Re: [PATCH] crypto: qce - Remove driver

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

On 7/29/26 4:55 PM, Eric Biggers wrote:
> On Wed, Jul 29, 2026 at 10:02:27AM +0200, Konrad Dybcio wrote:
>> On 7/28/26 5:22 PM, Eric Biggers wrote:
>>> On Fri, Jul 24, 2026 at 08:51:44AM -0700, Eric Biggers wrote:
>>>> It is consuming a lot of the community's time to help maintain,
>>>> including dealing with LLM-found bugs, with no clear benefit to anyone.
>>>> Even considering *just today* we can see someone sent a bug fix:
>>>> https://lore.kernel.org/linux-crypto/20260724081537.191992-2-thorsten.blum@linux.dev/
>>>
>>> Another example:
>>> https://lore.kernel.org/linux-crypto/d5de5a55-eb35-4ad5-8d53-12e188e156cb@oss.qualcomm.com/
>>>
>>>> It definitely *was* causing problems before it was disabled via the
>>>> crypto priority system (which made it unused in the kernel) and dropped
>>>> it from AF_ALG (which removed most of the unprivileged attack surface).
>>>> When anyone accidentally used it, it caused at least a huge performance
>>>> problem, and sometimes other problems too like filesystem hangs.  It was
>>>> an issue for years.
>>>
>>> This actually seems to have been an overly-optimistic characterization!
>>> As per
>>> https://lore.kernel.org/linux-crypto/d5de5a55-eb35-4ad5-8d53-12e188e156cb@oss.qualcomm.com/
>>> this driver drains the battery on every system with the module loaded,
>>> even when no crypto requests are actually sent to it.
>>
>> Unfortunately removing it drains way more battery, because the buses
>> never hit sync_state and are kept at their maximum frequencies:
>>
>> [   18.021823] qnoc-glymur interconnect-1: sync_state() pending due to 1dfa000.crypto
>> [   18.029605] qnoc-glymur 16e0000.interconnect: sync_state() pending due to 1dfa000.crypto
>>
>> (it transiently also pins DRAM and friends to max-freq which absolutely
>> kills battery life)
> 
> Isn't that easily fixable by marking the node as "disabled" in the
> device tree, or even just deleting it entirely?

Avoided? Yes. Fixed? No. The DT is valid but Linux can't deal with it
[since the driver is gone]

Konrad