[PATCH] mach-snapdragon: do carveouts for qcs404 only

[Sumit Garg]

Hi Sam,

On Wed, 8 May 2024 at 00:11, Sam Day <me at samcday.com> wrote:
>
> The newly introduced carve_out_reserved_memory causes issues when
> U-Boot is chained from the lk2nd bootloader. lk2nd provides a
> simple-framebuffer device and marks the framebuffer region as no-map in
> the supplied /reserved-memory. Consequently, the simple_video driver
> triggers a page fault when it tries to write to this region.

How does the corresponding Linux kernel driver handle this? Is the
framebuffer region required to be mapped as normal memory or device
type or something else? Similarly would normal memory type work for
all other reserved memory regions marked as no-map?

-Sumit

>
> As per Caleb's advice, this simple patch only does the carveouts for the
> qcs404 SoC for which it was originally designed. The intent is to do the
> carveouts for more Qualcomm SoCs in future.
>
> ---
> I'm not sure if it's feasible to get this in for the 2024.07 release,
> but it'd be great if we could - it's the only thing that breaks U-Boot
> master on msm8916 devices that chain from lk2nd.
>
> Signed-off-by: Sam Day <me at samcday.com>
> ---
>  arch/arm/mach-snapdragon/board.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c
> index 3d5994c878..b439a19ec7 100644
> --- a/arch/arm/mach-snapdragon/board.c
> +++ b/arch/arm/mach-snapdragon/board.c
> @@ -467,10 +467,12 @@ void enable_caches(void)
>         gd->arch.tlb_addr = tlb_addr;
>         gd->arch.tlb_size = tlb_size;
>
> -       carveout_start = get_timer(0);
> -       /* Takes ~20-50ms on SDM845 */
> -       carve_out_reserved_memory();
> -       debug("carveout time: %lums\n", get_timer(carveout_start));
> -
> +       /* We do the carveouts only for QCS404, for now. */
> +       if (fdt_node_check_compatible(gd->fdt_blob, 0, "qcom,qcs404") == 0) {
> +               carveout_start = get_timer(0);
> +               /* Takes ~20-50ms on SDM845 */
> +               carve_out_reserved_memory();
> +               debug("carveout time: %lums\n", get_timer(carveout_start));
> +       }
>         dcache_enable();
>  }
>
> ---
> base-commit: 1c40dda60f5f7e83a6d6f541cf5a57eb7e8ec43c
> change-id: 20240507-qcs404-carveout-only-7a15bbf3fd89
>
> Best regards,
> --
> Sam Day <me at samcday.com>
>
>