From 354b412967016e2f99fb2d5113e7b92b539f33b6 Mon Sep 17 00:00:00 2001 From: Pratyush Yadav Date: Mon, 5 Oct 2020 21:01:30 +0530 Subject: [PATCH] mtd: spi-nor: core: do 2 byte reads for SR and FSR in DTR mode 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 Signed-off-by: Vignesh Raghavendra Reviewed-by: Tudor Ambarus Link: https://lore.kernel.org/r/20201005153138.6437-8-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 d63dfd7d4b31f..518d16511dee4 100644 --- a/drivers/mtd/spi-nor/core.c +++ b/drivers/mtd/spi-nor/core.c @@ -370,7 +370,7 @@ 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. */ @@ -388,6 +388,11 @@ static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr) if (nor->reg_proto == SNOR_PROTO_8_8_8_DTR) { 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); @@ -408,7 +413,8 @@ 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. */ @@ -426,6 +432,11 @@ static int spi_nor_read_fsr(struct spi_nor *nor, u8 *fsr) if (nor->reg_proto == SNOR_PROTO_8_8_8_DTR) { 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); -- 2.30.2