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DateSat, 28 May 2011 16:21:39 +0200
FromTakashi Iwai <>
SubjectRe: i8253 locking and PC speaker on non-{mips,x86}
At Sat, 28 May 2011 12:21:20 +0100,
Ralf Baechle wrote:
>
> No longer terribly relevant these days but ...
>
> drivers/input/misc/pcspkr.c:
>
> #if defined(CONFIG_MIPS) || defined(CONFIG_X86)
> /* Use the global PIT lock ! */
> #include <asm/i8253.h>
> #else
> #include <asm/8253pit.h>
> static DEFINE_RAW_SPINLOCK(i8253_lock);
> #endif
>
> sound/drivers/pcsp/pcsp.h:
>
> #if defined(CONFIG_MIPS) || defined(CONFIG_X86)
> /* Use the global PIT lock ! */
> #include <asm/i8253.h>
> #else
> #include <asm/8253pit.h>
> static DEFINE_RAW_SPINLOCK(i8253_lock);
>
> $ git grep -F pcsp.h sound/drivers/pcsp
> sound/drivers/pcsp/pcsp.c:#include "pcsp.h"
> sound/drivers/pcsp/pcsp_input.c:#include "pcsp.h"
> sound/drivers/pcsp/pcsp_lib.c:#include "pcsp.h"
> sound/drivers/pcsp/pcsp_mixer.c:#include "pcsp.h"
> $ git grep -w i8253_lock sound/drivers/pcsp/
> sound/drivers/pcsp/pcsp.h:static DEFINE_RAW_SPINLOCK(i8253_lock);
> sound/drivers/pcsp/pcsp_input.c: raw_spin_lock_irqsave(&i8253_lock, flags
> sound/drivers/pcsp/pcsp_input.c: raw_spin_unlock_irqrestore(&i8253_lock,
> sound/drivers/pcsp/pcsp_lib.c: raw_spin_lock_irqsave(&i8253_lock, flags
> sound/drivers/pcsp/pcsp_lib.c: raw_spin_unlock_irqrestore(&i8253_lock,
> sound/drivers/pcsp/pcsp_lib.c: raw_spin_lock(&i8253_lock);
> sound/drivers/pcsp/pcsp_lib.c: raw_spin_unlock(&i8253_lock);
> sound/drivers/pcsp/pcsp_lib.c: raw_spin_lock(&i8253_lock);
> sound/drivers/pcsp/pcsp_lib.c: raw_spin_unlock(&i8253_lock);
>
> Locks are great, everybody should have their own lock!

Yeah, if they were actually built. But snd-pcsp driver is built only
for x86:

config SND_PCSP
tristate "PC-Speaker support (READ HELP!)"
depends on PCSPKR_PLATFORM && X86 && HIGH_RES_TIMERS
depends on INPUT
depends on EXPERIMENTAL

So, the current code in sound/drivers/pcsp/pcsp.h is harmless, but
just confusing because of copy-and-paste from
drivers/input/misc/pcspkr.c.
The part for non-x86 should be removed or commented better.


thanks,

Takashi


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