[PATCH] mtd: spi-nor: handle unsupported FSR opcodes properly

[Oleksandr Ocheretnyi <oocheret@xxxxxxxxx>]

Commit 094d3b9 ("mtd: spi-nor: Add USE_FSR flag for n25q* entries")
and following one 8f93826 ("mtd: spi-nor: micron-st: convert USE_FSR
to a manufacturer flag") enables SPINOR_OP_RDFSR opcode handling ability,
however some controller drivers still cannot handle it properly in
the micron_st_nor_ready() call what breaks some mtd callbacks with
next error logs:

mtdblock: erase of region [address1, size1] on "BIOS" failed
mtdblock: erase of region [address2, size2] on "BIOS" failed

Just skip subsequent processing of the SPINOR_OP_RDFSR opcode's results
because of -ENOTSUPP return value of the micron_st_nor_read_fsr()
if there is no proper handling of that opcode as it's been before
commit 094d3b9 ("mtd: spi-nor: Add USE_FSR flag for n25q* entries")

Signed-off-by: Oleksandr Ocheretnyi <oocheret@xxxxxxxxx>
---
 drivers/mtd/spi-nor/micron-st.c | 6 +++++-
 drivers/spi/spi-intel.c         | 3 ++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/micron-st.c b/drivers/mtd/spi-nor/micron-st.c
index a96f74e0f568..507e675d81e0 100644
--- a/drivers/mtd/spi-nor/micron-st.c
+++ b/drivers/mtd/spi-nor/micron-st.c
@@ -399,8 +399,12 @@ static int micron_st_nor_ready(struct spi_nor *nor)
 		return sr_ready;
 
 	ret = micron_st_nor_read_fsr(nor, nor->bouncebuf);
-	if (ret)
+	if (ret < 0) {
+		/* Check if read FSR is supported. If not, skip it. */
+		if (ret == -ENOTSUPP)
+			return sr_ready;
 		return ret;
+	}
 
 	if (nor->bouncebuf[0] & (FSR_E_ERR | FSR_P_ERR)) {
 		if (nor->bouncebuf[0] & FSR_E_ERR)
diff --git a/drivers/spi/spi-intel.c b/drivers/spi/spi-intel.c
index 50f42983b950..f0313a718d1b 100644
--- a/drivers/spi/spi-intel.c
+++ b/drivers/spi/spi-intel.c
@@ -352,7 +352,8 @@ static int intel_spi_hw_cycle(struct intel_spi *ispi, u8 opcode, size_t len)
 		val |= HSFSTS_CTL_FCYCLE_RDSR;
 		break;
 	default:
-		return -EINVAL;
+		dev_dbg(ispi->dev, "%#x not supported\n", opcode);
+		return -ENOTSUPP;
 	}
 
 	if (len > INTEL_SPI_FIFO_SZ)
-- 
2.28.0