[U-Boot] [PATCH] mtd: cfi: Fix checking status register feature

[York Sun]

Commit 72443c7f7d21 ("mtd: cfi: Add support for status register
polling") added a feature check to determine if status register
is available for certain flash chips. The "lower software bits"
register used to determine this feature is not backward compati-
ble. Older flash chips without this feature has reserved value
0xff. Instead of checking "lower software bits" register, use
CFI primary vendor-specific extended query. Since CFI version
1.4, software features can be read from offset 0x53 according to
document AN201168 from Cypress.

Signed-off-by: York Sun <york.sun at nxp.com>
CC: Marek Vasut <marek.vasut at gmail.com>
---

 drivers/mtd/cfi_flash.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/cfi_flash.c b/drivers/mtd/cfi_flash.c
index 8a5babe..f096e03 100644
--- a/drivers/mtd/cfi_flash.c
+++ b/drivers/mtd/cfi_flash.c
@@ -1694,7 +1694,7 @@ static void cmdset_amd_read_jedec_ids(flash_info_t *info)
 {
 	ushort bankId = 0;
 	uchar  manuId;
-	uchar  lsbits;
+	uchar  feature;
 
 	flash_write_cmd(info, 0, 0, AMD_CMD_RESET);
 	flash_unlock_seq(info, 0);
@@ -1710,8 +1710,14 @@ static void cmdset_amd_read_jedec_ids(flash_info_t *info)
 	}
 	info->manufacturer_id = manuId;
 
-	lsbits = flash_read_uchar(info, FLASH_OFFSET_LOWER_SW_BITS);
-	info->sr_supported = lsbits & BIT(0);
+	debug("info->ext_addr = 0x%x, cfi_version = 0x%x\n",
+	      info->ext_addr, info->cfi_version);
+	if (info->ext_addr && info->cfi_version >= 0x3134) {
+		/* read software feature (at 0x53) */
+		feature = flash_read_uchar(info, info->ext_addr + 0x13);
+		debug("feature = 0x%x\n", feature);
+		info->sr_supported = feature & 0x1;
+	}
 
 	switch (info->chipwidth){
 	case FLASH_CFI_8BIT:
-- 
2.7.4