[Sound-open-firmware] Commit c80270e7e49 (" ipc: structures should all be aligned on 4 bytes") causes issues on i.MX8

[Girdwood, Liam R]

Hi Daniel,

On Tue, 2021-05-11 at 15:02 +0000, Daniel Baluta wrote:
> Hi Liam,
> 
> I noticed this SOF commit: 
> 
> commit c80270e7e49d26a34fe284d1868e7d9cb80104f1Author: Liam Girdwood
> <liam.r.girdwood at linux.intel.com>
> Date:   Sat Apr 3 21:22:21 2021 +0100
> 
>     ipc: structures should all be aligned on 4 bytes
>     
>     Give the compiler a chance to further optimise IPC data access
> since it's
>     all on a 4 byte alignment.
>     
>     Signed-off-by: Liam Girdwood <liam.r.girdwood at linux.intel.com>
> 
> 
> It looks like it triggers some issues on i.MX8. 
> 
> Is there any equivalent for Linux kernel? Some structures are shared
> with the kernel
> and on arm64 it assumes default alignment as 8 hence I get a mismatch
> at least when
> printing DAI / Host position
> 
> 
> +       dev_info(sdev->dev, "posn : host 0x%llx dai 0x%llx wall
> 0x%llx no_per %d\n",
> +                posn.host_posn, posn.dai_posn, posn.wallclock,
> stream->substream->runtime->no_period_wakeup);
> 

It looks like the uint64_t on the sof_ipc_stream_position are not
aligned on 8 bytes (with the packing, there are 7 * uint32_t before
them) and the ARM compiler is expecting a 8 byte alingment for uint64 ?

I'm not sure why this is showing up now as the "packed" attribute would
force the uint64_t to be aligned on 4 bytes instead of 8 here.

Btw, have you tried setting aligned(8) here ? or tried removing the
aligned(4) for stream_posn ?

Liam

> thanks,
> Daniel.
> 

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