[PATCH] firmware: scmi: Drop mmu_set_region_dcache_behaviour() misuse

[Patrice CHOTARD]

On 10/25/25 23:35, Marek Vasut wrote:
> MMU region cache behavior configuration for SCMI/SMT mailboxes is
> platform specific. Even on ARM systems, the mailbox memory may not
> even be located in any cacheable MMU region and may instead reside
> in some SRAM. Remove this non-generic cache behavior configuration
> code from generic code path.
> 
> It is unlikely that any platform is affected by this change if it
> did configure its MMU regions correctly on start up. Platforms
> which might be affected are i.MX94/95 and STM32MP.
> 
> Fixes: 240720e9052f ("firmware: scmi: mailbox/smt agent device")
> Fixes: 2a3f161c8b16 ("scmi: correctly configure MMU for SCMI buffer")
> Fixes: b2ae10970d40 ("firmware: scmi: use PAGE_SIZE alignment for ARM64")
> Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
> ---
> Cc: Alice Guo <alice.guo at nxp.com>
> Cc: Etienne Carriere <etienne.carriere at linaro.org>
> Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
> Cc: Peng Fan <peng.fan at nxp.com>
> Cc: Tom Rini <trini at konsulko.com>
> Cc: Vinh Nguyen <vinh.nguyen.xz at renesas.com>
> Cc: Viorel Suman <viorel.suman at nxp.com>
> Cc: Ye Li <ye.li at nxp.com>
> Cc: u-boot at lists.denx.de
> ---
>  drivers/firmware/scmi/smt.c | 14 --------------
>  1 file changed, 14 deletions(-)
> 
> diff --git a/drivers/firmware/scmi/smt.c b/drivers/firmware/scmi/smt.c
> index 237871559f0..cd1c0801f72 100644
> --- a/drivers/firmware/scmi/smt.c
> +++ b/drivers/firmware/scmi/smt.c
> @@ -61,20 +61,6 @@ int scmi_dt_get_smt_buffer(struct udevice *dev, struct scmi_smt *smt)
>  	if (device_is_compatible(dev, "arm,scmi") && ofnode_has_property(dev_ofnode(dev), "mboxes"))
>  		scmi_smt_enable_intr(smt, true);
>  
> -#ifdef CONFIG_ARM
> -	if (dcache_status()) {
> -		u32 align_size;
> -
> -		if (IS_ENABLED(CONFIG_ARM64))
> -			align_size = PAGE_SIZE;
> -		else
> -			align_size = MMU_SECTION_SIZE;
> -
> -		mmu_set_region_dcache_behaviour(ALIGN_DOWN((uintptr_t)smt->buf, align_size),
> -						ALIGN(smt->size, align_size), DCACHE_OFF);
> -	}
> -#endif
> -
>  	return 0;
>  }
>  

Hi Marek

Tested-by: Patrice Chotard <patrice.chotard at foss.st.com>

Tested on stm32mp257f-ev1 board.

Thanks
Patrice