linux-kernel - [PATCH] mmc: mtk-sd: optimize register settings for hs400(es) mode

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Message-ID: <20250123074442.1617-1-andy-ld.lu@mediatek.com>
Date: Thu, 23 Jan 2025 15:44:32 +0800
From: Andy-ld Lu <andy-ld.lu@...iatek.com>
To: <ulf.hansson@...aro.org>, <matthias.bgg@...il.com>,
	<angelogioacchino.delregno@...labora.com>, <wenbin.mei@...iatek.com>
CC: <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-mediatek@...ts.infradead.org>,
	Andy-ld Lu <andy-ld.lu@...iatek.com>
Subject: [PATCH] mmc: mtk-sd: optimize register settings for hs400(es) mode

For hs400(es) mode, the 'hs400-ds-delay' is typically configured in the
dts. However, some projects may only define 'mediatek,hs400-ds-dly3',
which can lead to initialization failures in hs400es mode. CMD13 reported
response crc error in the mmc_switch_status() just after switching to
hs400es mode.

[    1.914038][   T82] mmc0: mmc_select_hs400es failed, error -84
[    1.914954][   T82] mmc0: error -84 whilst initialising MMC card

Currently, the hs400_ds_dly3 value is set within the tuning function. This
means that the PAD_DS_DLY3 field is not configured before tuning process,
which is the reason for the above-mentioned CMD13 response crc error.

Move the PAD_DS_DLY3 field configuration into msdc_prepare_hs400_tuning(),
and add a value check of hs400_ds_delay to prevent overwriting by zero when
the 'hs400-ds-delay' is not set in the dts. In addition, since hs400(es)
only tune the PAD_DS_DLY1, the PAD_DS_DLY2_SEL bit should be cleared to
bypass it.

Signed-off-by: Andy-ld Lu <andy-ld.lu@...iatek.com>
---
 drivers/mmc/host/mtk-sd.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 4b6e91372526..4e3e31ddf84b 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -273,6 +273,7 @@
 #define MSDC_PAD_TUNE_CMD2_SEL	  BIT(21)   /* RW */
 
 #define PAD_DS_TUNE_DLY_SEL       BIT(0)	  /* RW */
+#define PAD_DS_TUNE_DLY2_SEL      BIT(1)	  /* RW */
 #define PAD_DS_TUNE_DLY1	  GENMASK(6, 2)   /* RW */
 #define PAD_DS_TUNE_DLY2	  GENMASK(11, 7)  /* RW */
 #define PAD_DS_TUNE_DLY3	  GENMASK(16, 12) /* RW */
@@ -317,9 +318,10 @@
 #define PAD_CMD_TX_DLY          GENMASK(16, 12)	/* RW */
 
 /* EMMC50_PAD_DS_TUNE mask */
-#define PAD_DS_DLY_SEL		BIT(16)	/* RW */
-#define PAD_DS_DLY1		GENMASK(14, 10)	/* RW */
-#define PAD_DS_DLY3		GENMASK(4, 0)	/* RW */
+#define PAD_DS_DLY_SEL          BIT(16) /* RW */
+#define PAD_DS_DLY2_SEL         BIT(15) /* RW */
+#define PAD_DS_DLY1             GENMASK(14, 10) /* RW */
+#define PAD_DS_DLY3             GENMASK(4, 0)   /* RW */
 
 /* LOOP_TEST_CONTROL mask */
 #define TEST_LOOP_DSCLK_MUX_SEL        BIT(0)	/* RW */
@@ -2504,13 +2506,23 @@ static int msdc_execute_tuning(struct mmc_host *mmc, u32 opcode)
 static int msdc_prepare_hs400_tuning(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	struct msdc_host *host = mmc_priv(mmc);
+
 	host->hs400_mode = true;
 
-	if (host->top_base)
-		writel(host->hs400_ds_delay,
-		       host->top_base + EMMC50_PAD_DS_TUNE);
-	else
-		writel(host->hs400_ds_delay, host->base + PAD_DS_TUNE);
+	if (host->top_base) {
+		if (host->hs400_ds_dly3)
+			sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
+				      PAD_DS_DLY3, host->hs400_ds_dly3);
+		if (host->hs400_ds_delay)
+			writel(host->hs400_ds_delay,
+			       host->top_base + EMMC50_PAD_DS_TUNE);
+	} else {
+		if (host->hs400_ds_dly3)
+			sdr_set_field(host->base + PAD_DS_TUNE,
+				      PAD_DS_TUNE_DLY3, host->hs400_ds_dly3);
+		if (host->hs400_ds_delay)
+			writel(host->hs400_ds_delay, host->base + PAD_DS_TUNE);
+	}
 	/* hs400 mode must set it to 0 */
 	sdr_clr_bits(host->base + MSDC_PATCH_BIT2, MSDC_PATCH_BIT2_CFGCRCSTS);
 	/* to improve read performance, set outstanding to 2 */
@@ -2530,14 +2542,11 @@ static int msdc_execute_hs400_tuning(struct mmc_host *mmc, struct mmc_card *card
 	if (host->top_base) {
 		sdr_set_bits(host->top_base + EMMC50_PAD_DS_TUNE,
 			     PAD_DS_DLY_SEL);
-		if (host->hs400_ds_dly3)
-			sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
-				      PAD_DS_DLY3, host->hs400_ds_dly3);
+		sdr_clr_bits(host->top_base + EMMC50_PAD_DS_TUNE,
+			     PAD_DS_DLY2_SEL);
 	} else {
 		sdr_set_bits(host->base + PAD_DS_TUNE, PAD_DS_TUNE_DLY_SEL);
-		if (host->hs400_ds_dly3)
-			sdr_set_field(host->base + PAD_DS_TUNE,
-				      PAD_DS_TUNE_DLY3, host->hs400_ds_dly3);
+		sdr_clr_bits(host->base + PAD_DS_TUNE, PAD_DS_TUNE_DLY2_SEL);
 	}
 
 	host->hs400_tuning = true;
-- 
2.46.0