From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Maciej W. Rozycki" Date: Sat, 12 Oct 2013 13:08:52 +0000 Subject: Re: [PATCH 2/2] framebuffer: Remove pmag-aa-fb Message-Id: List-Id: References: <6f500d88eb23fd9a4cfc5583f5ca17bc5f58fe24.1379641901.git.joe@perches.com> <1379702587.2301.12.camel@joe-AO722> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Joe Perches Cc: Geert Uytterhoeven , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Linux Fbdev development list , "linux-kernel@vger.kernel.org" , Linux MIPS Mailing List Joe, Just a quick update. On Sun, 22 Sep 2013, Maciej W. Rozycki wrote: > As to the PMAG-AA board itself -- well, this is indeed a very rare item,= =20 > but I happen to have a specimen. To support it properly I'll first have = > to wire it to a monitor somehow though; signalling is standard, 1.0 Vpp=20 > composite monochrome, but what looks to me like a type F connector is use= d=20 > for video output, quite unusually for a graphics card (and for DEC itself= =20 > too as 3W3 was their usual video socket). It looks to me like converting= =20 > it to BNC and then a standard DE-15 VGA connector (via the green line)=20 > will be the easiest way to get image produced by the adapter on a=20 > contemporary monitor (sync-on-green required of course, but with LCD=20 > devices being the norm now that seems less of a problem these days). So more weirdly even that's actually a TNC connector rather than a type F = one. I've got a suitable TNC->BNC adapter now (although regrettably such=20 adapters seem to be available as 50=D9 parts only; hopefully any distortion= =20 won't be too significant or maybe my digital monitor will even be able to=20 compensate it, but at =A31.76 (~$2.64) per item it's certainly worth trying= =20 before resorting to the original DEC TNC->BNC cable still apparently=20 available from second-hand part suppliers at ~=A380/$120 per a mere 1ft=20 part) and a BNC->DE-15 cable is on the way. > > --- a/drivers/video/pmag-aa-fb.c > > +++ b/drivers/video/pmag-aa-fb.c > > @@ -459,7 +459,7 @@ static int __init init_one(int slot) > > return -EINVAL; > > =20 > > printk(KERN_INFO "fb%d: %s frame buffer in TC slot %d\n", > > - GET_FB_IDX(ip->info.node), ip->info.modename, slot); > > + ip->info.node, ip->info.modename, slot); > > =20 > > return 0; > > } >=20 > Thanks, but the changes required are actually much more than that -- the= =20 > driver has never been converted to the modern TURBOchannel API. I have=20 > now dug out an old patch I was working on back in 2006 to convert this=20 > driver as well as drivers/video/maxinefb.c. I'll try to complete the two= =20 > drivers as soon as possible (unfortunately I can't test the latter at all= ;=20 > it's for an onboard graphics adapter of another DECstation model),=20 > although I now remember the main reason I didn't complete them back then = > was they used an old internal API that was removed and no suitable=20 > replacement provided. I need to investigate again what that actually was= =20 > though (hw cursor probably). So I think I've got all the basic stuff covered now, including a change=20 similar to your proposal as well as a conversion to the driver model/new=20 TURBOchannel support infrastructure. But what I remembered is actually=20 right, the issue is wiring hardware cursor support into fbcon. The driver = uses its own display_switch structure with its own aafbcon_cursor handler=20 to use the twin onboard Bt431 chips for cursor generation (there's also=20 aafbcon_set_font that pokes at the Bt431s for cursor dimension changes). =20 I need to figure out what the best way will be to make the fbcon subsystem = support such an arrangement and that'll take me a little bit yet, so=20 please be patient. Note that the board is weird enough to have a 1-bit (true monochrome)=20 graphics plane, however the Bt455 used by the MX graphics adapter for=20 screen image generation is a 4-bit grey-scale video RAMDAC (only the LSB=20 inputs of its pixel port are wired to the graphics plane) and the twin=20 Bt431s use the overlay plane to produce a 2-bit grey-scale cursor. So we=20 do want to use the hardware cursor to be able to make it prominent among=20 the characters displayed throughout the screen and a software-generated=20 cursor cannot really substitute what hardware provides. Maciej