[PATCH xf86-video-savage] Disable EXA acceleration for now

[Kevin Brace]

Hi Connor,

The code is broken, and that's why I disabled EXA.
I tested the code on Xubuntu 16.04.5 (X Server 1.19.6).
It can draw the initial login screen, but as soon as it gets past that, the screen will go black (not blank) and nothing happens.
The result is consistent across several S3 Savage cards (Savage IX, several Savage 4s, and Savage 2000) I tested.
Only disabling acceleration works around the bug.
Activating --disable-dri for the compilation script makes no difference, at least for the stock Linux 4.15 kernel Canonical ships with (Savage DRM is disabled).
The code might have a hard DRI1 dependency for the proper functioning of EXA.
I was thinking of releasing xf86-video-savage DDX Version 2.4 on Thursday.
If you can figure out what's wrong with the code, the fix can go for the hypothetical Version 2.5 sometime in the future.

Regards,

Kevin Brace
Brace Computer Laboratory blog
https://bracecomputerlab.com


> Date: Wed, 13 Feb 2019 14:03:02 -0500
> From: Connor Behan <connor.behan at gmail.com>
> To: xorg-devel at lists.x.org
> Subject: Re: [PATCH xf86-video-savage] Disable EXA acceleration for
> 	now
> Message-ID: <a805acf8-f8d8-2293-a796-c82683d2940e at gmail.com>
> Content-Type: text/plain; charset="utf-8"
> 
> On 2019-02-11 12:02 PM, Kevin Brace wrote:
> > EXA acceleration architecture code is currently broken on X Server
> > 1.19, so it should be disabled until it is fixed.
> >
> > Signed-off-by: Kevin Brace <kevinbrace at gmx.com>
> > ---
> >  src/savage_driver.c | 23 +++++++++++++++++++----
> >  1 file changed, 19 insertions(+), 4 deletions(-)
> Is this because the rendering is wrong? Or does the X server crash
> before you can test?
> > diff --git a/src/savage_driver.c b/src/savage_driver.c
> > index 01fc0bc..e26b0f1 100644
> > --- a/src/savage_driver.c
> > +++ b/src/savage_driver.c
> > @@ -1273,14 +1273,29 @@ static Bool SavagePreInit(ScrnInfoPtr pScrn, int flags)
> >  	        psav->useEXA = FALSE;
> >  	    } else if(!xf86NameCmp(strptr,"EXA")) {
> >  	       from = X_CONFIG;
> > -	       psav->useEXA = TRUE;
> > +	       psav->NoAccel = TRUE;
> > +	       psav->useEXA = FALSE;
> > +	       xf86DrvMsg(pScrn->scrnIndex, X_INFO,
> > +	                   "EXA acceleration architecture is "
> > +	                   "permanently disabled for this version.\n");
> >  	    }
> >          }
> >  #else
> > -	psav->useEXA = TRUE;
> > +	psav->NoAccel = TRUE;
> > +	psav->useEXA = FALSE;
> > +	xf86DrvMsg(pScrn->scrnIndex, X_INFO,
> > +	            "EXA acceleration architecture is "
> > +	            "permanently disabled for this version.\n");
> >  #endif
> > -       xf86DrvMsg(pScrn->scrnIndex, from, "Using %s acceleration architecture\n",
> > -		psav->useEXA ? "EXA" : "XAA");
> > +
> > +	if (!psav->NoAccel) {
> > +	    xf86DrvMsg(pScrn->scrnIndex, from,
> > +	                "Using %s acceleration architecture\n",
> > +	                psav->useEXA ? "EXA" : "XAA");
> > +	} else {
> > +	    xf86DrvMsg(pScrn->scrnIndex, X_INFO,
> > +	                "Hardware acceleration is disabled.\n");
> > +	}
> >      }
> >  
> >      if ((s = xf86GetOptValString(psav->Options, OPTION_OVERLAY))) {
> 
> 
> 
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