linux-kernel - [PATCH v2 2/2] mmc: core: adjust polling interval for CMD1

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Message-Id: <20211104063231.2115-3-huijin.park@samsung.com>
Date:   Thu,  4 Nov 2021 15:32:31 +0900
From:   Huijin Park <huijin.park@...sung.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Huijin Park <bbanghj.park@...il.com>,
        Huijin Park <huijin.park@...sung.com>
Subject: [PATCH v2 2/2] mmc: core: adjust polling interval for CMD1

In mmc_send_op_cond(), loops are continuously performed at the same
interval of 10 ms.  However the behaviour is not good for some eMMC
which can be out from a busy state earlier than 10 ms if normal.

Rather than fixing about the interval time in mmc_send_op_cond(),
let's instead convert into using the common __mmc_poll_for_busy().

The reason for adjusting the interval time is that it is important
to reduce the eMMC initialization time, especially in devices that
use eMMC as rootfs.

Test log(eMMC:KLM8G1GETF-B041):

before: 12 ms (0.311016 - 0.298729)
[    0.295823] mmc0: starting CMD0 arg 00000000 flags 000000c0
[    0.298729] mmc0: starting CMD1 arg 40000080 flags 000000e1<-start
[    0.311016] mmc0: starting CMD1 arg 40000080 flags 000000e1<-finish
[    0.311336] mmc0: starting CMD2 arg 00000000 flags 00000007

after: 2 ms (0.301270 - 0.298762)
[    0.295862] mmc0: starting CMD0 arg 00000000 flags 000000c0
[    0.298762] mmc0: starting CMD1 arg 40000080 flags 000000e1<-start
[    0.299067] mmc0: starting CMD1 arg 40000080 flags 000000e1
[    0.299441] mmc0: starting CMD1 arg 40000080 flags 000000e1
[    0.299879] mmc0: starting CMD1 arg 40000080 flags 000000e1
[    0.300446] mmc0: starting CMD1 arg 40000080 flags 000000e1
[    0.301270] mmc0: starting CMD1 arg 40000080 flags 000000e1<-finish
[    0.301572] mmc0: starting CMD2 arg 00000000 flags 00000007

Signed-off-by: Huijin Park <huijin.park@...sung.com>

diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 9946733a34c6..d63d1c735335 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -58,6 +58,12 @@ struct mmc_busy_data {
 	enum mmc_busy_cmd busy_cmd;
 };
 
+struct mmc_op_cond_busy_data {
+	struct mmc_host *host;
+	u32 ocr;
+	struct mmc_command *cmd;
+};
+
 int __mmc_send_status(struct mmc_card *card, u32 *status, unsigned int retries)
 {
 	int err;
@@ -173,43 +179,62 @@ int mmc_go_idle(struct mmc_host *host)
 	return err;
 }
 
+static int __mmc_send_op_cond_cb(void *cb_data, bool *busy)
+{
+	struct mmc_op_cond_busy_data *data = cb_data;
+	struct mmc_host *host = data->host;
+	struct mmc_command *cmd = data->cmd;
+	u32 ocr = data->ocr;
+	int err = 0;
+
+	err = mmc_wait_for_cmd(host, cmd, 0);
+	if (err)
+		return err;
+
+	if (mmc_host_is_spi(host)) {
+		if (!(cmd->resp[0] & R1_SPI_IDLE)) {
+			*busy = false;
+			return 0;
+		}
+	} else {
+		if (cmd->resp[0] & MMC_CARD_BUSY) {
+			*busy = false;
+			return 0;
+		}
+	}
+
+	*busy = true;
+
+	/*
+	 * According to eMMC specification v5.1 section 6.4.3, we
+	 * should issue CMD1 repeatedly in the idle state until
+	 * the eMMC is ready. Otherwise some eMMC devices seem to enter
+	 * the inactive mode after mmc_init_card() issued CMD0 when
+	 * the eMMC device is busy.
+	 */
+	if (!ocr && !mmc_host_is_spi(host))
+		cmd->arg = cmd->resp[0] | BIT(30);
+
+	return 0;
+}
+
 int mmc_send_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
 {
 	struct mmc_command cmd = {};
-	int i, err = 0;
+	int err = 0;
+	struct mmc_op_cond_busy_data cb_data = {
+		.host = host,
+		.ocr = ocr,
+		.cmd = &cmd
+	};
 
 	cmd.opcode = MMC_SEND_OP_COND;
 	cmd.arg = mmc_host_is_spi(host) ? 0 : ocr;
 	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R3 | MMC_CMD_BCR;
 
-	for (i = 100; i; i--) {
-		err = mmc_wait_for_cmd(host, &cmd, 0);
-		if (err)
-			break;
-
-		/* wait until reset completes */
-		if (mmc_host_is_spi(host)) {
-			if (!(cmd.resp[0] & R1_SPI_IDLE))
-				break;
-		} else {
-			if (cmd.resp[0] & MMC_CARD_BUSY)
-				break;
-		}
-
-		err = -ETIMEDOUT;
-
-		mmc_delay(10);
-
-		/*
-		 * According to eMMC specification v5.1 section 6.4.3, we
-		 * should issue CMD1 repeatedly in the idle state until
-		 * the eMMC is ready. Otherwise some eMMC devices seem to enter
-		 * the inactive mode after mmc_init_card() issued CMD0 when
-		 * the eMMC device is busy.
-		 */
-		if (!ocr && !mmc_host_is_spi(host))
-			cmd.arg = cmd.resp[0] | BIT(30);
-	}
+	err = __mmc_poll_for_busy(host, 1000, &__mmc_send_op_cond_cb, &cb_data);
+	if (err)
+		return err;
 
 	if (rocr && !mmc_host_is_spi(host))
 		*rocr = cmd.resp[0];
-- 
2.17.1