From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752563AbbC1AVy (ORCPT ); Fri, 27 Mar 2015 20:21:54 -0400 Received: from cantor2.suse.de ([195.135.220.15]:36958 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751745AbbC1AVw (ORCPT ); Fri, 27 Mar 2015 20:21:52 -0400 Date: Sat, 28 Mar 2015 01:21:48 +0100 From: "Luis R. Rodriguez" To: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , Andy Lutomirski , Bjorn Helgaas , "Luis R. Rodriguez" , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Juergen Gross , Jan Beulich , Borislav Petkov , Suresh Siddha , venkatesh.pallipadi@intel.com, Dave Airlie , "linux-kernel@vger.kernel.org" , Linux Fbdev development list , X86 ML , "xen-devel@lists.xenproject.org" , Ingo Molnar , Linus Torvalds , Daniel Vetter , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen Subject: Re: [PATCH v1 09/47] vidoe: fbdev: atyfb: remove and fix MTRR MMIO "hole" work around Message-ID: <20150328002148.GS5622@wotan.suse.de> References: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> <1426893517-2511-10-git-send-email-mcgrof@do-not-panic.com> <20150321091514.GA22926@sci.fi> <20150327193813.GH5622@wotan.suse.de> <20150327195759.GK5622@wotan.suse.de> <20150327215655.GA29933@sci.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20150327215655.GA29933@sci.fi> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 27, 2015 at 11:56:55PM +0200, Ville Syrjälä wrote: > On Fri, Mar 27, 2015 at 08:57:59PM +0100, Luis R. Rodriguez wrote: > > On Fri, Mar 27, 2015 at 12:43:55PM -0700, Andy Lutomirski wrote: > > > On Fri, Mar 27, 2015 at 12:38 PM, Luis R. Rodriguez wrote: > > > > On Sat, Mar 21, 2015 at 11:15:14AM +0200, Ville Syrjälä wrote: > > > >> On Fri, Mar 20, 2015 at 04:17:59PM -0700, Luis R. Rodriguez wrote: > > > >> > diff --git a/drivers/video/fbdev/aty/atyfb_base.c b/drivers/video/fbdev/aty/atyfb_base.c > > > >> > index 8025624..8875e56 100644 > > > >> > --- a/drivers/video/fbdev/aty/atyfb_base.c > > > >> > +++ b/drivers/video/fbdev/aty/atyfb_base.c > > > >> > @@ -2630,21 +2630,10 @@ static int aty_init(struct fb_info *info) > > > >> > > > > >> > #ifdef CONFIG_MTRR > > > >> > par->mtrr_aper = -1; > > > >> > - par->mtrr_reg = -1; > > > >> > if (!nomtrr) { > > > >> > - /* Cover the whole resource. */ > > > >> > - par->mtrr_aper = mtrr_add(par->res_start, par->res_size, > > > >> > + par->mtrr_aper = mtrr_add(info->fix.smem_start, > > > >> > + info->fix.smem_len, > > > >> > MTRR_TYPE_WRCOMB, 1); > > > >> > > > >> MTRRs need power of two size, so how is this supposed to work? > > > > > > > > As per mtrr_add_page() [0] the base and size are just supposed to be in units > > > > of 4 KiB, although the practice is to use powers of 2 in *some* drivers this > > > > is not standardized and by no means recorded as a requirement. Obviously > > > > powers of 2 will work too and you'd end up neatly aligned as well. mtrr_add() > > > > will use mtrr_check() to verify the the same requirement. Furthermore, > > > > as per my commit log message: > > > > > > Whatever the code may or may not do, the x86 architecture uses > > > power-of-two MTRR sizes. So I'm confused. > > > > There should be no confusion, I simply did not know that *was* the > > requirement for x86, if that is the case we should add a check for that > > and perhaps generalize a helper that does the power of two helper changes, > > the cleanest I found was the vesafb driver solution. > > > > Thoughts? > > The vesafb solution is bad since you'll only end up covering only > the first 4MB of the framebuffer instead of the almost 8MB you want. OK so the power of 2 requirement implicates us *having* to use a large MTRR that includes the MMIo region in the shared PCI case? Andy, Ville, are we 100% certain about this power of two requirement? Is that for the base and size or just the size? Luis From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luis R. Rodriguez" Date: Sat, 28 Mar 2015 00:21:48 +0000 Subject: Re: [PATCH v1 09/47] vidoe: fbdev: atyfb: remove and fix MTRR MMIO "hole" work around Message-Id: <20150328002148.GS5622@wotan.suse.de> List-Id: References: <1426893517-2511-1-git-send-email-mcgrof@do-not-panic.com> <1426893517-2511-10-git-send-email-mcgrof@do-not-panic.com> <20150321091514.GA22926@sci.fi> <20150327193813.GH5622@wotan.suse.de> <20150327195759.GK5622@wotan.suse.de> <20150327215655.GA29933@sci.fi> In-Reply-To: <20150327215655.GA29933@sci.fi> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , Andy Lutomirski , Bjorn Helgaas , "Luis R. Rodriguez" , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Juergen Gross , Jan Beulich , Borislav Petkov , Suresh Siddha , venkatesh.pallipadi@intel.com, Dave Airlie , "linux-kernel@vger.kernel.org" , Linux Fbdev development list , X86 ML , "xen-devel@lists.xenproject.org" , Ingo Molnar , Linus Torvalds , Daniel Vetter , Antonino Daplas , Jean-Christophe Plagniol-Villard , Tomi Valkeinen On Fri, Mar 27, 2015 at 11:56:55PM +0200, Ville Syrj=E4l=E4 wrote: > On Fri, Mar 27, 2015 at 08:57:59PM +0100, Luis R. Rodriguez wrote: > > On Fri, Mar 27, 2015 at 12:43:55PM -0700, Andy Lutomirski wrote: > > > On Fri, Mar 27, 2015 at 12:38 PM, Luis R. Rodriguez = wrote: > > > > On Sat, Mar 21, 2015 at 11:15:14AM +0200, Ville Syrj=E4l=E4 wrote: > > > >> On Fri, Mar 20, 2015 at 04:17:59PM -0700, Luis R. Rodriguez wrote: > > > >> > diff --git a/drivers/video/fbdev/aty/atyfb_base.c b/drivers/vide= o/fbdev/aty/atyfb_base.c > > > >> > index 8025624..8875e56 100644 > > > >> > --- a/drivers/video/fbdev/aty/atyfb_base.c > > > >> > +++ b/drivers/video/fbdev/aty/atyfb_base.c > > > >> > @@ -2630,21 +2630,10 @@ static int aty_init(struct fb_info *info) > > > >> > > > > >> > #ifdef CONFIG_MTRR > > > >> > par->mtrr_aper =3D -1; > > > >> > - par->mtrr_reg =3D -1; > > > >> > if (!nomtrr) { > > > >> > - /* Cover the whole resource. */ > > > >> > - par->mtrr_aper =3D mtrr_add(par->res_start, par->res= _size, > > > >> > + par->mtrr_aper =3D mtrr_add(info->fix.smem_start, > > > >> > + info->fix.smem_len, > > > >> > MTRR_TYPE_WRCOMB, 1); > > > >> > > > >> MTRRs need power of two size, so how is this supposed to work? > > > > > > > > As per mtrr_add_page() [0] the base and size are just supposed to b= e in units > > > > of 4 KiB, although the practice is to use powers of 2 in *some* dri= vers this > > > > is not standardized and by no means recorded as a requirement. Obvi= ously > > > > powers of 2 will work too and you'd end up neatly aligned as well. = mtrr_add() > > > > will use mtrr_check() to verify the the same requirement. Furthermo= re, > > > > as per my commit log message: > > >=20 > > > Whatever the code may or may not do, the x86 architecture uses > > > power-of-two MTRR sizes. So I'm confused. > >=20 > > There should be no confusion, I simply did not know that *was* the > > requirement for x86, if that is the case we should add a check for that > > and perhaps generalize a helper that does the power of two helper chang= es, > > the cleanest I found was the vesafb driver solution. > >=20 > > Thoughts? >=20 > The vesafb solution is bad since you'll only end up covering only > the first 4MB of the framebuffer instead of the almost 8MB you want. OK so the power of 2 requirement implicates us *having* to use a large MTRR that includes the MMIo region in the shared PCI case? Andy, Ville, are we 100% certain about this power of two requirement? Is that for the base and size or just the size? Luis