Re: [PATCH v3] staging: sm750fb: use arch_phys_wc_add() and ioremap_wc()

[Luis R. Rodriguez]

On Sun, May 03, 2015 at 09:24:59PM +0200, Greg KH wrote:
> On Tue, Apr 21, 2015 at 01:12:03PM -0700, Luis R. Rodriguez wrote:
> > From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>
> > 
> > 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@xxxxxxxxx>
> > Cc: Teddy Wang <teddy.wang@xxxxxxxxxxxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Suresh Siddha <sbsiddha@xxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Juergen Gross <jgross@xxxxxxxx>
> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> > Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> > Cc: Dave Airlie <airlied@xxxxxxxxxx>
> > Cc: Antonino Daplas <adaplas@xxxxxxxxx>
> > Cc: Jean-Christophe Plagniol-Villard <plagnioj@xxxxxxxxxxxx>
> > Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> > Cc: devel@xxxxxxxxxxxxxxxxxxxx
> > Cc: linux-fbdev@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
> > ---
> >  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 :(

OK I'll resend a v4 now.

  Luis
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