From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Smirl Subject: Re: Re: Who is stomping PCI config space? Date: Fri, 4 Mar 2005 12:35:20 -0500 Message-ID: <9e47339105030409352803c7e1@mail.gmail.com> References: <9e4733910503031103552514b9@mail.gmail.com> <1109891245.5611.246.camel@gaston> <9e473391050303161559c17955@mail.gmail.com> <9e47339105030319037f083f7@mail.gmail.com> <1109918459.5610.273.camel@gaston> <16936.20345.249542.65736@xf14.local> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.12] helo=sc8-sf-mx2.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1D7Gi3-00065J-Jh for linux-fbdev-devel@lists.sourceforge.net; Fri, 04 Mar 2005 09:35:31 -0800 Received: from rproxy.gmail.com ([64.233.170.203]) by sc8-sf-mx2.sourceforge.net with esmtp (Exim 4.41) id 1D7Gi2-0003Sg-4X for linux-fbdev-devel@lists.sourceforge.net; Fri, 04 Mar 2005 09:35:31 -0800 Received: by rproxy.gmail.com with SMTP id z35so1150605rne for ; Fri, 04 Mar 2005 09:35:29 -0800 (PST) In-Reply-To: <16936.20345.249542.65736@xf14.local> Sender: linux-fbdev-devel-admin@lists.sourceforge.net Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: Egbert Eich Cc: Benjamin Herrenschmidt , Xserver development , Linux Fbdev development list , Egbert Eich On Fri, 4 Mar 2005 13:02:34 +0100, Egbert Eich wrote: > you know well that we are not living in the same time zone, so you > may want to give me some time to answer. I was getting upset that when I did a VT switch my machine was hard locking and I had to keep rebooting all of the time to debug the problem. I had spent many hours trying to find the problem in my code and it wasn't there. I was not expecting X to alter the state of hardware it did not have a driver loaded for. > It needs to have it in some central place which doesn't necessarily > have to be the kernel. > The point is: if Jon needs these registers in an interrupt handler > he may have to tweak PCI config space form there anyway since another > card may currently have VGA routed. > > > > > X disables any other VGA card IO/MEM in the system so that at one given > > point in time, only one of them will decode VGA cycles. Wether it has > > those cards to drive in it's config or not doesn't matter, the problem > > at the bus level is the same. > > Right. It however should only do so if one of the cards it is driving > itself requires VGA registers for its mode of operation. Ok, now I see what X is doing. It is making sure there is only one active VGA device in the system. However, my framebuffer driver is not using VGA mode. I have similar code in my VGA support patch but I only shut down the card mem/io long enough to turn off VGA support. I don't leave the whole card turned off. I also see now that I should shut interrupts off while doing this. pci_read_config_word(pdev, PCI_COMMAND, &command); pci_write_config_word(pdev, PCI_COMMAND, command | PCI_COMMAND_IO | PCI_COMMAND_MEMORY); vga_io_w(0x3C3, ~0x01 & vga_io_r(0x3C3)); vga_io_w(0x46e8, ~0x08 & vga_io_r(0x46e8)); vga_io_w(0x102, ~0x01 & vga_io_r(0x102)); pci_write_config_word(pdev, PCI_COMMAND, command); If we leave the whole card turned off I can't access the interrupt status registers to acknowledge the interrupt and shut it off. Does this approach work for X? Where is the code that does this at VT switch time? On VT enter X would need to: 1) shut off interrupts 2) disable IO/MEM on all VGA cards - remember IO/mem state 3) turn the cards on one at a time and disable VGA - remember VGA enable state 4) restore IO/MEM state to all cards 5) turn interrupts back on On VT exit: 1) shut off interrupts 2) disable IO/MEM on all VGA cards - remember IO/mem state 3) restore VGA enable state 4) restore IO/MEM state to all cards 5) turn interrupts back on -- Jon Smirl jonsmirl@gmail.com ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click