linux-kernel - [PATCH v2] mmc: rtsx: add 74 Clocks in power on flow

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Date:   Wed, 2 Mar 2022 09:43:01 +0000
From:   Ricky WU <ricky_wu@...ltek.com>
To:     "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "tommyhebb@...il.com" <tommyhebb@...il.com>,
        "kai.heng.feng@...onical.com" <kai.heng.feng@...onical.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Ricky WU <ricky_wu@...ltek.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] mmc: rtsx: add 74 Clocks in power on flow

SD spec definition:
"Host provides at least 74 Clocks before issuing first command"
After 1ms for the voltage stable then start issuing the Clock signals

if POWER STATE is
MMC_POWER_OFF to MMC_POWER_UP to issue Clock signal to card
MMC_POWER_UP to MMC_POWER_ON to stop issuing signal to card

Signed-off-by: Ricky Wu <ricky_wu@...ltek.com>
---
v2:
modify commit message
move mdelay(5) to host->power_delay_ms
replace host->power_state with host->prev_power_state
---
 drivers/mmc/host/rtsx_pci_sdmmc.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
index 2a3f14afe9f8..d26803d3f4ca 100644
--- a/drivers/mmc/host/rtsx_pci_sdmmc.c
+++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
@@ -38,10 +38,7 @@ struct realtek_pci_sdmmc {
 	bool			double_clk;
 	bool			eject;
 	bool			initial_mode;
-	int			power_state;
-#define SDMMC_POWER_ON		1
-#define SDMMC_POWER_OFF		0
-
+	int			prev_power_state;
 	int			sg_count;
 	s32			cookie;
 	int			cookie_sg_count;
@@ -909,7 +906,7 @@ static int sd_set_bus_width(struct realtek_pci_sdmmc *host,
 	return err;
 }
 
-static int sd_power_on(struct realtek_pci_sdmmc *host)
+static int sd_power_on(struct realtek_pci_sdmmc *host, unsigned char power_mode)
 {
 	struct rtsx_pcr *pcr = host->pcr;
 	struct mmc_host *mmc = host->mmc;
@@ -917,9 +914,14 @@ static int sd_power_on(struct realtek_pci_sdmmc *host)
 	u32 val;
 	u8 test_mode;
 
-	if (host->power_state == SDMMC_POWER_ON)
+	if (host->prev_power_state == MMC_POWER_ON)
 		return 0;
 
+	if (host->prev_power_state == MMC_POWER_UP) {
+		rtsx_pci_write_register(pcr, SD_BUS_STAT, SD_CLK_TOGGLE_EN, 0);
+		goto finish;
+	}
+
 	msleep(100);
 
 	rtsx_pci_init_cmd(pcr);
@@ -940,10 +942,15 @@ static int sd_power_on(struct realtek_pci_sdmmc *host)
 	if (err < 0)
 		return err;
 
+	mdelay(1);
+
 	err = rtsx_pci_write_register(pcr, CARD_OE, SD_OUTPUT_EN, SD_OUTPUT_EN);
 	if (err < 0)
 		return err;
 
+	/* send at least 74 clocks */
+	rtsx_pci_write_register(pcr, SD_BUS_STAT, SD_CLK_TOGGLE_EN, SD_CLK_TOGGLE_EN);
+
 	if (PCI_PID(pcr) == PID_5261) {
 		/*
 		 * If test mode is set switch to SD Express mandatorily,
@@ -968,7 +975,8 @@ static int sd_power_on(struct realtek_pci_sdmmc *host)
 		}
 	}
 
-	host->power_state = SDMMC_POWER_ON;
+finish:
+	host->prev_power_state = power_mode;
 	return 0;
 }
 
@@ -977,7 +985,7 @@ static int sd_power_off(struct realtek_pci_sdmmc *host)
 	struct rtsx_pcr *pcr = host->pcr;
 	int err;
 
-	host->power_state = SDMMC_POWER_OFF;
+	host->prev_power_state = MMC_POWER_OFF;
 
 	rtsx_pci_init_cmd(pcr);
 
@@ -1003,7 +1011,7 @@ static int sd_set_power_mode(struct realtek_pci_sdmmc *host,
 	if (power_mode == MMC_POWER_OFF)
 		err = sd_power_off(host);
 	else
-		err = sd_power_on(host);
+		err = sd_power_on(host, power_mode);
 
 	return err;
 }
@@ -1506,10 +1514,11 @@ static int rtsx_pci_sdmmc_drv_probe(struct platform_device *pdev)
 
 	host = mmc_priv(mmc);
 	host->pcr = pcr;
+	mmc->ios.power_delay_ms = 5;
 	host->mmc = mmc;
 	host->pdev = pdev;
 	host->cookie = -1;
-	host->power_state = SDMMC_POWER_OFF;
+	host->prev_power_state = MMC_POWER_OFF;
 	INIT_WORK(&host->work, sd_request);
 	platform_set_drvdata(pdev, host);
 	pcr->slots[RTSX_SD_CARD].p_dev = pdev;
-- 
2.25.1