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Subject[PATCH v2 2/2] mmc: core: adjust polling interval for CMD1
Date
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@samsung.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
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