linux-kernel - Re: [PATCH v3 16/17] video: fbdev: atmel_lcdfb: use ioremap

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Date:	Wed, 22 Apr 2015 09:34:02 +0200
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	"Luis R. Rodriguez" <mcgrof@...not-panic.com>,
	<plagnioj@...osoft.com>, <tomi.valkeinen@...com>
CC:	<linux-fbdev@...r.kernel.org>, <luto@...capital.net>,
	<cocci@...teme.lip6.fr>, "Luis R. Rodriguez" <mcgrof@...e.com>,
	Suresh Siddha <sbsiddha@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Juergen Gross <jgross@...e.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Dave Airlie <airlied@...hat.com>,
	Antonino Daplas <adaplas@...il.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 16/17] video: fbdev: atmel_lcdfb: use ioremap_wc()
 for framebuffer

Le 21/04/2015 22:16, Luis R. Rodriguez a écrit :
> From: "Luis R. Rodriguez" <mcgrof@...e.com>
> 
> The driver doesn't use mtrr_add() or arch_phys_wc_add() but
> since we know the framebuffer is isolated already on an
> ioremap() we can take advantage of write combining for
> performance where possible.
> 
> In this case there are a few motivations for this:
> 
> a) Take advantage of PAT when available
> 
> b) Help with the goal of eventually using _PAGE_CACHE_UC over
>    _PAGE_CACHE_UC_MINUS on x86 on ioremap_nocache() (see commit
>    de33c442e titled "x86 PAT: fix performance drop for glx,
>    use UC minus for ioremap(), ioremap_nocache() and
>    pci_mmap_page_range()")
> 
> Cc: Nicolas Ferre <nicolas.ferre@...el.com>

Seems okay:
Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>

Thanks for having taking care of atmel_lcdfb driver.
Bye,


> Cc: Suresh Siddha <sbsiddha@...il.com>
> Cc: Ingo Molnar <mingo@...e.hu>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Juergen Gross <jgross@...e.com>
> Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> Cc: Andy Lutomirski <luto@...capital.net>
> Cc: Dave Airlie <airlied@...hat.com>
> Cc: Antonino Daplas <adaplas@...il.com>
> Cc: Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>
> Cc: Tomi Valkeinen <tomi.valkeinen@...com>
> Cc: linux-fbdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Luis R. Rodriguez <mcgrof@...e.com>
> ---
>  drivers/video/fbdev/atmel_lcdfb.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/video/fbdev/atmel_lcdfb.c b/drivers/video/fbdev/atmel_lcdfb.c
> index 94a8d04..abadc49 100644
> --- a/drivers/video/fbdev/atmel_lcdfb.c
> +++ b/drivers/video/fbdev/atmel_lcdfb.c
> @@ -1266,7 +1266,8 @@ static int __init atmel_lcdfb_probe(struct platform_device *pdev)
>  			goto stop_clk;
>  		}
>  
> -		info->screen_base = ioremap(info->fix.smem_start, info->fix.smem_len);
> +		info->screen_base = ioremap_wc(info->fix.smem_start,
> +					       info->fix.smem_len);
>  		if (!info->screen_base) {
>  			ret = -ENOMEM;
>  			goto release_intmem;
> 


-- 
Nicolas Ferre
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