Re: ide-cd problem

[Jens Axboe]

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

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