Re: [PATCH 3/9] ide: move IRQ clearing from ack_intr() method to clear_irq() method

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

On Friday 12 June 2009 20:24:58 Sergei Shtylyov wrote:
> Hello.
> 
> Bartlomiej Zolnierkiewicz wrote:
> 
> >> There are now two methods that clear the port interrupt: ack_intr() method,
> >> implemented only on M680x0 machines, that is called at the start of ide_intr(),
> >> and clear_irq() method, that is called somewhat later in this function.  In
> >> order to stop this duplication, delegate the task of clearing the interrupt
> >> to clear_irq() method, only leaving to ack_intr() the task of testing for the
> >> port interrupt.  This involves moving clear_irq() method call in ide_intr()
> >> closer to the beginning of the function and removing ack_intr() method call
> >> in ide_timer_expiry(), now becoming useless...
> >>
> >> Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
> >>
> >> ---
> >> The patch is atop of ide-2.6.git 'for-next' branch.
> >>
> >>  drivers/ide/gayle.c  |   23 +++++++++++------------
> >>  drivers/ide/ide-io.c |   11 ++++-------
> >>  drivers/ide/macide.c |   18 ++++++++++++++----
> >>  3 files changed, 29 insertions(+), 23 deletions(-)
> >>
> >> Index: ide-2.6/drivers/ide/gayle.c
> >> ===================================================================
> >> --- ide-2.6.orig/drivers/ide/gayle.c
> >> +++ ide-2.6/drivers/ide/gayle.c
> >> @@ -66,7 +66,7 @@ MODULE_PARM_DESC(doubler, "enable suppor
> >>       *  Check and acknowledge the interrupt status
> >>       */
> >>  
> >> -static int gayle_ack_intr_a4000(ide_hwif_t *hwif)
> >> +static int gayle_ack_intr(ide_hwif_t *hwif)
> >>  {
> >>      unsigned char ch;
> >>  
> >> @@ -76,16 +76,12 @@ static int gayle_ack_intr_a4000(ide_hwif
> >>      return 1;
> >>  }
> >>  
> >> -static int gayle_ack_intr_a1200(ide_hwif_t *hwif)
> >> +static void gayle_a1200_clear_irq(ide_drive_t *drive)
> >>  {
> >> -    unsigned char ch;
> >> +    ide_hwif_t *hwif = drive->hwif;
> >>  
> >> -    ch = z_readb(hwif->io_ports.irq_addr);
> >> -    if (!(ch & GAYLE_IRQ_IDE))
> >> -	return 0;
> >>      (void)z_readb(hwif->io_ports.status_addr);
> >>      z_writeb(0x7c, hwif->io_ports.irq_addr);
> >> -    return 1;
> >>  }
> >>     
> >
> > buddha.c needs a similar treatment
> >   
> 
>    Do you mean this fragment of xsurf_ack_intr()?

Yes.

>     /* X-Surf needs a 0 written to IRQ register to ensure ISA bit A11 stays at 0 */
>     z_writeb(0, hwif->io_ports.irq_addr);
> 
> 
>    I felt doubtful about it and decided to leave it as is.
> 
> >> --- ide-2.6.orig/drivers/ide/ide-io.c
> >> +++ ide-2.6/drivers/ide/ide-io.c
> >>     
> >
> >   
> >> @@ -791,6 +789,10 @@ irqreturn_t ide_intr (int irq, void *dev
> >>  		goto out;
> >>  
> >>  	handler = hwif->handler;
> >> +	drive	= hwif->cur_dev;
> >> +
> >> +	if (hwif->port_ops && hwif->port_ops->clear_irq)
> >> +		hwif->port_ops->clear_irq(drive);
> >>     
> >
> > We need to check for valid ->handler before using ->cur_dev
> > (it may contain a stale value otherwise).
> >   
> 
>    Hm...
> 
> > Moreover I somehow miss the point of moving ->clear_irq call here
> >   
> 
>    I moved it here because ack_intr() was clearing the interrupt at 
> exactly *this* point.

ack_intr() is a m68k-specific thing -- please take a look at things from
this perspective.

> > (it should be done after we know that it is really our IRQ).
> >   
> 
>    I don't think that really matters much...

We can have ->clear_irq without ->test_irq (i.e. piix) and thus end up
incorrectly clearing IRQ in case of shared IRQs..