Re: [PATCH v5 4/5] Input: cs40l50 - Add support for the CS40L50 haptic driver

[James Ogletree]

Hi Dmitry,

> On Jan 12, 2024, at 9:41 AM, James Ogletree <James.Ogletree@xxxxxxxxxx> wrote:
> 
>> On Jan 11, 2024, at 1:28 AM, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
>> 
>> On Wed, Jan 10, 2024 at 02:36:55PM +0000, James Ogletree wrote:
>>> 
>>>> On Jan 9, 2024, at 4:31 PM, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
>>>> 
>>>> On Tue, Jan 09, 2024 at 10:03:02PM +0000, James Ogletree wrote:
>>>>> 
>>>>> 
>>>>>> On Jan 6, 2024, at 7:58 PM, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
>>>>>> 
>>>>>> On Thu, Jan 04, 2024 at 10:36:37PM +0000, James Ogletree wrote:
>>>>>>> + } else {
>>>>>>> + queue_work(info->vibe_wq, &info->vibe_stop_work);
>>>>>> 
>>>>>> Which effect are you stopping? All of them? You need to stop a
>>>>>> particular one.
>>>>> 
>>>>> Our implementation of “stop” stops all effects in flight which is intended.
>>>>> That is probably unusual so I will add a comment here in the next
>>>>> version.
>>>> 
>>>> Again, please implement the driver properly, not define your own
>>>> carveouts for the expected behavior.
>>> 
>>> Ack, and a clarification question: the device is not actually able to
>>> play multiple effects at once. In that case, does stopping a specific
>>> effect entail just cancelling an effect in the queue?
>> 
>> In this case I believe the device should declare maximum number of
>> effects as 1. Userspace is supposed to determine maximum number of
>> simultaneously playable effects by issuing EVIOCGEFFECTS ioctl on the
>> corresponding event device.
> 
> Is it possible to specify the device’s maximum simultaneous effects
> without also restricting the number of effects the user can upload? It
> looks like both are tied to ff->max_effects.
> 
> Best,
> James
> 

Is there an opportunity here for a subsystem change to disassociate max
upload-able effects and max simultaneously playable effects, or if not what
do you advise in the case of a device in which the two differ? Or is this
a misuse of the subsystem in some way?

Best,
James