* Ohad Ben-Cohen o...@wizery.com [101018 00:41]:
From: Simon Que s...@ti.com
Add driver for OMAP's Hardware Spinlock module.
The OMAP Hardware Spinlock module, initially introduced in OMAP4,
provides hardware assistance for synchronization between the
multiple processors in the device
On Thursday 21 October 2010, Ohad Ben-Cohen wrote:
This sounds like adding a set of API that resembles spin_{unlock,lock}_irq.
My gut feeling here is that while this may be useful and simple at
certain places, it is somewhat error prone; a driver which would
erroneously use this at the wrong
On Thu, Oct 21, 2010 at 11:04 AM, Arnd Bergmann a...@arndb.de wrote:
On Thursday 21 October 2010, Ohad Ben-Cohen wrote:
This sounds like adding a set of API that resembles spin_{unlock,lock}_irq.
My gut feeling here is that while this may be useful and simple at
certain places, it is somewhat
On Thursday 21 October 2010, Ohad Ben-Cohen wrote:
The change is also pretty trivial:
* move the internal locking implementation to raw_ methods
* the raw_ methods would save the current interrupt state only if
given a placeholder
* wrap those raw_ methods with the desired API (but only
On Tue, Oct 19, 2010 at 7:16 PM, Kevin Hilman
khil...@deeprootsystems.com wrote:
Ohad Ben-Cohen o...@wizery.com writes:
From: Simon Que s...@ti.com
Add driver for OMAP's Hardware Spinlock module.
The OMAP Hardware Spinlock module, initially introduced in OMAP4,
provides hardware assistance
Ohad Ben-Cohen o...@wizery.com writes:
On Tue, Oct 19, 2010 at 7:16 PM, Kevin Hilman
khil...@deeprootsystems.com wrote:
Ohad Ben-Cohen o...@wizery.com writes:
From: Simon Que s...@ti.com
Add driver for OMAP's Hardware Spinlock module.
The OMAP Hardware Spinlock module, initially
On Tue, Oct 19, 2010 at 11:08 PM, Arnd Bergmann a...@arndb.de wrote:
Right. There are two more things to consider though:
If you know that interrupts are disabled, you may still want to avoid
having to save the interrupt flag to the stack, to save some cycles
saving and restoring it. I don't
On Mon, Oct 18, 2010 at 09:44:33AM +0200, Ohad Ben-Cohen wrote:
+#else /* !CONFIG_OMAP_HWSPINLOCK */
+
+static inline struct omap_hwspinlock *omap_hwspinlock_request(void)
+{
+ return ERR_PTR(-ENOSYS);
+}
One note, do you really want to fail if this option isn't built into the
kernel,
Ohad Ben-Cohen o...@wizery.com writes:
From: Simon Que s...@ti.com
Add driver for OMAP's Hardware Spinlock module.
The OMAP Hardware Spinlock module, initially introduced in OMAP4,
provides hardware assistance for synchronization between the
multiple processors in the device (Cortex-A9,
On Mon, Oct 18, 2010 at 1:44 AM, Ohad Ben-Cohen o...@wizery.com wrote:
From: Simon Que s...@ti.com
Add driver for OMAP's Hardware Spinlock module.
The OMAP Hardware Spinlock module, initially introduced in OMAP4,
provides hardware assistance for synchronization between the
multiple
Ohad Ben-Cohen o...@wizery.com writes:
From: Simon Que s...@ti.com
Add driver for OMAP's Hardware Spinlock module.
The OMAP Hardware Spinlock module, initially introduced in OMAP4,
provides hardware assistance for synchronization between the
multiple processors in the device (Cortex-A9,
On Monday 18 October 2010 09:44:33 Ohad Ben-Cohen wrote:
+ int omap_hwspin_lock(struct omap_hwspinlock *hwlock, unsigned long *flags);
...
+ The flags parameter is a pointer to where the interrupts state of the
+ caller will be saved at.
This seems to encourage sloppy coding: The
On Tue, Oct 19, 2010 at 5:46 PM, Greg KH g...@kroah.com wrote:
On Mon, Oct 18, 2010 at 09:44:33AM +0200, Ohad Ben-Cohen wrote:
+#else /* !CONFIG_OMAP_HWSPINLOCK */
+
+static inline struct omap_hwspinlock *omap_hwspinlock_request(void)
+{
+ return ERR_PTR(-ENOSYS);
+}
One note, do you
On Tue, Oct 19, 2010 at 6:58 PM, Kevin Hilman
khil...@deeprootsystems.com wrote:
+ * This spin_trylock_irqsave serves two purposes:
+
+ * 1. Disable local interrupts and preemption, in order to
+ * minimize the period of time in which the hwspinlock
+ * is taken (so
On Tue, Oct 19, 2010 at 7:01 PM, Grant Likely grant.lik...@secretlab.ca wrote:
+ struct omap_hwspinlock *omap_hwspinlock_request(void);
...
ERR_PTR() is only appropriate when the caller actually cares about the
failure code and has different behaviour depending on the result.
Agree; the
On Tue, Oct 19, 2010 at 7:21 PM, Arnd Bergmann a...@arndb.de wrote:
On Monday 18 October 2010 09:44:33 Ohad Ben-Cohen wrote:
+ int omap_hwspin_lock(struct omap_hwspinlock *hwlock, unsigned long
*flags);
...
+ The flags parameter is a pointer to where the interrupts state of the
+
On Tuesday 19 October 2010 22:43:34 Ohad Ben-Cohen wrote:
Disabling irqs might be a concern as a source of RT latency. It
might be better to make the caller responsible for managing local spin
locks and irq disable/enable.
This a coming from an hardware requirement, rather than a choice
On Tuesday 19 October 2010 22:51:22 Ohad Ben-Cohen wrote:
, which is generally discouraged
in all places where you know if you need to disable interrupts or not.
IMHO the default should be a version that only allows locks that don't get
taken at IRQ time and consequently don't require
On Tue, Oct 19, 2010 at 10:58 PM, Arnd Bergmann a...@arndb.de wrote:
If a hwspinlock is taken over a long period of time, its other user
(with which we try to achieve synchronization) might be polling the
OMAP interconnect for too long (trying to take the hwspinlock) and
thus preventing it to
From: Simon Que s...@ti.com
Add driver for OMAP's Hardware Spinlock module.
The OMAP Hardware Spinlock module, initially introduced in OMAP4,
provides hardware assistance for synchronization between the
multiple processors in the device (Cortex-A9, Cortex-M3 and
C64x+ DSP).
Signed-off-by: Simon
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