[PATCH 0/7] mmc: spacemit: improve clock and tuning logic

[PATCH 0/7] mmc: spacemit: improve clock and tuning logic

[Yixun Lan]

This series includes some bug fixes and improvement to
SpacemiT SDHCI driver, which relate to pinctrl, PHY,
clock, tuning logic. Most of them are quite independent,
but put them together here for people to easy review.

Signed-off-by: Yixun Lan <dlan@kernel.org>
---
Long Wan (6):
      mmc: sdhci-of-k1: no pinctrl state switching
      mmc: sdhci-of-k1: configure PHY mode
      mmc: sdhci-of-k1: Improve power control
      mmc: sdhci-of-k1: Use finest delay granularity for RX tuning
      mmc: sdhci-of-k1: Improve RX tuning window
      mmc: sdhci-of-k1: Implement SD clock gating for voltage switch

Yixun Lan (1):
      mmc: sdhci-of-k1: drop duplicated voltage settings

 drivers/mmc/host/sdhci-of-k1.c | 80 ++++++++++++++++++++++++++++++++----------
 1 file changed, 61 insertions(+), 19 deletions(-)
---
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
change-id: 20260901-07-k3-sdhci-fix-ce577d1db7b6

Best regards,
--  
Yixun Lan <dlan@kernel.org>


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[PATCH 1/7] mmc: sdhci-of-k1: no pinctrl state switching

[Yixun Lan]

From: Long Wan <long.wan@linux.spacemit.com>

No need to switch pinctrl state if the SDHCI controller only support 1.8v
IO voltage which DT will only provide a "default" pinctrl state, otherwise
function pinctrl_select_state() will trigger a NULL pointer error.

Fixes: 00a97fc57c09 ("mmc: sdhci-of-k1: add regulator and pinctrl voltage switching support")
Signed-off-by: Long Wan <long.wan@linux.spacemit.com>
Signed-off-by: Yixun Lan <dlan@kernel.org>
---
 drivers/mmc/host/sdhci-of-k1.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index 37b0911e7cf2..0916340d3265 100644
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -407,7 +407,8 @@ static int spacemit_sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
 	if (ret)
 		return ret;
 
-	if (!sdhst->pinctrl)
+	/* No pinctrl or no "uhs" state */
+	if (!sdhst->pinctrl || !sdhst->pinctrl_uhs)
 		return 0;
 
 	/* Select appropriate pinctrl state based on signal voltage */

-- 
2.55.0


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[PATCH 2/7] mmc: sdhci-of-k1: drop duplicated voltage settings

[Yixun Lan]

No need to set 1.8V Signal for non-SDIO hosts, it will duplicate
what sdhci_start_signal_voltage_switch() already handled there.

Fixes: e5502d15b0f3 ("mmc: sdhci-of-k1: add support for SpacemiT K1 SoC")
Signed-off-by: Yixun Lan <dlan@kernel.org>
---
 drivers/mmc/host/sdhci-of-k1.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index 0916340d3265..afd9536f2368 100644
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -195,9 +195,6 @@ static void spacemit_sdhci_set_uhs_signaling(struct sdhci_host *host, unsigned i
 		spacemit_sdhci_setbits(host, SDHC_MMC_HS400, SPACEMIT_SDHC_MMC_CTRL_REG);
 
 	sdhci_set_uhs_signaling(host, timing);
-
-	if (!(host->mmc->caps2 & MMC_CAP2_NO_SDIO))
-		spacemit_sdhci_setbits(host, SDHCI_CTRL_VDD_180, SDHCI_HOST_CONTROL2);
 }
 
 static void spacemit_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)

-- 
2.55.0


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[PATCH 3/7] mmc: sdhci-of-k1: configure PHY mode

[Yixun Lan]

From: Long Wan <long.wan@linux.spacemit.com>

Apply PHY configuration only for eMMC hosts which enable PHY function mode,
and configure drive strength and bias. While for SD/SDIO hosts mode, bypass
the PHY mode and select TX internal clock instead.

Fixes: f87b273e4b6d ("mmc: sdhci-of-k1: enable essential clock infrastructure for SD operation")
Signed-off-by: Long Wan <long.wan@linux.spacemit.com>
Signed-off-by: Yixun Lan <dlan@kernel.org>
---
 drivers/mmc/host/sdhci-of-k1.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index afd9536f2368..5dccdd4b217d 100644
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -169,21 +169,23 @@ static void spacemit_sdhci_reset(struct sdhci_host *host, u8 mask)
 	if (mask != SDHCI_RESET_ALL)
 		return;
 
-	spacemit_sdhci_setbits(host, SDHC_PHY_FUNC_EN | SDHC_PHY_PLL_LOCK,
-			       SPACEMIT_SDHC_PHY_CTRL_REG);
-
-	spacemit_sdhci_clrsetbits(host, SDHC_PHY_DRIVE_SEL,
-				  SDHC_RX_BIAS_CTRL | FIELD_PREP(SDHC_PHY_DRIVE_SEL, 4),
-				  SPACEMIT_SDHC_PHY_PADCFG_REG);
-
-	if (!(host->mmc->caps2 & MMC_CAP2_NO_MMC))
-		spacemit_sdhci_setbits(host, SDHC_MMC_CARD_MODE, SPACEMIT_SDHC_MMC_CTRL_REG);
-
-	spacemit_sdhci_setbits(host, SDHC_GEN_PAD_CLK_ON, SPACEMIT_SDHC_LEGACY_CTRL_REG);
+	if (host->mmc->caps2 & MMC_CAP2_NO_MMC) {
+		/* SD/SDIO: bypass PHY, use TX internal clock */
+		spacemit_sdhci_setbits(host, SDHC_TX_INT_CLK_SEL, SPACEMIT_SDHC_TX_CFG_REG);
 
-	if (host->mmc->caps2 & MMC_CAP2_NO_MMC)
 		spacemit_sdhci_setbits(host, SDHC_OVRRD_CLK_OEN | SDHC_FORCE_CLK_ON,
 				       SPACEMIT_SDHC_OP_EXT_REG);
+	} else {
+		/* eMMC: use PHY function mode */
+		spacemit_sdhci_setbits(host, SDHC_PHY_FUNC_EN | SDHC_PHY_PLL_LOCK,
+				       SPACEMIT_SDHC_PHY_CTRL_REG);
+
+		spacemit_sdhci_clrsetbits(host, SDHC_PHY_DRIVE_SEL,
+					  SDHC_RX_BIAS_CTRL | FIELD_PREP(SDHC_PHY_DRIVE_SEL, 4),
+					  SPACEMIT_SDHC_PHY_PADCFG_REG);
+
+		spacemit_sdhci_setbits(host, SDHC_MMC_CARD_MODE, SPACEMIT_SDHC_MMC_CTRL_REG);
+	}
 }
 
 static void spacemit_sdhci_set_uhs_signaling(struct sdhci_host *host, unsigned int timing)

-- 
2.55.0


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[PATCH 4/7] mmc: sdhci-of-k1: Improve power control

[Yixun Lan]

From: Long Wan <long.wan@linux.spacemit.com>

The default sdhci_set_power() skips the SD bus voltage select field
entirely when a vmmc regulator is present, leaving SD Bus Power in off
state of the power control register. To fix this, configure the bus
voltage explicitly.

Fixes: e5502d15b0f3 ("mmc: sdhci-of-k1: add support for SpacemiT K1 SoC")
Signed-off-by: Long Wan <long.wan@linux.spacemit.com>
Signed-off-by: Yixun Lan <dlan@kernel.org>
---
 drivers/mmc/host/sdhci-of-k1.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index 5dccdd4b217d..be770e8a9884 100644
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -496,6 +496,7 @@ static const struct sdhci_ops spacemit_sdhci_ops = {
 	.reset			= spacemit_sdhci_reset,
 	.set_bus_width		= sdhci_set_bus_width,
 	.set_clock		= spacemit_sdhci_set_clock,
+	.set_power		= sdhci_set_power_and_bus_voltage,
 	.set_uhs_signaling	= spacemit_sdhci_set_uhs_signaling,
 	.platform_execute_tuning = spacemit_sdhci_execute_tuning,
 };

-- 
2.55.0


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[PATCH 5/7] mmc: sdhci-of-k1: Use finest delay granularity for RX tuning

[Yixun Lan]

From: Long Wan <long.wan@linux.spacemit.com>

Initialize the RX delay line to 0 (finest step size) instead of 9.
This improves tuning precision by allowing smaller delay increments
when searching for the optimal sampling point.

Fixes: e9cb83c10071 ("mmc: sdhci-of-k1: add comprehensive SDR tuning support")
Signed-off-by: Long Wan <long.wan@linux.spacemit.com>
Signed-off-by: Yixun Lan <dlan@kernel.org>
---
 drivers/mmc/host/sdhci-of-k1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index be770e8a9884..257c954ce587 100644
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -84,7 +84,7 @@
 #define  SDHC_RX_DLINE_GAIN             BIT(8)
 #define  SDHC_TX_DLINE_REG_MASK         GENMASK(23, 16)
 
-#define SPACEMIT_RX_DLINE_REG		9
+#define SPACEMIT_RX_DLINE_REG		0
 #define SPACEMIT_RX_TUNE_DELAY_MIN	0x0
 #define SPACEMIT_RX_TUNE_DELAY_MAX	0xFF
 

-- 
2.55.0


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[PATCH 6/7] mmc: sdhci-of-k1: Improve RX tuning window

[Yixun Lan]

From: Long Wan <long.wan@linux.spacemit.com>

Raise the minimum delay codes of RX tuning window from 3 to 50, to more
accurately retrieve a valid configuration.

A window of 3 codes wide leaves no sampling margin, which will result
tuning tests reporting success on a configuration that drifts out of the
window under thermal or power variation.

Fixes: e9cb83c10071 ("mmc: sdhci-of-k1: add comprehensive SDR tuning support")
Signed-off-by: Long Wan <long.wan@linux.spacemit.com>
Signed-off-by: Yixun Lan <dlan@kernel.org>
---
 drivers/mmc/host/sdhci-of-k1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index 257c954ce587..a07e7db0853e 100644
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -314,7 +314,7 @@ static int spacemit_sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
 		max_pass_start = current_start;
 	}
 
-	if (max_pass_len < 3) {
+	if (max_pass_len < 50) {
 		dev_err(mmc_dev(host->mmc), "Tuning failed: no stable window found\n");
 		return -EIO;
 	}

-- 
2.55.0


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Re: [PATCH 6/7] mmc: sdhci-of-k1: Improve RX tuning window

[Hung-Chun Tseng]

On Wed, Sep 02, 2026 at 08:04:27AM +0000, Yixun Lan wrote:
> Raise the minimum delay codes of RX tuning window from 3 to 50, to more
> accurately retrieve a valid configuration.
>
> A window of 3 codes wide leaves no sampling margin, which will result
> tuning tests reporting success on a configuration that drifts out of the
> window under thermal or power variation.

I agree with the motivation, and I have some data from a K1 board that
supports it. But I would like to ask about making 50 a compile-time
constant.

Caveat up front: my board runs the vendor sdhci-spacemit driver
(6.6.63, compatible "spacemit,k1-x-sdhci"), not sdhci-of-k1.c, so the
numbers below are observations from that driver rather than a test of
this series. I could not test the series itself: rootfs on this board
is on the SD card driven by this controller, and there is no eMMC, so
a tuning regression means it does not boot.

Measured RX tuning windows, Milk-V Jupiter (K1), SDR104 SD card,
across three boots (the vendor driver already logs these):

  mmc0 (SD, rootfs):
    boot 0:  [0,55) [77,255)         -> widest 178
    boot -1: [0,54) [77,255)         -> widest 178
    boot -2: [0,50) [71,76) [79,255) -> widest 176

  mmc1 (SDIO):
    boot 0:  [0,73) [81,106) [137,255) -> widest 118
    boot -1: [0,74) [81,106) [107,108) -> widest 74
    boot -2: [0,76) [82,100)           -> widest 76

So a threshold of 50 is comfortable here. It also supports your
rationale directly: boot -2 produced a 5-code window and boot -1
produced a 1-code window on mmc1, so the narrow-window case this
patch guards against does occur in practice.

Relevant to the delay-line question in 5/7: this board's DT already
sets spacemit,rx_dline_reg = 0, so the windows above are already at
the finest step size, i.e. they should be comparable to post-5/7
behaviour rather than to the current mainline default of 9.

My question is about the form rather than the value. The vendor
driver takes this same limit from DT, per host:

  sdh@d4280000: spacemit,rx_tuning_limit = <0x32>;  /* 50 */
  sdh@d4280800: spacemit,rx_tuning_limit = <0x32>;  /* 50 */

So 50 matches what SpacemiT already ships -- but there it is a
per-controller DT property, and this patch turns it into a global
compile-time constant. Was that deliberate? The vendor design implies
the value is expected to need per-board adjustment, and with a Fixes:
tag this will land in stable, where a board with a narrower window
would go from "adjust the DT" to "patch and rebuild the kernel".

Two options, if you think the concern is real: keep it as a DT
property (matching the existing binding), or keep the constant as a
default that DT can override.

One more thing on 5/7 and 6/7: since patch 5 changes the delay-line
step from 9 to 0, the same physical timing window spans a different
number of delay codes with and without it. If 50 is calibrated against
the finest step, then backporting 6/7 without 5/7 could reject
configurations that currently work. Both carry Fixes: tags pointing at
e9cb83c10071, so they may well be picked up separately -- might be
worth making the dependency explicit for the stable maintainers.

Thanks,
Hung-Chun Tseng <alan.tseng.cs@gmail.com>

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[PATCH 7/7] mmc: sdhci-of-k1: Implement SD clock gating for voltage switch

[Yixun Lan]

From: Long Wan <long.wan@linux.spacemit.com>

reset() permanently set OVRRD_CLK_OEN and FORCE_CLK_ON for SD/SDIO hosts
and never cleared them, so the SD clock was forced on for the lifetime of
the controller and hardware auto gating never took effect.

These bits are only needed during the CMD11 1.8V voltage switch, where
the clock has to keep running so DAT[3:0] can be sampled after the
switch. Add a set_clk_gate() helper, force the clock on from set_clock()
when CMD11 is in flight, and restore auto gating from card_busy() once
the switch completes.

card_busy() is registered for all card types since the CMD11 sequence is
an SD/SDIO path and the DAT[0] level check is generic.

Signed-off-by: Long Wan <long.wan@linux.spacemit.com>
Signed-off-by: Yixun Lan <dlan@kernel.org>
---
 drivers/mmc/host/sdhci-of-k1.c | 49 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 45 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
index a07e7db0853e..5260421d394c 100644
--- a/drivers/mmc/host/sdhci-of-k1.c
+++ b/drivers/mmc/host/sdhci-of-k1.c
@@ -12,6 +12,7 @@
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/mmc.h>
+#include <linux/mmc/sd.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
@@ -162,6 +163,16 @@ static void spacemit_sdhci_prepare_tuning(struct sdhci_host *host)
 		spacemit_sdhci_setbits(host, SDHC_HS200_USE_RFIFO, SPACEMIT_SDHC_PHY_FUNC_REG);
 }
 
+static void spacemit_sdhci_set_clk_gate(struct sdhci_host *host, unsigned int auto_gate)
+{
+	if (auto_gate)
+		spacemit_sdhci_clrbits(host, SDHC_OVRRD_CLK_OEN | SDHC_FORCE_CLK_ON,
+				       SPACEMIT_SDHC_OP_EXT_REG);
+	else
+		spacemit_sdhci_setbits(host, SDHC_OVRRD_CLK_OEN | SDHC_FORCE_CLK_ON,
+				       SPACEMIT_SDHC_OP_EXT_REG);
+}
+
 static void spacemit_sdhci_reset(struct sdhci_host *host, u8 mask)
 {
 	sdhci_reset(host, mask);
@@ -172,9 +183,6 @@ static void spacemit_sdhci_reset(struct sdhci_host *host, u8 mask)
 	if (host->mmc->caps2 & MMC_CAP2_NO_MMC) {
 		/* SD/SDIO: bypass PHY, use TX internal clock */
 		spacemit_sdhci_setbits(host, SDHC_TX_INT_CLK_SEL, SPACEMIT_SDHC_TX_CFG_REG);
-
-		spacemit_sdhci_setbits(host, SDHC_OVRRD_CLK_OEN | SDHC_FORCE_CLK_ON,
-				       SPACEMIT_SDHC_OP_EXT_REG);
 	} else {
 		/* eMMC: use PHY function mode */
 		spacemit_sdhci_setbits(host, SDHC_PHY_FUNC_EN | SDHC_PHY_PLL_LOCK,
@@ -209,6 +217,20 @@ static void spacemit_sdhci_set_clock(struct sdhci_host *host, unsigned int clock
 		spacemit_sdhci_clrbits(host, SDHC_TX_INT_CLK_SEL, SPACEMIT_SDHC_TX_CFG_REG);
 
 	sdhci_set_clock(host, clock);
+
+	if (host->mmc->caps2 & MMC_CAP2_NO_MMC) {
+		/*
+		 * During CMD11 voltage switch to 1.8V, temporarily force the
+		 * clock on to ensure DAT[3:0] can be sampled correctly after
+		 * the switch. Auto gating is restored in card_busy() once the
+		 * switch completes.
+		 */
+		if ((SDHCI_GET_CMD(sdhci_readw(host, SDHCI_COMMAND)) == SD_SWITCH_VOLTAGE) &&
+		    host->mmc->ios.signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
+			if (clock)
+				spacemit_sdhci_set_clk_gate(host, 0);
+		}
+	}
 };
 
 static void spacemit_sdhci_phy_dll_init(struct sdhci_host *host)
@@ -491,6 +513,23 @@ static inline void spacemit_sdhci_get_pins(struct device *dev,
 		sdhst->pinctrl_default, sdhst->pinctrl_uhs);
 }
 
+static int spacemit_sdhci_card_busy(struct mmc_host *mmc)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	u32 present_state;
+
+	present_state = sdhci_readl(host, SDHCI_PRESENT_STATE);
+
+	if (host->mmc->caps2 & MMC_CAP2_NO_MMC) {
+		if ((SDHCI_GET_CMD(sdhci_readw(host, SDHCI_COMMAND)) == SD_SWITCH_VOLTAGE) &&
+		    host->mmc->ios.signal_voltage == MMC_SIGNAL_VOLTAGE_180)
+			/* Recover auto clock after voltage switch */
+			spacemit_sdhci_set_clk_gate(host, 1);
+	}
+
+	return !(present_state & SDHCI_DATA_0_LVL_MASK);
+}
+
 static const struct sdhci_ops spacemit_sdhci_ops = {
 	.get_max_clock		= spacemit_sdhci_clk_get_max_clock,
 	.reset			= spacemit_sdhci_reset,
@@ -555,8 +594,10 @@ static int spacemit_sdhci_probe(struct platform_device *pdev)
 
 	sdhci_get_of_property(pdev);
 
+	mops = &host->mmc_host_ops;
+	mops->card_busy = spacemit_sdhci_card_busy;
+
 	if (!(host->mmc->caps2 & MMC_CAP2_NO_MMC)) {
-		mops = &host->mmc_host_ops;
 		mops->hs400_prepare_ddr	= spacemit_sdhci_pre_select_hs400;
 		mops->hs400_complete	= spacemit_sdhci_post_select_hs400;
 		mops->hs400_downgrade	= spacemit_sdhci_pre_hs400_to_hs200;

-- 
2.55.0


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Re: [PATCH 0/7] mmc: spacemit: improve clock and tuning logic

[Adrian Hunter]

On 02/09/2026 11:04, Yixun Lan wrote:
> This series includes some bug fixes and improvement to
> SpacemiT SDHCI driver, which relate to pinctrl, PHY,
> clock, tuning logic. Most of them are quite independent,
> but put them together here for people to easy review.

Please cc the authors and testers of the fixed commits.
Also have a look at Sashiko comments:

	https://sashiko.dev/#/patchset/20260902-07-k3-sdhci-fix-v1-0-b15c5d0f64fd%40kernel.org

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