linux-kernel - [PATCH v3] mtd: spi-nor: simplify spi_nor_get_flash

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Date: Mon,  3 Jun 2024 15:40:55 +0200
From: Michael Walle <mwalle@...nel.org>
To: Tudor Ambarus <tudor.ambarus@...aro.org>,
	Pratyush Yadav <pratyush@...nel.org>,
	Michael Walle <mwalle@...nel.org>,
	Miquel Raynal <miquel.raynal@...tlin.com>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>
Cc: linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3] mtd: spi-nor: simplify spi_nor_get_flash_info()

Rework spi_nor_get_flash_info() to make it look more straight forward
and esp. don't return early. The latter is a preparation to check for
deprecated flashes.

Signed-off-by: Michael Walle <mwalle@...nel.org>
---
v3:
 - rework the handling quite a bit, thanks Tudor.
 - drop the spurious comment about the partitions, it goes way back
   until the initial support. I don't think it's accurate anymore.
   If the flash has the same size, the partitions can be trusted. If
   not, anything can happen.. We don't know.

v2/v1:
 - none, this is a remaining patch of my spring cleanup series.

 drivers/mtd/spi-nor/core.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 7128d45870d4..e0c4efc424f4 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3298,32 +3298,28 @@ static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
 
 	if (name)
 		info = spi_nor_match_name(nor, name);
-	/* Try to auto-detect if chip name wasn't specified or not found */
-	if (!info)
-		return spi_nor_detect(nor);
-
 	/*
-	 * If caller has specified name of flash model that can normally be
-	 * detected using JEDEC, let's verify it.
+	 * Auto-detect if chip name wasn't specified or not found, or the chip
+	 * has an ID. If the chip supposedly has an ID, we also do an
+	 * auto-detection to compare it later.
 	 */
-	if (name && info->id) {
+	if (!info || info->id) {
 		const struct flash_info *jinfo;
 
 		jinfo = spi_nor_detect(nor);
-		if (IS_ERR(jinfo)) {
+		if (IS_ERR(jinfo))
 			return jinfo;
-		} else if (jinfo != info) {
-			/*
-			 * JEDEC knows better, so overwrite platform ID. We
-			 * can't trust partitions any longer, but we'll let
-			 * mtd apply them anyway, since some partitions may be
-			 * marked read-only, and we don't want to loose that
-			 * information, even if it's not 100% accurate.
-			 */
+
+		/*
+		 * If caller has specified name of flash model that can normally
+		 * be detected using JEDEC, let's verify it.
+		 */
+		if (info && jinfo != info)
 			dev_warn(nor->dev, "found %s, expected %s\n",
 				 jinfo->name, info->name);
-			info = jinfo;
-		}
+
+		/* If info was set before, JEDEC knows better. */
+		info = jinfo;
 	}
 
 	return info;
-- 
2.39.2