On Thu, Jul 13, 2023 at 07:55:31AM +0200, Takashi Iwai wrote:
On Wed, 12 Jul 2023 16:57:49 +0200,
Oswald Buddenhagen wrote:
The mixer, PCM prepare, MIDI, synth driver, and procfs callbacks are all
always invoked with IRQs enabled, so there is no point in saving the
state.
snd_emu1010_load_firmware_entry() is called from emu1010_firmware_work()
and snd_emu10k1_emu1010_init(); the latter from snd_emu10k1_create() and
snd_emu10k1_resume(), all of which have IRQs enabled.
The voice and memory functions are called from mixed contexts, so they
keep the state saving.
The low-level functions all keep the state saving, because it's not
feasible to keep track of what is called where.
Wouldn't it make more sense if you replace it with a mutex?
It'll become more obvious that it's only for non-IRQ context, too.
huh?
at least some of the ~six different locks touched by this patch
absolutely _are_ used in irq context. this patch is concerned only about
the specific call sites, where we know that local irqs are enabled, so
we can unconditionally re-enable them rather than restoring the old
state (the latter being a much more expensive operation). the code
already contains precedents for this, and the complementary optimization
of not disabling/restoring irqs where we know that they are already
disabled.
the reg_lock would be convertible to a mixer_mutex in most mixer
callbacks, but that is an orthogonal question, which is raised in the
next commit.
regards
