mtd: nand: wait for tWHR after NAND_CMD_STATUS / NAND_CMD_READID

Message ID 1506397164-3648-1-git-send-email-yamada.masahiro@socionext.com
State New
Headers show
Series
  • mtd: nand: wait for tWHR after NAND_CMD_STATUS / NAND_CMD_READID
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Commit Message

Masahiro Yamada Sept. 26, 2017, 3:39 a.m.
Read Status and Read ID require tWHR before reading the first data.
Insert a very short wait to make sure to meet the spec.

I have not seen any problem report for now, but nand_command() and
nand_command_lP() are generic hooks, so it makes sense to implement
fail-safe code here.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

---

 drivers/mtd/nand/nand_base.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

-- 
2.7.4


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Patch

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index b1cf32c..55c0ba5 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -742,9 +742,12 @@  static void nand_command(struct mtd_info *mtd, unsigned int command,
 	case NAND_CMD_ERASE1:
 	case NAND_CMD_ERASE2:
 	case NAND_CMD_SEQIN:
+	case NAND_CMD_SET_FEATURES:
+		return;
+
 	case NAND_CMD_STATUS:
 	case NAND_CMD_READID:
-	case NAND_CMD_SET_FEATURES:
+		ndelay(200);	/* tWHR */
 		return;
 
 	case NAND_CMD_RESET:
@@ -871,9 +874,12 @@  static void nand_command_lp(struct mtd_info *mtd, unsigned int command,
 	case NAND_CMD_ERASE1:
 	case NAND_CMD_ERASE2:
 	case NAND_CMD_SEQIN:
+	case NAND_CMD_SET_FEATURES:
+		return;
+
 	case NAND_CMD_STATUS:
 	case NAND_CMD_READID:
-	case NAND_CMD_SET_FEATURES:
+		ndelay(200);	/* tWHR */
 		return;
 
 	case NAND_CMD_RNDIN: