Re: [PATCH v5 01/10] hw/arm/ast27x0: Start SSP in powered-off state to match hardware behavior

On 7/8/26 11:20, Jamin Lin wrote:
> In the previous design, both the PSP and SSP were started together during
> SoC initialization. However, on real hardware, the SSP begins in a powered-off
> state. The typical boot sequence involves the PSP powering up first, loading
> the SSP firmware binary into shared memory via DRAM remap, and then releasing
> the SSP reset and enabling it through SCU control registers.
> 
> To more accurately model this behavior in QEMU, this commit sets the
> "start-powered-off" property for the SSP's ARMv7M core. This change ensures
> the SSP remains off until explicitly enabled via the SCU, simulating the
> real-world flow where the PSP controls SSP boot through SCU interaction.
> 
> Signed-off-by: Jamin Lin <[email protected]>
> ---
>   hw/arm/aspeed_ast27x0-ssp.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/hw/arm/aspeed_ast27x0-ssp.c b/hw/arm/aspeed_ast27x0-ssp.c
> index e03653086c..9c984d23cd 100644
> --- a/hw/arm/aspeed_ast27x0-ssp.c
> +++ b/hw/arm/aspeed_ast27x0-ssp.c
> @@ -192,6 +192,13 @@ static void aspeed_soc_ast27x0ssp_realize(DeviceState *dev_soc, Error **errp)
>       qdev_connect_clock_in(armv7m, "cpuclk", s->sysclk);
>       object_property_set_link(OBJECT(&a->armv7m), "memory",
>                                OBJECT(s->memory), &error_abort);
> +    /*
> +     * The SSP starts in a powered-down state and can be powered up
> +     * by setting the SSP Control Register through the SCU
> +     * (System Control Unit)
> +     */
> +    object_property_set_bool(OBJECT(&a->armv7m), "start-powered-off", true,
> +                             &error_abort);
>       sysbus_realize(SYS_BUS_DEVICE(&a->armv7m), &error_abort);
>   
>       /* SDRAM */

Reviewed-by: Cédric Le Goater <[email protected]>

Thanks,

C.