[U-Boot] [PATCH 01/18] Revert "sf: Fix quad bit set for micron devices"

[Cyrille Pitchen]

This reverts commit c56ae7519f141523ba1248b22b5b5169b21772fe.

Once the 'Quad Enable' bit is cleared in their Enhanced Volatile
Configuration Register (EVCR), Micron memories expect ALL commands to use
the SPI 4-4-4 protocol. Commands using SPI 1-y-z protocols are no longer
accepted.

Within the reverted commit, the write_evcr() function is implemented using
the spi_flash_write_common(), which is a shortcut for the
[ spi_flash_cmd_write_enable(), spi_flash_cmd_write(),
spi_flash_cmd_wait_ready() ] sequence.

Since the internal state of the Micron memory has been changed when the
spi_flash_cmd_write() function completes, the later call of the
spi_flash_cmd_wait_ready() function fails.

Indeed the SPI controller driver is not aware of the SPI protocol switch.

Further patches will fix the support of Micron QSPI memories.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen at atmel.com>
---
 drivers/mtd/spi/sf_internal.h |  3 ---
 drivers/mtd/spi/spi_flash.c   | 62 ++-----------------------------------------
 2 files changed, 2 insertions(+), 63 deletions(-)

diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index 007a5a085caf..7418c76b272c 100644
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -77,7 +77,6 @@ enum spi_nor_option_flags {
 #define CMD_WRITE_DISABLE		0x04
 #define CMD_WRITE_ENABLE		0x06
 #define CMD_QUAD_PAGE_PROGRAM		0x32
-#define CMD_WRITE_EVCR			0x61
 
 /* Read commands */
 #define CMD_READ_ARRAY_SLOW		0x03
@@ -91,7 +90,6 @@ enum spi_nor_option_flags {
 #define CMD_READ_STATUS1		0x35
 #define CMD_READ_CONFIG			0x35
 #define CMD_FLAG_STATUS			0x70
-#define CMD_READ_EVCR			0x65
 
 /* Bank addr access commands */
 #ifdef CONFIG_SPI_FLASH_BAR
@@ -106,7 +104,6 @@ enum spi_nor_option_flags {
 #define STATUS_QEB_WINSPAN		BIT(1)
 #define STATUS_QEB_MXIC			BIT(6)
 #define STATUS_PEC			BIT(7)
-#define STATUS_QEB_MICRON		BIT(7)
 #define SR_BP0				BIT(2)  /* Block protect 0 */
 #define SR_BP1				BIT(3)  /* Block protect 1 */
 #define SR_BP2				BIT(4)  /* Block protect 2 */
diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index 44d9e9ba0105..e52728da9a09 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -112,37 +112,6 @@ static int write_cr(struct spi_flash *flash, u8 wc)
 }
 #endif
 
-#ifdef CONFIG_SPI_FLASH_STMICRO
-static int read_evcr(struct spi_flash *flash, u8 *evcr)
-{
-	int ret;
-	const u8 cmd = CMD_READ_EVCR;
-
-	ret = spi_flash_read_common(flash, &cmd, 1, evcr, 1);
-	if (ret < 0) {
-		debug("SF: error reading EVCR\n");
-		return ret;
-	}
-
-	return 0;
-}
-
-static int write_evcr(struct spi_flash *flash, u8 evcr)
-{
-	u8 cmd;
-	int ret;
-
-	cmd = CMD_WRITE_EVCR;
-	ret = spi_flash_write_common(flash, &cmd, 1, &evcr, 1);
-	if (ret < 0) {
-		debug("SF: error while writing EVCR register\n");
-		return ret;
-	}
-
-	return 0;
-}
-#endif
-
 #ifdef CONFIG_SPI_FLASH_BAR
 static int spi_flash_write_bar(struct spi_flash *flash, u32 offset)
 {
@@ -895,34 +864,6 @@ static int spansion_quad_enable(struct spi_flash *flash)
 }
 #endif
 
-#ifdef CONFIG_SPI_FLASH_STMICRO
-static int micron_quad_enable(struct spi_flash *flash)
-{
-	u8 qeb_status;
-	int ret;
-
-	ret = read_evcr(flash, &qeb_status);
-	if (ret < 0)
-		return ret;
-
-	if (!(qeb_status & STATUS_QEB_MICRON))
-		return 0;
-
-	ret = write_evcr(flash, qeb_status & ~STATUS_QEB_MICRON);
-	if (ret < 0)
-		return ret;
-
-	/* read EVCR and check it */
-	ret = read_evcr(flash, &qeb_status);
-	if (!(ret >= 0 && !(qeb_status & STATUS_QEB_MICRON))) {
-		printf("SF: Micron EVCR Quad bit not clear\n");
-		return -EINVAL;
-	}
-
-	return ret;
-}
-#endif
-
 static int set_quad_mode(struct spi_flash *flash, u8 idcode0)
 {
 	switch (idcode0) {
@@ -937,7 +878,8 @@ static int set_quad_mode(struct spi_flash *flash, u8 idcode0)
 #endif
 #ifdef CONFIG_SPI_FLASH_STMICRO
 	case SPI_FLASH_CFI_MFR_STMICRO:
-		return micron_quad_enable(flash);
+		debug("SF: QEB is volatile for %02x flash\n", idcode0);
+		return 0;
 #endif
 	default:
 		printf("SF: Need set QEB func for %02x flash\n", idcode0);
-- 
1.8.2.2