Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261178AbULAAjl (ORCPT ); Tue, 30 Nov 2004 19:39:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261218AbULAAg0 (ORCPT ); Tue, 30 Nov 2004 19:36:26 -0500 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:21683 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S261232AbULAA1I (ORCPT ); Tue, 30 Nov 2004 19:27:08 -0500 Date: Tue, 30 Nov 2004 09:29:47 -0200 From: Marcelo Tosatti To: Geert Uytterhoeven Cc: vince@arm.linux.org.uk, Linux Kernel Development , Linux Frame Buffer Device Development Subject: Re: Linux 2.4.29-pre1 (was: Re: [PATCH] vga16fb: Fix frame buffer bad memory mapping) Message-ID: <20041130112947.GB3041@dmt.cyclades> References: <200411252301.iAPN1mo4023046@hera.kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3611 Lines: 81 On Sat, Nov 27, 2004 at 04:54:12PM +0100, Geert Uytterhoeven wrote: > On Thu, 25 Nov 2004, Linux Kernel Mailing List wrote: > > ChangeSet 1.1543, 2004/11/25 13:16:49-02:00, vince@arm.linux.org.uk > > > > [PATCH] vga16fb: Fix frame buffer bad memory mapping > > > > The vga16fb driver uses a direct ioremap on 0xa00000 to gain access to > > the vga card. This is wrong on architectures other than x86, every > > other driver uses VGA_MAP_MEM macro from vga.h to ensure the correct > > memory mapping. > > > > All this patch does is add the mapping macro this has been tested and > > works on ARM systems The driver no longer maps parts of kernel > > workspace and modifies it. > > This fix is not correct! > > > diff -Nru a/drivers/video/vga16fb.c b/drivers/video/vga16fb.c > > --- a/drivers/video/vga16fb.c 2004-11-25 15:01:51 -08:00 > > +++ b/drivers/video/vga16fb.c 2004-11-25 15:01:51 -08:00 > > @@ -142,7 +142,7 @@ > > memset(fix, 0, sizeof(struct fb_fix_screeninfo)); > > strcpy(fix->id,"VGA16 VGA"); > > > > - fix->smem_start = VGA_FB_PHYS; > > + fix->smem_start = VGA_MAP_MEM(VGA_FB_PHYS); > > fix->smem_len = VGA_FB_PHYS_LEN; > > fix->type = FB_TYPE_VGA_PLANES; > > fix->visual = FB_VISUAL_PSEUDOCOLOR; > > fix->smem_start: Although I agree VGA_FB_PHYS is not the correct value on > machines other than PC, VGA_MAP_MEM(VGA_FB_PHYS) is not appropriate either, > because fix->smem_start is supposed to be a CPU _physical_ address, not a > virtual address. > > However, this value isn't really used, except by (very rare) userspace that > wants to mmap the frame buffer through /dev/mem instead of /dev/fb*, so an > incorrect value doesn't really harm. > > > @@ -896,7 +896,7 @@ > > > > /* XXX share VGA_FB_PHYS region with vgacon */ > > > > - vga16fb.video_vbase = ioremap(VGA_FB_PHYS, VGA_FB_PHYS_LEN); > > + vga16fb.video_vbase = ioremap(VGA_MAP_MEM(VGA_FB_PHYS), VGA_FB_PHYS_LEN); > > if (!vga16fb.video_vbase) { > > printk(KERN_ERR "vga16fb: unable to map device\n"); > > return -ENOMEM; > > ioremap(): VGA_MAP_MEM() already a _virtual_ address: > > | include/asm-alpha/vga.h:#define VGA_MAP_MEM(x) ((unsigned long) ioremap((x), 0)) > | include/asm-arm/vga.h:#define VGA_MAP_MEM(x) (PCIMEM_BASE + (x)) > | include/asm-i386/vga.h:#define VGA_MAP_MEM(x) (unsigned long)phys_to_virt(x) > | include/asm-ia64/vga.h:#define VGA_MAP_MEM(x) ((unsigned long) ioremap((x), 0)) > | include/asm-mips/vga.h:#define VGA_MAP_MEM(x) ((unsigned long)0xb0000000 + (unsigned long)(x)) > | include/asm-ppc/vga.h:#define VGA_MAP_MEM(x) (x + vgacon_remap_base) > | include/asm-ppc64/vga.h:#define VGA_MAP_MEM(x) ((unsigned long) ioremap((x), 0)) > | include/asm-sparc64/vga.h:#define VGA_MAP_MEM(x) (x) > | include/asm-x86_64/vga.h:#define VGA_MAP_MEM(x) (unsigned long)phys_to_virt(x) > > Doing a double ioremap(), or ioremap(phys_to_virt()) will break for sure... > > BTW, on (PReP/CHRP) PPC ioremap() on ISA memory space `just works' because > __ioremap() adds _ISA_MEM_BASE to the passed pointer if it's smaller than > 16*1024*1024. And yes, vga16fb used to work fine on my CHRP LongTrail > (before the machine itself died :-(. > > Yes, ISA memory space is a mess to do right in a portable way... Geert, I'll guest I'll just revert the whole change then... Do you have a better suggestion? Thanks! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/