[PATCH v6 1/2] mtd: spi-nor: Delay the initialization of bank_size

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <tudor.ambarus@linaro.org>,
	Pratyush Yadav <pratyush@kernel.org>,
	Michael Walle <michael@walle.cc>, <linux-mtd@lists.infradead.org>
Cc: Julien Su <juliensu@mxic.com.tw>,
	Jaime Liao <jaimeliao@mxic.com.tw>,
	Jaime Liao <jaimeliao.tw@gmail.com>,
	Alvin Zhou <alvinzhou@mxic.com.tw>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>
Subject: [PATCH v6 1/2] mtd: spi-nor: Delay the initialization of bank_size
Date: Fri, 31 Mar 2023 21:46:19 +0200	[thread overview]
Message-ID: <20230331194620.839899-1-miquel.raynal@bootlin.com> (raw)

Bank size is derived from the chip's size, which in
spi_nor_init_default_params() can still be zero if the size is not
hardcoded in a table (eg. sfdp parsing). We need to delay the
initialization of this field in the "late" helpers.

Based on the fact that RWW compatible devices will use the bank_size to
derive in which bank an access is made, we absolutely want to avoid
divisions by 0. Right now there is no such opportunity between
spi_nor_init_default_params() and spi_nor_late_init_params() but it is
probably safer to enforce a default value (assuming 1 bank) as early as
possible, just in case some day code using this variable is moved
earlier than expected.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
I made the choice to keep a default value, to be honest this is not
actually needed today, so feel free to drop the line if you don't like
it, both choices seem reasonable to me.
---
 drivers/mtd/spi-nor/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 9e6a0730cdb8..f436395ca489 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2882,6 +2882,8 @@ static void spi_nor_late_init_params(struct spi_nor *nor)
 	 */
 	if (nor->flags & SNOR_F_HAS_LOCK && !nor->params->locking_ops)
 		spi_nor_init_default_locking_ops(nor);
+
+	nor->params->bank_size = div64_u64(nor->params->size, nor->info->n_banks);
 }
 
 /**
@@ -2948,7 +2950,7 @@ static void spi_nor_init_default_params(struct spi_nor *nor)
 	/* Set SPI NOR sizes. */
 	params->writesize = 1;
 	params->size = (u64)info->sector_size * info->n_sectors;
-	params->bank_size = div64_u64(params->size, info->n_banks);
+	params->bank_size = params->size;
 	params->page_size = info->page_size;
 
 	if (!(info->flags & SPI_NOR_NO_FR)) {
-- 
2.34.1


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