Re: [PATCH] wifi: ath11k: fix qmi memory allocation logic for CALDB region

[Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>]

On 12/6/2025 11:28 PM, Alexandru Gagniuc wrote:
> Memory region assignment in ath11k_qmi_assign_target_mem_chunk()
> assumes that:
>    1. firmware will make a HOST_DDR_REGION_TYPE request, and
>    2. this request is processed before CALDB_MEM_REGION_TYPE
> 
> In this case CALDB_MEM_REGION_TYPE, can safely be assigned immediately
> after the host region.
> 
> However, if the HOST_DDR_REGION_TYPE request is not made, or the

AFAICT, this is highly unlikely as HOST_DDR_REGION_TYPE will always be before
CALDB_MEM_REGION_TYPE.

> reserved-memory node is not present, then res.start and res.end are 0,
> and host_ddr_sz remains uninitialized. The physical address should
> fall back to ATH11K_QMI_CALDB_ADDRESS. That doesn't happen:
> 
> resource_size(&res) returns 1 for an empty resource, and thus the if
> clause never takes the fallback path. ab->qmi.target_mem[idx].paddr
> is assigned the uninitialized value of host_ddr_sz + 0 (res.start).
> 
> Use "if (res.end > res.start)" for the predicate, which correctly
> falls back to ATH11K_QMI_CALDB_ADDRESS.
> 
> Fixes: 900730dc4705 ("wifi: ath: Use of_reserved_mem_region_to_resource() for "memory-region"")
> 
> Cc: stable@vger.kernel.org # v6.18
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> ---
>   drivers/net/wireless/ath/ath11k/qmi.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath11k/qmi.c b/drivers/net/wireless/ath/ath11k/qmi.c
> index aea56c38bf8f3..6cc26d1c1e2a4 100644
> --- a/drivers/net/wireless/ath/ath11k/qmi.c
> +++ b/drivers/net/wireless/ath/ath11k/qmi.c
> @@ -2054,7 +2054,7 @@ static int ath11k_qmi_assign_target_mem_chunk(struct ath11k_base *ab)
>   				return ret;
>   			}
>   
> -			if (res.end - res.start + 1 < ab->qmi.target_mem[i].size) {
> +			if (resource_size(&res) < ab->qmi.target_mem[i].size) {
>   				ath11k_dbg(ab, ATH11K_DBG_QMI,
>   					   "fail to assign memory of sz\n");
>   				return -EINVAL;
> @@ -2086,7 +2086,7 @@ static int ath11k_qmi_assign_target_mem_chunk(struct ath11k_base *ab)
>   			}
>   
>   			if (ath11k_core_coldboot_cal_support(ab)) {
> -				if (resource_size(&res)) {
> +				if (res.end > res.start) {
>   					ab->qmi.target_mem[idx].paddr =
>   							res.start + host_ddr_sz;
>   					ab->qmi.target_mem[idx].iaddr =

The rest looks good.

Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>