Subject: Re: TC bba audio problem on DEC3000/300
To: Jason R Thorpe <thorpej@zembu.com>
From: Gregory McGarry <g.mcgarry@ieee.org>
List: port-alpha
Date: 07/14/2000 07:38:07
Jason R Thorpe wrote:
> > Is anyone working to update tc_bus_mem.c to fix this?
> > Anyway, bba configuration in TCWSCONS should be disabled for now...
>
> Actually, this is a bug in the `bba' driver.
>
> Alpha and DECstation are little-endian, and the bytes happen to be
> padded out. So, do 4-byte access with the byte you want in the least
> significant 8-bits of the 4-byte longword.
>
> The following patch should make it go:
[cut]
I tested your patch on pmax and there are no problems.
> Anyway, I also noticed that there's a TIMETOWASTE constant in there
> which looks like it was intended to implement a recovery delay. It
> doesn't work -- the compiler optimizes the loop right out. If the
> delay is really needed (which I would guess it is not, since it's
> not actually there right now), it should be done with delay().
With the internal toolchain, the loop is not 'optimised out' on the
mips. Nevertheless, I removed the spin-loop and a quick evaluation
indicates the driver continues to operate correctly on pmax.
-- Gregory McGarry <g.mcgarry@ieee.org>