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SubjectRe: [RFC/PATCH 3/3] mfd: twl4030-irq: implement bus_*lock
Hi,

On Wed, Dec 29, 2010 at 02:38:28AM +0200, Felipe Balbi wrote:
>On Tue, 2010-12-28 at 23:58 +0000, Mark Brown wrote:
>> On Tue, Dec 28, 2010 at 07:14:19PM +0200, Felipe Balbi wrote:
>>
>> > +static void twl4030_sih_bus_sync_unlock(unsigned int irq)
>> > +{
>> > + struct sih_agent *agent = get_irq_chip_data(irq);
>> > +
>> > + mutex_unlock(&agent->irq_lock);
>> > +}
>>
>> I suspect you need to do some sort of sync with the hardware here - the
>> _sync bit of the name comes from the fact that the mask and unmask stuff
>> is still called with IRQs disabled and so can't touch and I2C chip, this
>> is called after reenabling them give a chance for the updates done to
>> be reflected in the hardware. The implementation everyone else has done
>> is to update a register cache in the other functions then write that
>> out here before dropping the mutex.
>
>now that I look at some gpio chips I see what you're saying, will update
>that tomorrow. Thanks

I believe you meant something like below, I'll get back to this in a
little while. Have lots to test:

From f15801a5d57041b7669222bdb7cccf8b592c2f63 Mon Sep 17 00:00:00 2001
From: Felipe Balbi <balbi@ti.com>
Date: Tue, 28 Dec 2010 19:07:33 +0200
Subject: [PATCH 1/2] mfd: twl4030-irq: implement bus_*lock
Organization: Texas Instruments\n

drop all the locking around mask/unmask and
implement bus_lock and bus_sync_unlock methods.

Signed-off-by: Felipe Balbi <balbi@ti.com>
---
drivers/mfd/twl4030-irq.c | 101 ++++++++++++++++++++++-----------------------
1 files changed, 50 insertions(+), 51 deletions(-)
diff --git a/drivers/mfd/twl4030-irq.c b/drivers/mfd/twl4030-irq.c
index 298956d..84f6066 100644
--- a/drivers/mfd/twl4030-irq.c
+++ b/drivers/mfd/twl4030-irq.c
@@ -440,6 +440,7 @@ struct sih_agent {
const struct sih *sih;

u32 imr;
+ bool imr_change_pending;
u32 edge_change;

struct mutex irq_lock;
@@ -450,64 +451,23 @@ struct sih_agent {
static void twl4030_sih_mask(unsigned irq)
{
struct sih_agent *agent = get_irq_chip_data(irq);
- const struct sih *sih = agent->sih;
-
- union {
- u8 bytes[4];
- u32 word;
- } imr;
-
- int status;

agent->imr |= BIT(irq - agent->irq_base);
-
- mutex_lock(&agent->irq_lock);
-
- /* byte[0] gets overwritten as we write ... */
- imr.word = cpu_to_le32(agent->imr << 8);
-
- /* write the whole mask ... simpler than subsetting it */
- status = twl_i2c_write(sih->module, imr.bytes,
- sih->mask[irq_line].imr_offset, sih->bytes_ixr);
- if (status)
- pr_err("twl4030: %s, %s --> %d\n", __func__,
- "write", status);
- mutex_unlock(&agent->irq_lock);
+ agent->imr_change_pending = true;
}

static void twl4030_sih_unmask(unsigned irq)
{
struct sih_agent *agent = get_irq_chip_data(irq);
- const struct sih *sih = agent->sih;

- union {
- u8 bytes[4];
- u32 word;
- } imr;
-
- int status;
-
- mutex_lock(&agent->irq_lock);
agent->imr &= ~BIT(irq - agent->irq_base);
-
- /* byte[0] gets overwritten as we write ... */
- imr.word = cpu_to_le32(agent->imr << 8);
-
- /* write the whole mask ... simpler than subsetting it */
- status = twl_i2c_write(sih->module, imr.bytes,
- sih->mask[irq_line].imr_offset, sih->bytes_ixr);
- if (status)
- pr_err("twl4030: %s, %s --> %d\n", __func__,
- "write", status);
- mutex_unlock(&agent->irq_lock);
+ agent->imr_change_pending = true;
}

static int twl4030_sih_set_type(unsigned irq, unsigned trigger)
{
struct sih_agent *agent = get_irq_chip_data(irq);
- const struct sih *sih = agent->sih;
struct irq_desc *desc = irq_to_desc(irq);
- int status = 0;

if (!desc) {
pr_err("twl4030: Invalid IRQ: %d\n", irq);
@@ -517,17 +477,57 @@ static int twl4030_sih_set_type(unsigned irq, unsigned trigger)
if (trigger & ~(IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
return -EINVAL;

- mutex_lock(&agent->irq_lock);
if ((desc->status & IRQ_TYPE_SENSE_MASK) != trigger) {
- u8 bytes[6];
- u32 edge_change;
+ agent->edge_change |= BIT(irq - agent->irq_base);

desc->status &= ~IRQ_TYPE_SENSE_MASK;
desc->status |= trigger;
- agent->edge_change |= BIT(irq - agent->irq_base);
+ }
+
+ return 0;
+}
+
+static void twl4030_sih_bus_lock(unsigned int irq)
+{
+ struct sih_agent *agent = get_irq_chip_data(irq);
+
+ mutex_lock(&agent->irq_lock);
+}
+
+static void twl4030_sih_bus_sync_unlock(unsigned int irq)
+{
+ struct sih_agent *agent = get_irq_chip_data(irq);
+ const struct sih *sih = agent->sih;
+
+ int status;
+
+ union {
+ u8 bytes[4];
+ u32 word;
+ } imr;
+
+ if (agent->imr_change_pending) {
+ /* byte[0] gets overwritten as we write ... */
+ imr.word = cpu_to_le32(agent->imr << 8);
+
+ /* write the whole mask ... simpler than subsetting it */
+ status = twl_i2c_write(sih->module, imr.bytes,
+ sih->mask[irq_line].imr_offset, sih->bytes_ixr);
+ if (status)
+ pr_err("twl4030: %s, %s --> %d\n", __func__,
+ "write", status);
+ agent->imr_change_pending = false;
+ }
+
+ if (agent->edge_change) {
+ u32 edge_change;
+ u8 bytes[6];
+
edge_change = agent->edge_change;
+ agent->edge_change = 0;

- /* Read, reserving first byte for write scratch. Yes, this
+ /*
+ * Read, reserving first byte for write scratch. Yes, this
* could be cached for some speedup ... but be careful about
* any processor on the other IRQ line, EDR registers are
* shared.
@@ -550,7 +550,6 @@ static int twl4030_sih_set_type(unsigned irq, unsigned trigger)
if (!d) {
pr_err("twl4030: Invalid IRQ: %d\n",
i + agent->irq_base);
- status = -ENODEV;
goto out;
}

@@ -576,8 +575,6 @@ static int twl4030_sih_set_type(unsigned irq, unsigned trigger)

out:
mutex_unlock(&agent->irq_lock);
-
- return status;
}

static struct irq_chip twl4030_sih_irq_chip = {
@@ -585,6 +582,8 @@ static struct irq_chip twl4030_sih_irq_chip = {
.mask = twl4030_sih_mask,
.unmask = twl4030_sih_unmask,
.set_type = twl4030_sih_set_type,
+ .bus_lock = twl4030_sih_bus_lock,
+ .bus_sync_unlock = twl4030_sih_bus_sync_unlock,
};

/*----------------------------------------------------------------------*/
--
1.7.3.4.598.g85356
--
balbi


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