Re: [XFree86] vgaHWLock(), vgaHWUnlock()

2003-02-25 Thread Dr Andrew C Aitchison 
On Mon, 24 Feb 2003, Marc Aurele La France wrote:

 On 24 Feb 2003, Nat Ersoz wrote:
 
  While tracking down a bug, I encoutered these functions in:
  programs/Xserver/hw/xfree86/vgahw/vgaHW.c:
 
  void vgaHWLock(vgaHWPtr hwp)
  {
  /* Protect CRTC[0-7] */
  hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11)  ~0x80);
  }
 
  void vgaHWUnlock(vgaHWPtr hwp)
  {
  /* Unprotect CRTC[0-7] */
   hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11) | 0x80);
  }
 
  Every reference I can find on the sbuject, (specifically Ferraro's book,
  3rd ed, along with many HTML references) indicate that this logic is
  reversed.  That is, for CRTC reg 0x11 bit 7: 1=disable, 0=enable writing
  to CRTC regs[0-7].
 
  Comments?
 
 You are absolutely correct.  I've just committed a change to correct this.
 Thanks for pointing out the problem.

Is it safe to do that this close to a release ?
There could be bugs that didn't get a chance to do anything because
the hardware was locked.

-- 
Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge
[EMAIL PROTECTED]   http://www.dpmms.cam.ac.uk/~werdna

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Re: [XFree86] vgaHWLock(), vgaHWUnlock()

2003-02-25 Thread Mark Vojkovich 
On Tue, 25 Feb 2003, David Dawes wrote:

 On Mon, Feb 24, 2003 at 02:30:25PM -0700, Marc Aurele La France wrote:
 On 24 Feb 2003, Nat Ersoz wrote:
 
  While tracking down a bug, I encoutered these functions in:
  programs/Xserver/hw/xfree86/vgahw/vgaHW.c:
 
  void vgaHWLock(vgaHWPtr hwp)
  {
  /* Protect CRTC[0-7] */
  hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11)  ~0x80);
  }
 
  void vgaHWUnlock(vgaHWPtr hwp)
  {
  /* Unprotect CRTC[0-7] */
   hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11) | 0x80);
  }
 
  Every reference I can find on the sbuject, (specifically Ferraro's book,
  3rd ed, along with many HTML references) indicate that this logic is
  reversed.  That is, for CRTC reg 0x11 bit 7: 1=disable, 0=enable writing
  to CRTC regs[0-7].
 
  Comments?
 
 You are absolutely correct.  I've just committed a change to correct this.
 Thanks for pointing out the problem.
 
 I wonder why this hasn't shown up as a problem anywhere?
 

   The nv driver doesn't use these.  It provides its own which 
has the reverse logic from what vgaHW was using.


Mark.


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Re: [XFree86] vgaHWLock(), vgaHWUnlock()

2003-02-25 Thread Marc Aurele La France 
On Tue, 25 Feb 2003, Mark Vojkovich wrote:

   While tracking down a bug, I encoutered these functions in:
   programs/Xserver/hw/xfree86/vgahw/vgaHW.c:

   void vgaHWLock(vgaHWPtr hwp)
   {
   /* Protect CRTC[0-7] */
   hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11)  ~0x80);
   }

   void vgaHWUnlock(vgaHWPtr hwp)
   {
   /* Unprotect CRTC[0-7] */
hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11) | 0x80);
   }

   Every reference I can find on the sbuject, (specifically Ferraro's book,
   3rd ed, along with many HTML references) indicate that this logic is
   reversed.  That is, for CRTC reg 0x11 bit 7: 1=disable, 0=enable writing
   to CRTC regs[0-7].

   Comments?

  You are absolutely correct.  I've just committed a change to correct this.
  Thanks for pointing out the problem.

  I wonder why this hasn't shown up as a problem anywhere?

The nv driver doesn't use these.  It provides its own which
 has the reverse logic from what vgaHW was using.

Well, the bit doesn't affect reading the registers.  As for writes,
vgaHWRestoreMode(), which many drivers end up calling to set a mode,
ensures the bit is off before re-writting the CRTC registers.

Marc.

+--+---+
|  Marc Aurele La France   |  work:   1-780-492-9310   |
|  Computing and Network Services  |  fax:1-780-492-1729   |
|  352 General Services Building   |  email:  [EMAIL PROTECTED]  |
|  University of Alberta   +---+
|  Edmonton, Alberta   |   |
|  T6G 2H1 | Standard disclaimers apply|
|  CANADA  |   |
+--+---+
XFree86 Core Team member.  ATI driver and X server internals.

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Re: [XFree86] vgaHWLock(), vgaHWUnlock()

2003-02-24 Thread Marc Aurele La France 
On 24 Feb 2003, Nat Ersoz wrote:

 While tracking down a bug, I encoutered these functions in:
 programs/Xserver/hw/xfree86/vgahw/vgaHW.c:

 void vgaHWLock(vgaHWPtr hwp)
 {
 /* Protect CRTC[0-7] */
 hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11)  ~0x80);
 }

 void vgaHWUnlock(vgaHWPtr hwp)
 {
 /* Unprotect CRTC[0-7] */
  hwp-writeCrtc(hwp, 0x11, hwp-readCrtc(hwp, 0x11) | 0x80);
 }

 Every reference I can find on the sbuject, (specifically Ferraro's book,
 3rd ed, along with many HTML references) indicate that this logic is
 reversed.  That is, for CRTC reg 0x11 bit 7: 1=disable, 0=enable writing
 to CRTC regs[0-7].

 Comments?

You are absolutely correct.  I've just committed a change to correct this.
Thanks for pointing out the problem.

Marc.

+--+---+
|  Marc Aurele La France   |  work:   1-780-492-9310   |
|  Computing and Network Services  |  fax:1-780-492-1729   |
|  352 General Services Building   |  email:  [EMAIL PROTECTED]  |
|  University of Alberta   +---+
|  Edmonton, Alberta   |   |
|  T6G 2H1 | Standard disclaimers apply|
|  CANADA  |   |
+--+---+
XFree86 Core Team member.  ATI driver and X server internals.

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