linux-kernel - [PATCH V9 12/23] mmc: sdhci-uhs2: skip signal_voltage

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Message-Id: <20230721101349.12387-13-victorshihgli@gmail.com>
Date:   Fri, 21 Jul 2023 18:13:38 +0800
From:   Victor Shih <victorshihgli@...il.com>
To:     ulf.hansson@...aro.org, adrian.hunter@...el.com
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        benchuanggli@...il.com, HL.Liu@...esyslogic.com.tw,
        Greg.tu@...esyslogic.com.tw, takahiro.akashi@...aro.org,
        dlunev@...omium.org, Victor Shih <victorshihgli@...il.com>,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>,
        Victor Shih <victor.shih@...esyslogic.com.tw>
Subject: [PATCH V9 12/23] mmc: sdhci-uhs2: skip signal_voltage_switch()

From: Victor Shih <victor.shih@...esyslogic.com.tw>

For UHS2, the signal voltage is supplied by vdd2 which is already 1.8v,
so no voltage switch required.

Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
Signed-off-by: Victor Shih <victor.shih@...esyslogic.com.tw>
---

Updates in V5:
 - Use sdhci_uhs2_mode() to simplify code in
   sdhci_uhs2_start_signal_voltage_switch().

---

 drivers/mmc/host/sdhci-uhs2.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index fc37a34629c2..92fb69b7e209 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -142,6 +142,27 @@ static void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode, un
 	}
 }
 
+/*****************************************************************************\
+ *                                                                           *
+ * MMC callbacks                                                             *
+ *                                                                           *
+\*****************************************************************************/
+
+static int sdhci_uhs2_start_signal_voltage_switch(struct mmc_host *mmc,
+						  struct mmc_ios *ios)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+
+	/*
+	 * For UHS2, the signal voltage is supplied by vdd2 which is
+	 * already 1.8v so no voltage switch required.
+	 */
+	if (sdhci_uhs2_mode(host))
+		return 0;
+
+	return sdhci_start_signal_voltage_switch(mmc, ios);
+}
+
 /*****************************************************************************\
  *                                                                           *
  * Driver init/exit                                                          *
@@ -150,6 +171,9 @@ static void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode, un
 
 static int sdhci_uhs2_host_ops_init(struct sdhci_host *host)
 {
+	host->mmc_host_ops.start_signal_voltage_switch =
+		sdhci_uhs2_start_signal_voltage_switch;
+
 	return 0;
 }
 
-- 
2.25.1