Messages in this thread Patch in this message | | | From | Pratyush Yadav <> | Subject | [PATCH v12 07/14] mtd: spi-nor: core: do 2 byte reads for SR and FSR in DTR mode | Date | Thu, 3 Sep 2020 22:43:06 +0530 |
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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 83ad58508855..429151dfcddf 100644 --- a/drivers/mtd/spi-nor/core.c +++ b/drivers/mtd/spi-nor/core.c @@ -364,7 +364,7 @@ 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. */ @@ -382,6 +382,11 @@ static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr) if (spi_nor_protocol_is_dtr(nor->reg_proto)) { op.addr.nbytes = nor->params->rdsr_addr_nbytes; op.dummy.nbytes = nor->params->rdsr_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); @@ -400,7 +405,8 @@ 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. */ @@ -418,6 +424,11 @@ static int spi_nor_read_fsr(struct spi_nor *nor, u8 *fsr) if (spi_nor_protocol_is_dtr(nor->reg_proto)) { op.addr.nbytes = nor->params->rdsr_addr_nbytes; op.dummy.nbytes = nor->params->rdsr_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); -- 2.25.0
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