linux-kernel - [PATCH 3/3] mfd: arizona: Use new regmap features for manual register patch

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Date:	Fri, 21 Feb 2014 19:37:12 +0000
From:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:	broonie@...nel.org
Cc:	gregkh@...uxfoundation.org, sameo@...ux.intel.com,
	lee.jones@...aro.org, linux-kernel@...r.kernel.org,
	patches@...nsource.wolfsonmicro.com
Subject: [PATCH 3/3] mfd: arizona: Use new regmap features for manual register patch

On the wm5102 the register patches are applied manually, rather than by
the regmap core. This application is wrapped in calls to
regcache_cache_bypass. However, this is dangerous as other threads may
be accessing the hardware at the same time as the pm_runtime operations
and if they do so during the period whilst cache_bypass is enabled those
writes will miss the cache when they shouldn't.

Apply the register patch using the new regmap_apply_patch function to
avoid this problem. Also remove the call to regcache_cache_bypass from
the hardware patch application as it is unneeded there and creates a
similar window for writes to miss the cache.

Signed-off-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
---
 drivers/mfd/arizona-core.c  |    4 ----
 drivers/mfd/wm5102-tables.c |   19 ++-----------------
 2 files changed, 2 insertions(+), 21 deletions(-)

diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c
index a45aab9..1c3ae57 100644
--- a/drivers/mfd/arizona-core.c
+++ b/drivers/mfd/arizona-core.c
@@ -251,8 +251,6 @@ static int arizona_apply_hardware_patch(struct arizona* arizona)
 	unsigned int fll, sysclk;
 	int ret, err;
 
-	regcache_cache_bypass(arizona->regmap, true);
-
 	/* Cache existing FLL and SYSCLK settings */
 	ret = regmap_read(arizona->regmap, ARIZONA_FLL1_CONTROL_1, &fll);
 	if (ret != 0) {
@@ -322,8 +320,6 @@ err_fll:
 			err);
 	}
 
-	regcache_cache_bypass(arizona->regmap, false);
-
 	if (ret != 0)
 		return ret;
 	else
diff --git a/drivers/mfd/wm5102-tables.c b/drivers/mfd/wm5102-tables.c
index 1e9a4b2..237020d 100644
--- a/drivers/mfd/wm5102-tables.c
+++ b/drivers/mfd/wm5102-tables.c
@@ -80,8 +80,7 @@ static const struct reg_default wm5102_revb_patch[] = {
 int wm5102_patch(struct arizona *arizona)
 {
 	const struct reg_default *wm5102_patch;
-	int ret = 0;
-	int i, patch_size;
+	int patch_size;
 
 	switch (arizona->rev) {
 	case 0:
@@ -92,21 +91,7 @@ int wm5102_patch(struct arizona *arizona)
 		patch_size = ARRAY_SIZE(wm5102_revb_patch);
 	}
 
-	regcache_cache_bypass(arizona->regmap, true);
-
-	for (i = 0; i < patch_size; i++) {
-		ret = regmap_write(arizona->regmap, wm5102_patch[i].reg,
-				   wm5102_patch[i].def);
-		if (ret != 0) {
-			dev_err(arizona->dev, "Failed to write %x = %x: %d\n",
-				wm5102_patch[i].reg, wm5102_patch[i].def, ret);
-			goto out;
-		}
-	}
-
-out:
-	regcache_cache_bypass(arizona->regmap, false);
-	return ret;
+	return regmap_apply_patch(arizona->regmap, wm5102_patch, patch_size);
 }
 
 static const struct regmap_irq wm5102_aod_irqs[ARIZONA_NUM_IRQ] = {
-- 
1.7.2.5

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