linux-kernel - Re: [PATCH v3] staging: sm750fb: use arch_phys_wc_add() and ioremap

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Message-ID: <20150503192459.GA19486@kroah.com>
Date:	Sun, 3 May 2015 21:24:59 +0200
From:	Greg KH <gregkh@...uxfoundation.org>
To:	"Luis R. Rodriguez" <mcgrof@...not-panic.com>
Cc:	sudipm.mukherjee@...il.com, teddy.wang@...iconmotion.com,
	devel@...verdev.osuosl.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>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] staging: sm750fb: use arch_phys_wc_add() and
 ioremap_wc()

On Tue, Apr 21, 2015 at 01:12:03PM -0700, Luis R. Rodriguez wrote:
> From: "Luis R. Rodriguez" <mcgrof@...e.com>
> 
> The same area used for ioremap() is used for the MTRR area.
> Convert the driver from using the x86 specific MTRR code to
> the architecture agnostic arch_phys_wc_add(). arch_phys_wc_add()
> will avoid MTRR if write-combining is available, in order to
> take advantage of that also ensure the ioremap'd area is requested
> as write-combining.
> 
> There are a few motivations for this:
> 
> a) Take advantage of PAT when available
> 
> b) Help bury MTRR code away, MTRR is architecture specific and on
>    x86 its replaced by PAT
> 
> c) 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()")
> 
> The conversion done is expressed by the following Coccinelle
> SmPL patch, it additionally required manual intervention to
> address all the #ifdery and removal of redundant things which
> arch_phys_wc_add() already addresses such as verbose message
> about when MTRR fails and doing nothing when we didn't get
> an MTRR.
> 
> @ mtrr_found @
> expression index, base, size;
> @@
> 
> -index = mtrr_add(base, size, MTRR_TYPE_WRCOMB, 1);
> +index = arch_phys_wc_add(base, size);
> 
> @ mtrr_rm depends on mtrr_found @
> expression mtrr_found.index, mtrr_found.base, mtrr_found.size;
> @@
> 
> -mtrr_del(index, base, size);
> +arch_phys_wc_del(index);
> 
> @ mtrr_rm_zero_arg depends on mtrr_found @
> expression mtrr_found.index;
> @@
> 
> -mtrr_del(index, 0, 0);
> +arch_phys_wc_del(index);
> 
> @ mtrr_rm_fb_info depends on mtrr_found @
> struct fb_info *info;
> expression mtrr_found.index;
> @@
> 
> -mtrr_del(index, info->fix.smem_start, info->fix.smem_len);
> +arch_phys_wc_del(index);
> 
> @ ioremap_replace_nocache depends on mtrr_found @
> struct fb_info *info;
> expression base, size;
> @@
> 
> -info->screen_base = ioremap_nocache(base, size);
> +info->screen_base = ioremap_wc(base, size);
> 
> @ ioremap_replace_default depends on mtrr_found @
> struct fb_info *info;
> expression base, size;
> @@
> 
> -info->screen_base = ioremap(base, size);
> +info->screen_base = ioremap_wc(base, size);
> 
> Generated-by: Coccinelle SmPL
> Cc: Sudip Mukherjee <sudipm.mukherjee@...il.com>
> Cc: Teddy Wang <teddy.wang@...iconmotion.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> 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: devel@...verdev.osuosl.org
> Cc: linux-fbdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Luis R. Rodriguez <mcgrof@...e.com>
> ---
>  drivers/staging/sm750fb/sm750.c    | 36 ++++--------------------------------
>  drivers/staging/sm750fb/sm750.h    |  3 ---
>  drivers/staging/sm750fb/sm750_hw.c |  3 +--
>  3 files changed, 5 insertions(+), 37 deletions(-)

This doesn't apply to my staging-next branch :(
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