linux-kernel - [PATCH] mmc: make ext_csd dump more human-readable

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Date:   Fri, 31 Jan 2020 12:20:08 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     linux-mmc@...r.kernel.org, Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Avri Altman <avri.altman@....com>,
        Chaotian Jing <chaotian.jing@...iatek.com>,
        Ming Lei <ming.lei@...hat.com>,
        YueHaibing <yuehaibing@...wei.com>,
        Zachary Hays <zhays@...mark.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] mmc: make ext_csd dump more human-readable

The current ext_csd in the debugfs shows 1024 chars in one line,
which is unreadable at least for humans (but perhaps it could be
handier if somebody is processing it by a tool).

This commit makes the output format more human-readable; shows 8 byte
in each line, with address in the left-most column:

  0: 00 00 00 00 00 00 00 00
  8: 00 00 00 00 00 00 00 00
 16: 01 01 00 c0 6a 02 00 00
 24: 00 00 00 00 00 00 00 00
 32: 00 01 01 00 00 00 00 00
     <snip>
496: 05 00 03 01 20 3c 01 01
504: 01 00 00 00 00 00 00 00

Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
---

 drivers/mmc/core/block.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 663d87924e5e..79044b3cbd84 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2728,8 +2728,8 @@ static int mmc_dbg_card_status_get(void *data, u64 *val)
 DEFINE_DEBUGFS_ATTRIBUTE(mmc_dbg_card_status_fops, mmc_dbg_card_status_get,
 			 NULL, "%08llx\n");
 
-/* That is two digits * 512 + 1 for newline */
-#define EXT_CSD_STR_LEN 1025
+/* 3 chars (2 digits + space) for each byte, 5 additional chars for each line */
+#define EXT_CSD_STR_LEN		(512 * 3 + 512 / 8 * 5)
 
 static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
 {
@@ -2740,7 +2740,7 @@ static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
 	char *buf;
 	ssize_t n = 0;
 	u8 *ext_csd;
-	int err, i;
+	int err, i, j;
 
 	buf = kmalloc(EXT_CSD_STR_LEN + 1, GFP_KERNEL);
 	if (!buf)
@@ -2762,9 +2762,12 @@ static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
 		goto out_free;
 	}
 
-	for (i = 0; i < 512; i++)
-		n += sprintf(buf + n, "%02x", ext_csd[i]);
-	n += sprintf(buf + n, "\n");
+	for (i = 0; i < 512; i += 8) {
+		n += sprintf(buf + n, "%3d:", i);
+		for (j = i; j < i + 8; j++)
+			n += sprintf(buf + n, " %02x", ext_csd[j]);
+		n += sprintf(buf + n, "\n");
+	}
 
 	if (n != EXT_CSD_STR_LEN) {
 		err = -EINVAL;
-- 
2.17.1