linux-kernel - [PATCH 3.16 301/410] mmc: sdhci-pci: Fix S0i3 for Intel BYT-based controllers

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Message-ID: <lsq.1528380321.332017313@decadent.org.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Ulf Hansson" <ulf.hansson@...aro.org>,
        "Adrian Hunter" <adrian.hunter@...el.com>
Subject: [PATCH 3.16 301/410] mmc: sdhci-pci: Fix S0i3 for Intel BYT-based
 controllers

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Adrian Hunter <adrian.hunter@...el.com>

commit f8870ae6e2d6be75b1accc2db981169fdfbea7ab upstream.

Tuning can leave the IP in an active state (Buffer Read Enable bit set)
which prevents the entry to low power states (i.e. S0i3). Data reset will
clear it.

Generally tuning is followed by a data transfer which will anyway sort out
the state, so it is rare that S0i3 is actually prevented.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
[bwh: Backported to 3.16:
 - Drop chnages in ni_byt_sdio_probe_slot(), byt_sd_probe_slot()
 - Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mmc/host/sdhci-pci.c | 35 +++++++++++++++++++++++++++----
 1 file changed, 31 insertions(+), 4 deletions(-)

--- a/drivers/mmc/host/sdhci-pci.c
+++ b/drivers/mmc/host/sdhci-pci.c
@@ -265,8 +265,34 @@ static void sdhci_pci_int_hw_reset(struc
 	usleep_range(300, 1000);
 }
 
+static int intel_execute_tuning(struct mmc_host *mmc, u32 opcode)
+{
+	int err = sdhci_execute_tuning(mmc, opcode);
+	struct sdhci_host *host = mmc_priv(mmc);
+
+	if (err)
+		return err;
+
+	/*
+	 * Tuning can leave the IP in an active state (Buffer Read Enable bit
+	 * set) which prevents the entry to low power states (i.e. S0i3). Data
+	 * reset will clear it.
+	 */
+	sdhci_reset(host, SDHCI_RESET_DATA);
+
+	return 0;
+}
+
+static void byt_probe_slot(struct sdhci_pci_slot *slot)
+{
+	struct mmc_host_ops *ops = &slot->host->mmc_host_ops;
+
+	ops->execute_tuning = intel_execute_tuning;
+}
+
 static int byt_emmc_probe_slot(struct sdhci_pci_slot *slot)
 {
+	byt_probe_slot(slot);
 	slot->host->mmc->caps |= MMC_CAP_8_BIT_DATA | MMC_CAP_NONREMOVABLE |
 				 MMC_CAP_HW_RESET;
 	slot->host->mmc->caps2 |= MMC_CAP2_HC_ERASE_SZ;
@@ -278,6 +304,7 @@ static int byt_emmc_probe_slot(struct sd
 
 static int byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
 {
+	byt_probe_slot(slot);
 	slot->host->mmc->caps |= MMC_CAP_POWER_OFF_CARD | MMC_CAP_NONREMOVABLE;
 	return 0;
 }