linux-kernel - Re: [PATCH 5/7] agp/nvidia: Ignore value returned by readl()

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Message-ID: <25f8e66c-09e8-f5d8-e3d5-ec48fbd8287d@gmx.de>
Date:   Tue, 30 Nov 2021 11:13:52 +0100
From:   Helge Deller <deller@....de>
To:     Thomas Zimmermann <tzimmermann@...e.de>, airlied@...ux.ie,
        daniel.vetter@...ll.ch, arnd@...db.de, gregkh@...uxfoundation.org,
        James.Bottomley@...senPartnership.com
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] agp/nvidia: Ignore value returned by readl()

On 11/12/21 15:16, Thomas Zimmermann wrote:
> Fix the compiler warning
>
>   drivers/char/agp/nvidia-agp.c: In function 'nvidia_tlbflush':
>   drivers/char/agp/nvidia-agp.c:264:22: warning: variable 'temp' set but not used [-Wunused-but-set-variable]
>     264 |         u32 wbc_reg, temp;
>
> by removing the unused variable. The affected readl() is only
> required for flushing caches, but the returned value is not of
> interest.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
> ---
>  drivers/char/agp/nvidia-agp.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/agp/nvidia-agp.c b/drivers/char/agp/nvidia-agp.c
> index f78e756157db..437b3581cbe5 100644
> --- a/drivers/char/agp/nvidia-agp.c
> +++ b/drivers/char/agp/nvidia-agp.c
> @@ -261,7 +261,7 @@ static int nvidia_remove_memory(struct agp_memory *mem, off_t pg_start, int type
>  static void nvidia_tlbflush(struct agp_memory *mem)
>  {
>  	unsigned long end;
> -	u32 wbc_reg, temp;
> +	u32 wbc_reg;
>  	int i;
>
>  	/* flush chipset */
> @@ -283,9 +283,9 @@ static void nvidia_tlbflush(struct agp_memory *mem)
>
>  	/* flush TLB entries */
>  	for (i = 0; i < 32 + 1; i++)
> -		temp = readl(nvidia_private.aperture+(i * PAGE_SIZE / sizeof(u32)));
> +		(void)readl(nvidia_private.aperture+(i * PAGE_SIZE / sizeof(u32)));

IMHO the void is ugly.
Would tagging temp with "__maybe_unused" work ?

Helge


>  	for (i = 0; i < 32 + 1; i++)
> -		temp = readl(nvidia_private.aperture+(i * PAGE_SIZE / sizeof(u32)));
> +		(void)readl(nvidia_private.aperture+(i * PAGE_SIZE / sizeof(u32)));
>  }
>
>
>