AACI broken with commit 29a4f2d3

[catalin.marinas@arm.com (Catalin Marinas)]

On Fri, 2010-03-26 at 14:00 +0000, Philby John wrote:
> On 03/26/2010 07:24 PM, Catalin Marinas wrote:
> > On Fri, 2010-03-26 at 13:10 +0000, Philby John wrote:
> >> On 03/26/2010 06:30 PM, Catalin Marinas wrote:
> >>> On Fri, 2010-03-26 at 11:28 +0000, Philby John wrote:
> >>>> --- a/sound/arm/aaci.c
> >>>> +++ b/sound/arm/aaci.c
> >>>> @@ -863,7 +863,11 @@ static int __devinit aaci_probe_ac97(struct aaci *aaci)
> >>>>           struct snd_ac97 *ac97;
> >>>>           int ret;
> >>>>
> >>>> -       writel(0, aaci->base + AC97_POWERDOWN);
> >>>> +       /*
> >>>> +        * Fix: ac97 read back fail errors by reading
> >>>> +        * from Power down register
> >>>> +        */
> >>>> +       readw(aaci->base + 0x26);
> >>>
> >>> I still don't understand this. Does aaci->base point to the AACI
> >>> registers? There is no register at offset 0x26 but there is one at 0x24
> >>> (32-bit AACIIE2).
> >>>
> >>
> >> I think there is a register at 0x26 for AACI, except that its not
> >> defined in aaci.h. References in the manual such as "The AC-link signals
> >> can be placed in low-power mode, when the power down control
> >> and status register (0x26) of the CODEC is programmed to the
> >> appropriate value, both AACIBITCLK and AACISDATAIN are brought to, and
> >> held at 0.", refer to this register IMHO.
> >
> > But the above says "the power down control and status register (0x26) of
> > the CODEC". So this refers to the AC97 registers rather than the AACI
> > registers. Your patch reads from the AACI registers. The AC97 registers
> > I think are access with aaci_ac97_(read|write) functions.
> >
> 
> I think its snd_ac97_read().

Which calls aaci_ac97_read().

> But they internally again use readl/writel. Won't these cause
> alignment issues again?

The AC97 registers are read by writing the register number (0x26 in this
case) to AACI_SL1TX (32-bit register and correctly aligned) and reading
the result from AACI_SLFR. There is no readl/writel to something with
offset 0x26.

-- 
Catalin