[PATCH v3 0/4] HS400 and HS400ES support for Exynos DW-MMC drivers

[PATCH v3 0/4] HS400 and HS400ES support for Exynos DW-MMC drivers

[Kaustabh Chakraborty]

Since upstream dts version v7.0+, Exynos 7870 devices have an explicit
`bus-width = <8>` property. This results in the U-Boot driver trying to
initialize the HS400 mode, which appears to fail. The HS400 support
added in the DW-MMC Exynos driver appears to have an incomplete init
sequence.

This patch series adds the missing pieces to enable HS400 support, and
additionally adds support for HS400ES too.

The last patch in the series also enables HS400ES support in the
exynos-mobile defconfig.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
---
Changes in v3:
- added review trailers
- Link to v2: https://patch.msgid.link/20260503-dwmmc-exynos-hs400-es-v2-0-3ff1526142a7@disroot.org

Changes in v2:
- added config guard for calls to exynos_config_hs400() (Henrik Grimler)
- Link to v1: https://patch.msgid.link/20260427-dwmmc-exynos-hs400-es-v1-0-3495df40a9ac@disroot.org

To: Peng Fan <peng.fan@nxp.com>
To: Kaustabh Chakraborty <kauschluss@disroot.org>
To: u-boot@lists.denx.de
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Sam Protsenko <semen.protsenko@linaro.org>
Cc: Anand Moon <linux.amoon@gmail.com>
Cc: Lukas Timmermann <uboot@timmermann.space>
Cc: Henrik Grimler <henrik@grimler.se>

---
Kaustabh Chakraborty (4):
      mmc: exynos_dw_mmc: add proper init sequence for HS400 support
      mmc: dw_mmc: setup set_enhanced_strobe ops in driver
      mmc: exynos_dw_mmc: add support for HS400ES
      configs: exynos-mobile: enable support for HS400ES in MMC driver

 arch/arm/mach-exynos/include/mach/dwmmc.h |  5 ++
 configs/exynos-mobile_defconfig           |  1 +
 drivers/mmc/dw_mmc.c                      | 19 +++++++
 drivers/mmc/exynos_dw_mmc.c               | 90 ++++++++++++++++++++++++++++++-
 include/dwmmc.h                           | 10 ++++
 5 files changed, 123 insertions(+), 2 deletions(-)
---
base-commit: 3cdce049f90d77c3f9221f1eb73922384c8972c3
change-id: 20260427-dwmmc-exynos-hs400-es-b77009a808ce

Best regards,
--  
Kaustabh Chakraborty <kauschluss@disroot.org>

[PATCH v3 1/4] mmc: exynos_dw_mmc: add proper init sequence for HS400 support

[Kaustabh Chakraborty]

HS400 support was added, but configuration necessary for HS400 support
was left out. Add necessary changes, which includes:
- Device tree properties, such as "samsung,dw-mshc-hs400-timing" and
  "samsung,read-strobe-delay", which function as per dt-bindings.
- Registers related to HS400, which are necessary to enable HS400+ support.
- Appropriate timing tunings for the HS400 mode.

Note that these changes are loosely based off of its Linux kernel
counterpart.

Fixes: bbe3b9fa0922 ("mmc: exynos_dw_mmc: add support for MMC HS200 and HS400 modes")
Reviewed-by: Henrik Grimler <henrik@grimler.se>
Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
---
 arch/arm/mach-exynos/include/mach/dwmmc.h |  5 ++
 drivers/mmc/exynos_dw_mmc.c               | 81 +++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/arch/arm/mach-exynos/include/mach/dwmmc.h b/arch/arm/mach-exynos/include/mach/dwmmc.h
index 4432deedef7..50081326c25 100644
--- a/arch/arm/mach-exynos/include/mach/dwmmc.h
+++ b/arch/arm/mach-exynos/include/mach/dwmmc.h
@@ -15,6 +15,11 @@
 #define DWMCI_SET_DRV_CLK(x)		((x) << 16)
 #define DWMCI_SET_DIV_RATIO(x)		((x) << 24)
 
+/* HS400 Related Registers */
+#define DWMCI_HS400_DQS_EN		0x180
+#define DWMCI_HS400_ASYNC_FIFO_CTRL	0x184
+#define DWMCI_HS400_DLINE_CTRL		0x188
+
 /* Protector Register */
 #define DWMCI_EMMCP_BASE		0x1000
 #define EMMCP_MPSECURITY		(DWMCI_EMMCP_BASE + 0x0010)
diff --git a/drivers/mmc/exynos_dw_mmc.c b/drivers/mmc/exynos_dw_mmc.c
index 7ccd113bd79..6558cdc803d 100644
--- a/drivers/mmc/exynos_dw_mmc.c
+++ b/drivers/mmc/exynos_dw_mmc.c
@@ -8,6 +8,7 @@
 #include <dwmmc.h>
 #include <asm/global_data.h>
 #include <malloc.h>
+#include <mmc.h>
 #include <errno.h>
 #include <asm/arch/dwmmc.h>
 #include <asm/arch/clk.h>
@@ -30,6 +31,14 @@
 #define CLKSEL_UP_SAMPLE(x, y)		(((x) & ~CLKSEL_CCLK_SAMPLE(7)) | \
 					 CLKSEL_CCLK_SAMPLE(y))
 
+/* RCLK_EN register defines */
+#define DATA_STROBE_EN			BIT(0)
+#define AXI_NON_BLOCKING_WR	BIT(7)
+
+/* DLINE_CTRL register defines */
+#define DQS_CTRL_RD_DELAY(x, y)		(((x) & ~0x3FF) | ((y) & 0x3FF))
+#define DQS_CTRL_GET_RD_DELAY(x)	((x) & 0x3FF)
+
 /**
  * DOC: Quirk flags for different Exynos DW MMC blocks
  *
@@ -71,6 +80,11 @@ struct dwmci_exynos_priv_data {
 	struct clk clk;
 	u32 sdr_timing;
 	u32 ddr_timing;
+	u32 hs400_timing;
+	u32 tuned_sample;
+	u32 dqs_delay;
+	u32 saved_dqs_en;
+	u32 saved_strobe_ctrl;
 	const struct exynos_dwmmc_variant *chip;
 };
 
@@ -162,6 +176,27 @@ static u8 exynos_dwmmc_get_ciu_div(struct dwmci_host *host)
 				& DWMCI_DIVRATIO_MASK) + 1;
 }
 
+static void exynos_config_hs400(struct dwmci_host *host, enum bus_mode mode)
+{
+	struct dwmci_exynos_priv_data *priv = exynos_dwmmc_get_priv(host);
+	u32 dqs, strobe;
+
+	dqs = priv->saved_dqs_en;
+	strobe = priv->saved_strobe_ctrl;
+
+	switch (mode) {
+	case MMC_HS_400:
+		dqs |= DATA_STROBE_EN;
+		strobe = DQS_CTRL_RD_DELAY(strobe, priv->dqs_delay);
+		break;
+	default:
+		dqs &= ~DATA_STROBE_EN;
+	}
+
+	dwmci_writel(host, DWMCI_HS400_DQS_EN, dqs);
+	dwmci_writel(host, DWMCI_HS400_DLINE_CTRL, strobe);
+}
+
 /* Configure CLKSEL register with chosen timing values */
 static int exynos_dwmci_clksel(struct dwmci_host *host)
 {
@@ -170,6 +205,9 @@ static int exynos_dwmci_clksel(struct dwmci_host *host)
 	u32 timing;
 
 	switch (host->mmc->selected_mode) {
+	case MMC_HS_400:
+		timing = CLKSEL_UP_SAMPLE(priv->hs400_timing, priv->tuned_sample);
+		break;
 	case MMC_DDR_52:
 		timing = priv->ddr_timing;
 		break;
@@ -186,6 +224,9 @@ static int exynos_dwmci_clksel(struct dwmci_host *host)
 
 	dwmci_writel(host, priv->chip->clksel, timing);
 
+	if (CONFIG_IS_ENABLED(MMC_HS400_SUPPORT))
+		exynos_config_hs400(host, host->mmc->selected_mode);
+
 	return 0;
 }
 
@@ -223,6 +264,16 @@ static void exynos_dwmci_board_init(struct dwmci_host *host)
 {
 	struct dwmci_exynos_priv_data *priv = exynos_dwmmc_get_priv(host);
 
+	if (CONFIG_IS_ENABLED(MMC_HS400_SUPPORT)) {
+		priv->saved_strobe_ctrl = dwmci_readl(host, DWMCI_HS400_DLINE_CTRL);
+		priv->saved_dqs_en = dwmci_readl(host, DWMCI_HS400_DQS_EN);
+		priv->saved_dqs_en |= AXI_NON_BLOCKING_WR;
+		dwmci_writel(host, DWMCI_HS400_DQS_EN, priv->saved_dqs_en);
+		if (!priv->dqs_delay)
+			priv->dqs_delay =
+				DQS_CTRL_GET_RD_DELAY(priv->saved_strobe_ctrl);
+	}
+
 	if (priv->chip->quirks & DWMCI_QUIRK_DISABLE_SMU) {
 		dwmci_writel(host, EMMCP_MPSBEGIN0, 0);
 		dwmci_writel(host, EMMCP_SEND0, 0);
@@ -319,6 +370,22 @@ static int exynos_dwmmc_of_to_plat(struct udevice *dev)
 				   DWMCI_SET_DIV_RATIO(div);
 	}
 
+	err = dev_read_u32_array(dev, "samsung,dw-mshc-hs400-timing", timing, 2);
+	if (err) {
+		debug("DWMMC%d: Can't get hs400-timings, using ddr-timings\n",
+		      host->dev_index);
+		priv->hs400_timing = priv->ddr_timing;
+	} else {
+		priv->hs400_timing = DWMCI_SET_SAMPLE_CLK(timing[0]) |
+				     DWMCI_SET_DRV_CLK(timing[1]) |
+				     DWMCI_SET_DIV_RATIO(1);
+		if (dev_read_u32(dev, "samsung,read-strobe-delay", &priv->dqs_delay)) {
+			priv->dqs_delay = 0;
+			debug("DWMMC%d: read-strobe-delay is not found, assuming usage of default value\n",
+			      host->dev_index);
+		}
+	}
+
 	host->buswidth = dev_read_u32_default(dev, "bus-width", 4);
 	host->fifo_depth = dev_read_u32_default(dev, "fifo-depth", 0);
 	host->bus_hz = dev_read_u32_default(dev, "clock-frequency", 0);
@@ -356,6 +423,16 @@ static int exynos_dwmmc_get_best_clksmpl(u8 candidates)
 	return -EIO;
 }
 
+static int dw_mci_exynos_prepare_hs400_tuning(struct dwmci_host *host)
+{
+	struct dwmci_exynos_priv_data *priv = exynos_dwmmc_get_priv(host);
+
+	dwmci_writel(host, priv->chip->clksel, priv->hs400_timing);
+	host->bus_hz = exynos_dwmci_get_clk(host, host->clock);
+
+	return 0;
+}
+
 static int exynos_dwmmc_execute_tuning(struct udevice *dev, u32 opcode)
 {
 	struct dwmci_exynos_priv_data *priv = dev_get_priv(dev);
@@ -365,6 +442,9 @@ static int exynos_dwmmc_execute_tuning(struct udevice *dev, u32 opcode)
 	u32 clksel;
 	int ret;
 
+	if (mmc->hs400_tuning)
+		dw_mci_exynos_prepare_hs400_tuning(host);
+
 	clksel = dwmci_readl(host, priv->chip->clksel);
 	start_smpl = CLKSEL_CCLK_SAMPLE(clksel);
 
@@ -387,6 +467,7 @@ static int exynos_dwmmc_execute_tuning(struct udevice *dev, u32 opcode)
 		return ret;
 	}
 
+	priv->tuned_sample = ret;
 	dwmci_writel(host, priv->chip->clksel, CLKSEL_UP_SAMPLE(clksel, ret));
 
 	return 0;

-- 
2.53.0

[PATCH v3 2/4] mmc: dw_mmc: setup set_enhanced_strobe ops in driver

[Kaustabh Chakraborty]

At the end of HS400ES initialization by the core mmc driver,
mmc_set_enhanced_strobe() is called. This expects the host driver to
have an ops function for it.

The DW-MMC driver does not have it, thus the call fails with -ENOSUPP.
Add the ops function to allow control to be passed to the host side.

Since DW-MMC driver implementation depends on the platform, the above
ops function is made to pass its control to the implementation-specific
function available in the platform-specific driver.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
---
 drivers/mmc/dw_mmc.c | 19 +++++++++++++++++++
 include/dwmmc.h      | 10 ++++++++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
index d9c05b223d5..0a245d72881 100644
--- a/drivers/mmc/dw_mmc.c
+++ b/drivers/mmc/dw_mmc.c
@@ -730,6 +730,19 @@ static int dwmci_init(struct mmc *mmc)
 	return 0;
 }
 
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+static int dwmci_set_enhanced_strobe(struct udevice *dev)
+{
+	struct mmc *mmc = mmc_get_mmc_dev(dev);
+	struct dwmci_host *host = mmc->priv;
+
+	if (host && host->set_enhanced_strobe)
+		return host->set_enhanced_strobe(host);
+
+	return 0;
+}
+#endif
+
 #if CONFIG_IS_ENABLED(DM_MMC)
 int dwmci_probe(struct udevice *dev)
 {
@@ -741,6 +754,9 @@ int dwmci_probe(struct udevice *dev)
 const struct dm_mmc_ops dm_dwmci_ops = {
 	.send_cmd	= dwmci_send_cmd,
 	.set_ios	= dwmci_set_ios,
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+	.set_enhanced_strobe = dwmci_set_enhanced_strobe,
+#endif
 };
 
 #else
@@ -748,6 +764,9 @@ static const struct mmc_ops dwmci_ops = {
 	.send_cmd	= dwmci_send_cmd,
 	.set_ios	= dwmci_set_ios,
 	.init		= dwmci_init,
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+	.set_enhanced_strobe = dwmci_set_enhanced_strobe,
+#endif
 };
 #endif
 
diff --git a/include/dwmmc.h b/include/dwmmc.h
index 7e1a6646518..49488709a82 100644
--- a/include/dwmmc.h
+++ b/include/dwmmc.h
@@ -225,6 +225,16 @@ struct dwmci_host {
 	 * return that value too. Then DWMMC will put itself in bypass mode.
 	 */
 	unsigned int (*get_mmc_clk)(struct dwmci_host *host, uint freq);
+	/**
+	 * @set_enhanced_strobe: (Optional) Platform function to run on enabling
+	 * HS400ES strobe
+	 *
+	 * @host:	DWMMC host
+	 *
+	 * This is used to enable the enhanced strobe for the HS400ES MMC mode.
+	 * The caller invokes this at the end of the HS400ES frequency dance.
+	 */
+	unsigned int (*set_enhanced_strobe)(struct dwmci_host *host);
 
 #ifndef CONFIG_BLK
 	struct mmc_config cfg;

-- 
2.53.0

[PATCH v3 3/4] mmc: exynos_dw_mmc: add support for HS400ES

[Kaustabh Chakraborty]

Add support for HS400ES. This is trivial as no new init sequence is
required in the driver, add it to the host driver capabilities, and
direct the HS400ES mode on reusing the HS400 init sequence.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
---
 drivers/mmc/exynos_dw_mmc.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/exynos_dw_mmc.c b/drivers/mmc/exynos_dw_mmc.c
index 6558cdc803d..e0c4bbb17cc 100644
--- a/drivers/mmc/exynos_dw_mmc.c
+++ b/drivers/mmc/exynos_dw_mmc.c
@@ -185,6 +185,7 @@ static void exynos_config_hs400(struct dwmci_host *host, enum bus_mode mode)
 	strobe = priv->saved_strobe_ctrl;
 
 	switch (mode) {
+	case MMC_HS_400_ES:
 	case MMC_HS_400:
 		dqs |= DATA_STROBE_EN;
 		strobe = DQS_CTRL_RD_DELAY(strobe, priv->dqs_delay);
@@ -205,6 +206,7 @@ static int exynos_dwmci_clksel(struct dwmci_host *host)
 	u32 timing;
 
 	switch (host->mmc->selected_mode) {
+	case MMC_HS_400_ES:
 	case MMC_HS_400:
 		timing = CLKSEL_UP_SAMPLE(priv->hs400_timing, priv->tuned_sample);
 		break;
@@ -224,7 +226,8 @@ static int exynos_dwmci_clksel(struct dwmci_host *host)
 
 	dwmci_writel(host, priv->chip->clksel, timing);
 
-	if (CONFIG_IS_ENABLED(MMC_HS400_SUPPORT))
+	if (CONFIG_IS_ENABLED(MMC_HS400_SUPPORT) ||
+	    CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT))
 		exynos_config_hs400(host, host->mmc->selected_mode);
 
 	return 0;
@@ -239,7 +242,8 @@ static unsigned int exynos_dwmci_get_clk(struct dwmci_host *host, uint freq)
 	/* Should be double rate for DDR or HS mode */
 	if ((host->mmc->selected_mode == MMC_DDR_52 &&
 	     host->mmc->bus_width == 8) ||
-	    host->mmc->selected_mode == MMC_HS_400) {
+	    host->mmc->selected_mode == MMC_HS_400 ||
+	    host->mmc->selected_mode == MMC_HS_400_ES) {
 		freq *= 2;
 	}
 
@@ -264,7 +268,8 @@ static void exynos_dwmci_board_init(struct dwmci_host *host)
 {
 	struct dwmci_exynos_priv_data *priv = exynos_dwmmc_get_priv(host);
 
-	if (CONFIG_IS_ENABLED(MMC_HS400_SUPPORT)) {
+	if (CONFIG_IS_ENABLED(MMC_HS400_SUPPORT) ||
+	    CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)) {
 		priv->saved_strobe_ctrl = dwmci_readl(host, DWMCI_HS400_DLINE_CTRL);
 		priv->saved_dqs_en = dwmci_readl(host, DWMCI_HS400_DQS_EN);
 		priv->saved_dqs_en |= AXI_NON_BLOCKING_WR;
@@ -522,7 +527,7 @@ static int exynos_dwmmc_probe(struct udevice *dev)
 	host->name = dev->name;
 	host->board_init = exynos_dwmci_board_init;
 	host->caps = MMC_MODE_DDR_52MHz | MMC_MODE_HS200 | MMC_MODE_HS400 |
-		     UHS_CAPS;
+		     MMC_MODE_HS400_ES | UHS_CAPS;
 	host->clksel = exynos_dwmci_clksel;
 	host->get_mmc_clk = exynos_dwmci_get_clk;
 

-- 
2.53.0

[PATCH v3 4/4] configs: exynos-mobile: enable support for HS400ES in MMC driver

[Kaustabh Chakraborty]

MMC0 in Exynos7870 devices (supported by this board variant) can be
initialized in HS400ES mode. Enable the respective config option.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
---
 configs/exynos-mobile_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/configs/exynos-mobile_defconfig b/configs/exynos-mobile_defconfig
index 45ab998bb45..0272222e608 100644
--- a/configs/exynos-mobile_defconfig
+++ b/configs/exynos-mobile_defconfig
@@ -47,6 +47,7 @@ CONFIG_MISC=y
 CONFIG_MMC_BROKEN_CD=y
 CONFIG_MMC_IO_VOLTAGE=y
 CONFIG_MMC_UHS_SUPPORT=y
+CONFIG_MMC_HS400_ES_SUPPORT=y
 CONFIG_MMC_HS400_SUPPORT=y
 CONFIG_MMC_DW=y
 CONFIG_PHY=y

-- 
2.53.0

Re: [PATCH v3 0/4] HS400 and HS400ES support for Exynos DW-MMC drivers

[Kaustabh Chakraborty]

On 2026-06-13 13:13 +05:30, Kaustabh Chakraborty wrote:
> Since upstream dts version v7.0+, Exynos 7870 devices have an explicit
> `bus-width = <8>` property. This results in the U-Boot driver trying to
> initialize the HS400 mode, which appears to fail. The HS400 support
> added in the DW-MMC Exynos driver appears to have an incomplete init
> sequence.
>
> This patch series adds the missing pieces to enable HS400 support, and
> additionally adds support for HS400ES too.
>
> The last patch in the series also enables HS400ES support in the
> exynos-mobile defconfig.
>
> Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>

Just a bump; failure to pull this series would render upstream stable
U-Boot v2026.07 on the Samsung Galaxy J7 Prime (samsung-on7xelte) unable
to load any operating system due to lack of a storage device.

As of yet I do not see the series in master, next, nor in the MMC Custodian tree.

RE: [PATCH v3 0/4] HS400 and HS400ES support for Exynos DW-MMC drivers

[Peng Fan]

> Subject: Re: [PATCH v3 0/4] HS400 and HS400ES support for Exynos
> DW-MMC drivers
> 
> On 2026-06-13 13:13 +05:30, Kaustabh Chakraborty wrote:
> > Since upstream dts version v7.0+, Exynos 7870 devices have an
> explicit
> > `bus-width = <8>` property. This results in the U-Boot driver trying
> > to initialize the HS400 mode, which appears to fail. The HS400
> support
> > added in the DW-MMC Exynos driver appears to have an incomplete
> init
> > sequence.
> >
> > This patch series adds the missing pieces to enable HS400 support,
> and
> > additionally adds support for HS400ES too.
> >
> > The last patch in the series also enables HS400ES support in the
> > exynos-mobile defconfig.
> >
> > Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
> 
> Just a bump; failure to pull this series would render upstream stable U-
> Boot v2026.07 on the Samsung Galaxy J7 Prime (samsung-on7xelte)
> unable to load any operating system due to lack of a storage device.
> 
> As of yet I do not see the series in master, next, nor in the MMC
> Custodian tree.

I see this patchset was delegated to prom, not mmc maintainer.
Minkyu may pick it up?

https://patchwork.ozlabs.org/project/uboot/list/?submitter=88698&param=state&order=submitter

Regards
Peng