[PATCH v6 11/19] mtd: spi-nor: core: do 2 byte reads for SR and FSR in DTR mode

Pratyush Yadav
2020-05-20T16:32:19Z

Some controllers, like the cadence qspi controller, have trouble reading
only 1 byte in DTR mode. So, do 2 byte reads for SR and FSR commands in
DTR mode, and then discard the second byte.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---
drivers/mtd/spi-nor/core.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 2ad248140b6c..5cb7e391cd29 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -350,7 +350,7 @@ int spi_nor_write_disable(struct spi_nor *nor)
* spi_nor_read_sr() - Read the Status Register.
* @nor: pointer to 'struct spi_nor'.
* @sr: pointer to a DMA-able buffer where the value of the
- * Status Register will be written.
+ * Status Register will be written. Should be at least 2 bytes.
*
* Return: 0 on success, -errno otherwise.
*/
@@ -371,6 +371,11 @@ static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
op.addr.nbytes = addr_bytes;
op.addr.val = 0;
op.dummy.nbytes = dummy;
+ /*
+ * We don't want to read only one byte in DTR mode. So,
+ * read 2 and then discard the second byte.
+ */
+ op.data.nbytes = 2;
}

spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);
@@ -394,7 +399,8 @@ static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
* spi_nor_read_fsr() - Read the Flag Status Register.
* @nor: pointer to 'struct spi_nor'
* @fsr: pointer to a DMA-able buffer where the value of the
- * Flag Status Register will be written.
+ * Flag Status Register will be written. Should be at least 2
+ * bytes.
*
* Return: 0 on success, -errno otherwise.
*/
@@ -415,6 +421,11 @@ static int spi_nor_read_fsr(struct spi_nor *nor, u8 *fsr)
op.addr.nbytes = addr_bytes;
op.addr.val = 0;
op.dummy.nbytes = dummy;
+ /*
+ * We don't want to read only one byte in DTR mode. So,
+ * read 2 and then discard the second byte.
+ */
+ op.data.nbytes = 2;
}

spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);
--
2.26.2