linux-kernel - [PATCH 1/2] MMC/pxamci: workaround regulator framework bugs

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Message-Id: <1246057668.10360.316.camel@brutus>
Date:	Fri, 26 Jun 2009 20:07:48 -0300
From:	Daniel Ribeiro <drwyrm@...il.com>
To:	Pierre Ossman <pierre@...man.eu>,
	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	Eric Miao <eric.y.miao@...il.com>,
	Mark Brown <broonie@...ena.org.uk>,
	openezx-devel <openezx-devel@...ts.openezx.org>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	Liam Girdwood <lrg@...mlogic.co.uk>,
	linux-arm-kernel <linux-arm-kernel@...ts.arm.linux.org.uk>
Subject: [PATCH 1/2] MMC/pxamci: workaround regulator framework bugs

The voltage regulator framework can't sanely deal with voltage
regulators which are left enabled by the bootloader. We workaround this
by forcing an enable()/disable() pair so it has a sane use_count.

Signed-off-by: Daniel Ribeiro <drwyrm@...il.com>

---
 drivers/mmc/host/pxamci.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/pxamci.c b/drivers/mmc/host/pxamci.c
index d7d7109..20fb3da 100644
--- a/drivers/mmc/host/pxamci.c
+++ b/drivers/mmc/host/pxamci.c
@@ -80,6 +80,18 @@ static inline void pxamci_init_ocr(struct pxamci_host *host)
 	if (IS_ERR(host->vcc))
 		host->vcc = NULL;
 	else {
+		/*
+		 * When the bootloader leaves a supply active, it's
+		 * initialized with zero usecount ... and we can't
+		 * disable it without first enabling it.  Until the
+		 * framework is fixed, we need a workaround like this
+		 * (which is safe for MMC, but not in general).
+		 */
+		if (regulator_is_enabled(host->vcc) > 0) {
+			regulator_enable(host->vcc);
+			regulator_disable(host->vcc);
+		}
+
 		host->mmc->ocr_avail = mmc_regulator_get_ocrmask(host->vcc);
 		if (host->pdata && host->pdata->ocr_mask)
 			dev_warn(mmc_dev(host->mmc),
-- 
tg: (87da0bf..) mmc/workaround-regulator-bugs (depends on: mmc/pxamci-regulator-support)

-- 
Daniel Ribeiro

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