Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 13 Mar 2002 15:50:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 13 Mar 2002 15:49:54 -0500 Received: from chaos.analogic.com ([204.178.40.224]:59011 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Wed, 13 Mar 2002 15:49:45 -0500 Date: Wed, 13 Mar 2002 15:49:45 -0500 (EST) From: "Richard B. Johnson" Reply-To: root@chaos.analogic.com To: =?ISO-8859-1?Q?Romain_Li=E9vin?= cc: Alan Cox , Kernel List Subject: Re: your mail In-Reply-To: <1016051318.3c8fb67699ae8@imp.free.fr> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 13 Mar 2002, [ISO-8859-1] Romain Li?vin wrote: I'm going to comment on a few points: [SNIPPED most...] > + > +/* D-bus protocol: > + 1 0 0 > + _______ ______|______ __________|________ __________ > +Red : ________ | ____ | ____ > + _ ____________|________ ______|__________ _____ > +White: ________ | ______ | _______ > +*/ > + > +/* Try to transmit a byte on the specified port (-1 if error). */ > +static int put_ti_parallel(int minor, unsigned char data) > +{ > + int bit, i; > + unsigned long max; > + > + for (bit=0; bit<8; bit++) { > + if (data & 1) { > + outbyte(2, minor); > + START(max); > + do { > + WAIT(max); > + } while (inbyte(minor) & 0x10); This may never happen. You end up waiting forever! If the port doesn't exist or is broken, it may return 0xff forever! You need to time-out and get out. > + > + outbyte(3, minor); > + START(max); > + do { > + WAIT(max); > + } while (!(inbyte(minor) & 0x10)); This may never happen. You end up awiting forever! You need to time-out and get out. > + } else { > + outbyte(1, minor); > + START(max); > + do { > + WAIT(max); > + } while (inbyte(minor) & 0x20); > + This also may never happen! Same applies, time-out and get out. > + outbyte(3, minor); > + START(max); > + do { > + WAIT(max); > + } while (!(inbyte(minor) & 0x20)); This also may never happen! Same applives, time-out and get out. > + } > + data >>= 1; > + for(i=0; i < delay; i++) { > + inbyte(minor); > + } > + schedule(); This will just spin without setting current->policy |= SCHED_YIELD; (you really should use sys_sched_yield()) > + } > + > + return 0; > +} > + > +/* Receive a byte on the specified port or -1 if error. */ > +static int get_ti_parallel(int minor) > +{ > + int bit,i; > + unsigned char v, data=0; > + unsigned long max; > + > + for (bit=0; bit<8; bit++) { > + START(max); > + do { > + WAIT(max); > + } while ((v=inbyte(minor) & 0x30) == 0x30); > + More wait-forever above... > + if (v == 0x10) { > + data=(data>>1) | 0x80; > + outbyte(1, minor); > + START(max); > + do { > + WAIT(max); > + } while (!(inbyte(minor) & 0x20)); More wait-forever above. > + outbyte(3, minor); > + } else { > + data=data>>1; > + outbyte(2, minor); > + START(max); > + do { > + WAIT(max); > + } while (!(inbyte(minor) & 0x10)); > + outbyte(3, minor); More wait-forever! > + } > + for(i=0; i + inbyte(minor); > + } > + schedule(); No current->policy > + } > + return (int)data; > +} > + [SNIPPED rest] Basically, this code performs a needed function. I have been waiting for someone to write this! However, it's not yet ready for prime-time. Never assume that hardware is going to produce what you expect. Don't wait forever for something that was supposed to happen. You'll hang the machine. Cheers, Dick Johnson Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips). Windows-2000/Professional isn't. - 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/