FAILED: patch "[PATCH] mmc: sdhci-of-dwcmshc: Disable clock before DLL configuration" failed to apply to 5.15-stable tree

PATCH New [email protected] 2 participants 2 messages May 3 – May 5

Subsystems (3)

Stable branch MMC, SD and SDIO Secure digital host controller interface (SDHCI) driver

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lore

[email protected]

author maintainer

2026-05-03 11:44 UTC #0 lore raw

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 6546a49bbe656981d99a389195560999058c89c4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026050301-robe-placate-cf0b@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6546a49bbe656981d99a389195560999058c89c4 Mon Sep 17 00:00:00 2001
From: Shawn Lin <[email protected]>
Date: Wed, 8 Apr 2026 15:18:49 +0800
Subject: [PATCH] mmc: sdhci-of-dwcmshc: Disable clock before DLL configuration

According to the ASIC design recommendations, the clock must be disabled before operating the DLL to prevent glitches that could affect the internal digital logic. In extreme cases, failing to do so may cause the controller to malfunction completely.

Adds a step to disable the clock before DLL configuration and re-enables it at the end.

Fixes 08f3dff799d4 ("mmc: sdhci-of-dwcmshc: add rockchip platform support")

Cc [email protected]

Signed-off-by Shawn Lin <[email protected]>

Acked-by Adrian Hunter <[email protected]>

Signed-off-by Ulf Hansson <[email protected]>

drivers/mmc/host/sdhci-of-dwcmshc.c +16 -3

index 6139516c6488..0b2158a7e409 100644
@@ -783,12 +783,15 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 	extra |= BIT(4);
 	sdhci_writel(host, extra, reg);
 
+	/* Disable clock while config DLL */
+	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+
 	if (clock <= 52000000) {
 		if (host->mmc->ios.timing == MMC_TIMING_MMC_HS200 ||
 		    host->mmc->ios.timing == MMC_TIMING_MMC_HS400) {
 			dev_err(mmc_dev(host->mmc),
 				"Can't reduce the clock below 52MHz in HS200/HS400 mode");
-			return;
+			goto enable_clk;
 		}
 
 		/*

@@ -808,7 +811,7 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 			DLL_STRBIN_DELAY_NUM_SEL |
 			DLL_STRBIN_DELAY_NUM_DEFAULT << DLL_STRBIN_DELAY_NUM_OFFSET;
 		sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_STRBIN);
-		return;
+		goto enable_clk;
 	}
 
 	/* Reset DLL */

@@ -835,7 +838,7 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 				 500 * USEC_PER_MSEC);
 	if (err) {
 		dev_err(mmc_dev(host->mmc), "DLL lock timeout!\n");
-		return;
+		goto enable_clk;
 	}
 
 	extra = 0x1 << 16 | /* tune clock stop en */

@@ -868,6 +871,16 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 		DLL_STRBIN_TAPNUM_DEFAULT |
 		DLL_STRBIN_TAPNUM_FROM_SW;
 	sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_STRBIN);
+
+enable_clk:
+	/*
+	 * The sdclk frequency select bits in SDHCI_CLOCK_CONTROL are not functional
+	 * on Rockchip's SDHCI implementation. Instead, the clock frequency is fully
+	 * controlled via external clk provider by calling clk_set_rate(). Consequently,
+	 * passing 0 to sdhci_enable_clk() only re-enables the already-configured clock,
+	 * which matches the hardware's actual behavior.
+	 */
+	sdhci_enable_clk(host, 0);
 }
 
 static void rk35xx_sdhci_reset(struct sdhci_host *host, u8 mask)

Sasha Levin

maintainer

2026-05-05 10:18 UTC #1 lore raw

PATCH 1/1 mmc: sdhci-of-dwcmshc: Disable clock before DLL configuration

From: Shawn Lin <[email protected]>

[ Upstream commit 6546a49bbe656981d99a389195560999058c89c4 ]

Adds a step to disable the clock before DLL configuration and re-enables it at the end.

Fixes 08f3dff799d4 ("mmc: sdhci-of-dwcmshc: add rockchip platform support")

Cc [email protected]

Signed-off-by Shawn Lin <[email protected]>

Acked-by Adrian Hunter <[email protected]>

Signed-off-by Ulf Hansson <[email protected]>

[ dropped HS200/HS400 block and BIT(4) line, converted the single `return` in `if (clock <= 400000)` to `goto enable_clk` ]

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/mmc/host/sdhci-of-dwcmshc.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

drivers/mmc/host/sdhci-of-dwcmshc.c +15 -2

index eb7213a8b5ea8..088c6ffa6fb24 100644
@@ -213,10 +213,13 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 	extra &= ~BIT(0);
 	sdhci_writel(host, extra, reg);
 
+	/* Disable clock while config DLL */
+	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+
 	if (clock <= 400000) {
 		/* Disable DLL to reset sample clock */
 		sdhci_writel(host, 0, DWCMSHC_EMMC_DLL_CTRL);
-		return;
+		goto enable_clk;
 	}
 
 	/* Reset DLL */

@@ -234,7 +237,7 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 				 500 * USEC_PER_MSEC);
 	if (err) {
 		dev_err(mmc_dev(host->mmc), "DLL lock timeout!\n");
-		return;
+		goto enable_clk;
 	}
 
 	extra = 0x1 << 16 | /* tune clock stop en */

@@ -255,6 +258,16 @@ static void dwcmshc_rk3568_set_clock(struct sdhci_host *host, unsigned int clock
 		DLL_STRBIN_TAPNUM_DEFAULT |
 		DLL_STRBIN_TAPNUM_FROM_SW;
 	sdhci_writel(host, extra, DWCMSHC_EMMC_DLL_STRBIN);
+
+enable_clk:
+	/*
+	 * The sdclk frequency select bits in SDHCI_CLOCK_CONTROL are not functional
+	 * on Rockchip's SDHCI implementation. Instead, the clock frequency is fully
+	 * controlled via external clk provider by calling clk_set_rate(). Consequently,
+	 * passing 0 to sdhci_enable_clk() only re-enables the already-configured clock,
+	 * which matches the hardware's actual behavior.
+	 */
+	sdhci_enable_clk(host, 0);
 }
 
 static void rk35xx_sdhci_reset(struct sdhci_host *host, u8 mask)

Signature · 1 line

2.53.0