Hi Ping,
[...]
>> @@ -51,7 +52,9 @@ static DEFINE_MUTEX(evdev_table_mutex);
>>
>> static int evdev_compute_buffer_size(struct input_dev *dev)
>> {
>> - return EVDEV_MIN_BUFFER_SIZE;
>> + int nev = dev->hint_events_per_packet * EVDEV_BUF_PACKETS;
>> + nev = max(nev, EVDEV_MIN_BUFFER_SIZE);
>> + return roundup_pow_of_two(nev);
>
> I think we have a backward compatibility issue here. This routine will
> return 7 when nev falls to the default value
> (EVDEV_MIN_BUFFER_SIZE/64). This could happen to those drivers that
> don't report MT events or forget/don't feel the need to set
> hint_events_per_packet since the old BUFFER_SIZE worked perfectly for
> them. We need to keep the return value for those drivers as 64 so we
> could allocate the same space as it was in [PATCH 1/5].
Are you perhaps confusing EVDEV_BUF_PACKETS and EVDEV_MIN_BUFFER_SIZE? The last
line ensures that the value returned is a power of two (hence not 7). The
second-to-last line ensures the value is at least equal to 64 (hence not 7). The
default hint value for a driver that does not do anything is zero, which leads
to a return value of 64, just as it is today.
Thanks,
Henrik
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