From: Jens Axboe <axboe@suse.de>
To: Alan Chandler <alan@chandlerfamily.org.uk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: ide-cd problem
Date: Mon, 22 Nov 2004 09:01:23 +0100 [thread overview]
Message-ID: <20041122080122.GM26240@suse.de> (raw)
In-Reply-To: <200411220752.28264.alan@chandlerfamily.org.uk>
On Mon, Nov 22 2004, Alan Chandler wrote:
> On Sunday 21 November 2004 16:13, Alan Chandler wrote:
> ...
> >
> > This seems to be some combination of frequently occuring timing problem,
> > and the difference treatment in cdrom_newpc_intr to cdrom_pc_intr
>
> I put a ndelay(400) at the head of cdrom_newpc_intr and the problem of
> DRQ being set when there was no data to transfer disappeared. It
> appears that my hardware is too slow.
>
> I have been reading the ATA/ATAPI - 6 spec, and it implies that the
> state of DRQ line need one pio cycle before being correct and that you
> should read the alternative status register to achieve this. I tried
> a simple
>
> HWIF(drive)->INB( IDE_ALTSTATUS_REG);
>
> But that made no difference.
ALTSTATUS read should be fine as well, but the implicit delay is
probably better.
Is this enough to fix it? For ->drq_interrupt we already should have
an adequate delay, Alan fixed this one recently.
===== drivers/ide/ide-cd.c 1.97 vs edited =====
--- 1.97/drivers/ide/ide-cd.c 2004-11-07 02:54:41 +01:00
+++ edited/drivers/ide/ide-cd.c 2004-11-22 08:58:15 +01:00
@@ -890,8 +890,13 @@
ide_execute_command(drive, WIN_PACKETCMD, handler, ATAPI_WAIT_PC, cdrom_timer_expiry);
return ide_started;
} else {
+ unsigned long flags;
+
/* packet command */
- HWIF(drive)->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
+ spin_lock_irqsave(&ide_lock, flags);
+ HWIF(drive)->OUTBSYNC(drive, WIN_PACKETCMD, IDE_COMMAND_REG);
+ ndelay(400);
+ spin_unlock_irqrestore(&ide_lock, flags);
return (*handler) (drive);
}
}
--
Jens Axboe
next prev parent reply other threads:[~2004-11-22 8:04 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-20 18:42 ide-cd problem Alan Chandler
2004-11-20 19:47 ` Jens Axboe
2004-11-21 0:53 ` Alan Chandler
2004-11-21 8:56 ` Jens Axboe
2004-11-21 10:25 ` Alan Chandler
2004-11-21 16:13 ` Alan Chandler
2004-11-22 7:52 ` Alan Chandler
2004-11-22 8:01 ` Jens Axboe [this message]
2004-11-22 10:30 ` Alan Chandler
2004-11-22 10:51 ` Jens Axboe
2004-11-22 11:29 ` Alan Chandler
2004-11-22 11:31 ` Jens Axboe
2004-11-22 12:53 ` Alan Chandler
2004-11-22 13:02 ` Jens Axboe
2004-11-22 19:19 ` Alan Chandler
2004-11-22 23:48 ` Alan Chandler
2004-11-23 7:13 ` Alan Chandler
2004-11-23 14:51 ` Jens Axboe
2004-11-23 21:49 ` Alan Chandler
2004-11-26 23:39 ` Alan Chandler
2004-11-29 17:29 ` Bill Davidsen
2004-11-30 8:59 ` Alan Chandler
2004-12-10 21:32 ` ide-cd problem revisited - more brainpower needed Alan Chandler
2004-12-10 23:14 ` Alan Cox
2004-12-12 0:17 ` Alan Chandler
2004-12-12 11:39 ` Alan Cox
2004-12-12 13:34 ` Alan Chandler
2004-12-14 0:20 ` Alan Chandler
2004-12-16 15:56 ` Bill Davidsen
2004-12-17 23:59 ` Alan Chandler
2004-11-24 23:19 ` ide-cd problem Alan Cox
2004-11-25 15:29 ` Jens Axboe
2004-11-25 16:25 ` Alan Cox
2004-11-25 18:12 ` Jens Axboe
2004-11-25 18:45 ` Alan Chandler
2004-11-23 18:34 ` Jeff Garzik
2004-11-23 19:13 ` Jens Axboe
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