linux-kernel - [PATCH 1/2] mmc: sdhci: set bus voltage before enabling bus power

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Message-ID: <1446825570-30029-2-git-send-email-ludovic.desroches@atmel.com>
Date:	Fri, 6 Nov 2015 16:59:29 +0100
From:	Ludovic Desroches <ludovic.desroches@...el.com>
To:	<ulf.hansson@...aro.org>, <nicolas.ferre@...el.com>,
	<alexandre.belloni@...e-electrons.com>
CC:	<linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<plagnioj@...osoft.com>, <linux-arm-kernel@...ts.infradead.org>,
	<devicetree@...r.kernel.org>, <pierre.samat@...el.com>,
	Ludovic Desroches <ludovic.desroches@...el.com>
Subject: [PATCH 1/2] mmc: sdhci: set bus voltage before enabling bus power

When there is a vmmc regulator, only SD Bus Power is set to 1 in the
Power Control Register. It means SD Bus Voltage Select field is set to 0
that is a reserved value. The SD Host Controller specification says:
'SD Bus Power: Before setting this bit, the SD Host Driver shall set SD
Bus Voltage Select.' and 'If the Host Driver selects an unsupported
voltage in the SD B?us Voltage Select field, the Host Controller may
ignore writes to SD Bus Power and keep its value at zero."

Having an external regulator means the SD Bus Voltage Select is useless
but if the Host Controller strictly follows the specification then we
need to set a valid value.

Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
---
 drivers/mmc/host/sdhci.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index ac97b46..0cfd7b2 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1278,13 +1278,6 @@ static void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
 		spin_unlock_irq(&host->lock);
 		mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, vdd);
 		spin_lock_irq(&host->lock);
-
-		if (mode != MMC_POWER_OFF)
-			sdhci_writeb(host, SDHCI_POWER_ON, SDHCI_POWER_CONTROL);
-		else
-			sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
-
-		return;
 	}
 
 	if (mode != MMC_POWER_OFF) {
-- 
2.5.0

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