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e_hmc.h
> @@ -123,7 +123,7 @@ struct i40e_hmc_info {
>  #define I40E_SET_PF_SD_ENTRY(hw, pa, sd_index, type)			\
>  {									\
>  	u32 val1, val2, val3;						\
> -	val1 = (u32)((pa) >> sizeof(u32) * 8);				\
> +	val1 = (u32)(I40E_HI_DWORD(pa));				\
>  	val2 = (u32)(pa) | (I40E_HMC_MAX_BP_COUNT <<			\
>  		 I40E_PFHMC_SDDATALOW_PMSDBPCOUNT_SHIFT) |		\
>  		((((type) == I40E_SD_TYPE_PAGED) ? 0 : 1) <<		\
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_type.h b/drivers/net/ethernet/intel/i40e/i40e_type.h
> index 36e35cc..4263cf7 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_type.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e_type.h
> @@ -78,8 +78,8 @@ typedef void (*I40E_ADMINQ_CALLBACK)(struct i40e_hw *, struct i40e_aq_desc *);
>  #define I40E_ETH_LENGTH_OF_ADDRESS	6
>  
>  /* Data type manipulation macros. */
> -#define I40E_HI_DWORD(x)	((u32)(((x)>>32)&0xFFFFFFFF))
> -#define I40E_LO_DWORD(x)	((u32)((x)&0xFFFFFFFF))
> +#define I40E_HI_DWORD(x)	((u32)((((x) >> 16) >> 16) & 0xFFFFFFFF))
> +#define I40E_LO_DWORD(x)	((u32)((x) & 0xFFFFFFFF))
>  
>  #define I40E_HI_WORD(x)		((u16)(((x)>>16)&0xFFFF))
>  #define I40E_DESC_UNUSED(R)	\

After seeing this before in other drivers, a standard set of macros
was added called upper_32bits and lower_32bits. These should be used instead
of masking.

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