Re: CMA allocation fails with default 128M on X1E80100 (Lenovo 21N1CT01WW) for ath12k

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 3/2/26 12:19 PM, Konrad Dybcio wrote:
> On 2/28/26 10:29 AM, René Mérou wrote:
>> Hi,
>> I'm experiencing CMA allocation failures with the ath12k WiFi driver on my new Lenovo 21N1CT01WW (Snapdragon X1E80100).
>>
>> Error in dmesg
>>   cma: __cma_alloc: reserved: alloc failed, req-size: 257 pages, ret: -16
>>   cma: => 1042 free of 32768 total pages
>>
>> System details
>>     Kernel: 6.17.0-8-qcom-x1e (Ubuntu)
>>     Default CMA size: 128M (set by the distribution for this hardware)
>>     WiFi chip: ath12k_pci (Qualcomm WCN685x)
>>
>> What I found
>>     With the default 128M CMA, the allocation of 257 pages (~1MB) fails
>>     After increasing CMA to 256M (by adding cma=256M to the kernel command line), the error disappears and WiFi works correctly
>>
>> My questions
>>     Is 128M expected to be sufficient for ath12k on this platform?
>>     Could the driver be optimized to need less contiguous memory?
>>     Should the default CMA size be increased to 256M for X1E80100 devices?
> 
> The default value in the arm64 defconfig is CONFIG_CMA_SIZE_MBYTES=32,
> although most laptop DTs individually add a 128M zone under /reserved-memory
> 
> We should probably enlarge this value in either of those places, although I
> don't know whether changing the defconfig is going to be welcomed..

+CC FYI

Konrad