[PATCH v3 06/22] arm: mach-k3: common: Add lpm_resume_from_ddr

[Akashdeep Kaur]

Hi Markus,

On 23/06/25 17:38, Markus Schneider-Pargmann wrote:
> This is a common function that helps to resume from DDR. There are two
> pointers which are fetched from DDR to resume, the TIFS context pointer
> which points to the context in DDR. There is another pointer to the DM
> loadaddr to jump back into DM.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp at baylibre.com>
> ---
>   arch/arm/mach-k3/common.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>   arch/arm/mach-k3/common.h |  1 +
>   2 files changed, 46 insertions(+)
> 
> diff --git a/arch/arm/mach-k3/common.c b/arch/arm/mach-k3/common.c
> index 7c3f42e35b0f3a5aa7ed0bf01a1479b29d947540..1ef560e2fb936c4245323bbebc5af3ec277b8792 100644
> --- a/arch/arm/mach-k3/common.c
> +++ b/arch/arm/mach-k3/common.c

> +struct lpm_meta_data {
> +	u64 dm_jump_address;
> +	u64 tifs_context_save_address;
> +	u64 reserved[30];
> +} __packed__;
> +
> +void __noreturn lpm_resume_from_ddr(u64 meta_data_addr)
> +{
> +	struct lpm_meta_data *lpm_data = (struct lpm_meta_data *)meta_data_addr;
> +	typedef void __noreturn (*image_entry_noargs_t)(void);
> +	image_entry_noargs_t image_entry;
> +	int ret;
> +
> +	ret = lpm_restore_context(lpm_data->tifs_context_save_address);
> +	if (ret)
> +		panic("Failed to restore context from 0x%p\n",
> +		      (void *)lpm_data->tifs_context_save_address);

The above code is reading the value of 
lpm_data->tifs_context_save_address two times from DDR memory,
1. While requesting TIFS to restore the context
2. When printing the address sent to TIFS to restore the context in case 
of failure

It is better to read the address once from DDR memory and store in local 
variable as we need to print the exact address that was sent to TIFS for 
restoring context. (In case the DDR memory is instable, this read can 
have different values and can be misleading)

> +
> +	image_entry = (image_entry_noargs_t)(u64 *)lpm_data->dm_jump_address;
> +	printf("Resuming from DDR, jumping to stored DM loadaddr 0x%p, TIFS context restored from 0x%p\n",
> +	       image_entry, (void *)lpm_data->tifs_context_save_address);
> +
> +	image_entry();
> +}
> +#else
> +

Regards,
Akashdeep Kaur