[PATCH 0/2] firewire: core: optimization for the quirk of Sony DVMC-DA1

[PATCH 0/2] firewire: core: optimization for the quirk of Sony DVMC-DA1

[Takashi Sakamoto]

Hi,

A quirk was reported that Sony DVMC-DA1 has a quirk in its configuration
ROM[1]. It has the legacy layout of configuration ROM[2] with the quirk
that the descriptor leaf entry locates just after the vendor directory
entry in its root directory. It is not the layout in the documentation
since the usual descriptor leaf entry locates just after the vendor
immediate entry. Current implementation of firewire-core fail to pick up
the content of descriptor leaf for vendor name. 

This series of changes is to optimize for the quirk, including a slight
correction of documentation for the relevant kernel API. The changes
are written to be accepted to the release candidates of v6.8 so that
they don't conflict to the changes in for-next branch[3], thus they
do not necessarily have a good look.

[1] https://lore.kernel.org/lkml/20240126011705.GA22564@workstation.local/
[2] Configuration ROM for AV/C Devices 1.0 (1394 Trading Association, Dec
2000, TA Document 1999027)
https://web.archive.org/web/20210216003030/http://1394ta.org/wp-content/uploads/2015/07/1999027.pdf
[3] https://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394.git/log/?h=for-next

Takashi Sakamoto (2):
  firewire: core: correct documentation of fw_csr_string() kernel API
  firewire: core: search descriptor leaf just after vendor directory
    entry in root directory

 drivers/firewire/core-device.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

-- 
2.40.1

[PATCH 1/2] firewire: core: correct documentation of fw_csr_string() kernel API

[Takashi Sakamoto]

Against its current description, the kernel API can accepts all types of
directory entries.

This commit corrects the documentation.

Cc: stable@vger.kernel.org
Fixes: 3c2c58cb33b3 ("firewire: core: fw_csr_string addendum")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 0547253d16fe..e4cb5106fb7d 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -118,10 +118,9 @@ static int textual_leaf_to_string(const u32 *block, char *buf, size_t size)
  * @buf:	where to put the string
  * @size:	size of @buf, in bytes
  *
- * The string is taken from a minimal ASCII text descriptor leaf after
- * the immediate entry with @key.  The string is zero-terminated.
- * An overlong string is silently truncated such that it and the
- * zero byte fit into @size.
+ * The string is taken from a minimal ASCII text descriptor leaf just after the entry with the
+ * @key. The string is zero-terminated. An overlong string is silently truncated such that it
+ * and the zero byte fit into @size.
  *
  * Returns strlen(buf) or a negative error code.
  */
-- 
2.40.1

[PATCH 2/2] firewire: core: search descriptor leaf just after vendor directory entry in root directory

[Takashi Sakamoto]

It appears that Sony DVMC-DA1 has a quirk that the descriptor leaf entry
locates just after the vendor directory entry in root directory. This is
not conformant to the legacy layout of configuration ROM described in
Configuration ROM for AV/C Devices 1.0 (1394 Trading Association, Dec 2000,
TA Document 1999027).

This commit changes current implementation to parse configuration ROM for
device attributes so that the descriptor leaf entry can be detected for
the vendor name.

$ config-rom-pretty-printer < Sony-DVMC-DA1.img
               ROM header and bus information block
               -----------------------------------------------------------------
1024  041ee7fb  bus_info_length 4, crc_length 30, crc 59387
1028  31333934  bus_name "1394"
1032  e0644000  irmc 1, cmc 1, isc 1, bmc 0, cyc_clk_acc 100, max_rec 4 (32)
1036  08004603  company_id 080046     |
1040  0014193c  device_id 12886219068  | EUI-64 576537731003586876

               root directory
               -----------------------------------------------------------------
1044  0006b681  directory_length 6, crc 46721
1048  03080046  vendor
1052  0c0083c0  node capabilities: per IEEE 1394
1056  8d00000a  --> eui-64 leaf at 1096
1060  d1000003  --> unit directory at 1072
1064  c3000005  --> vendor directory at 1084
1068  8100000a  --> descriptor leaf at 1108

               unit directory at 1072
               -----------------------------------------------------------------
1072  0002cdbf  directory_length 2, crc 52671
1076  1200a02d  specifier id
1080  13010000  version

               vendor directory at 1084
               -----------------------------------------------------------------
1084  00020cfe  directory_length 2, crc 3326
1088  17fa0000  model
1092  81000008  --> descriptor leaf at 1124

               eui-64 leaf at 1096
               -----------------------------------------------------------------
1096  0002c66e  leaf_length 2, crc 50798
1100  08004603  company_id 080046     |
1104  0014193c  device_id 12886219068  | EUI-64 576537731003586876

               descriptor leaf at 1108
               -----------------------------------------------------------------
1108  00039e26  leaf_length 3, crc 40486
1112  00000000  textual descriptor
1116  00000000  minimal ASCII
1120  536f6e79  "Sony"

               descriptor leaf at 1124
               -----------------------------------------------------------------
1124  0005001d  leaf_length 5, crc 29
1128  00000000  textual descriptor
1132  00000000  minimal ASCII
1136  44564d43  "DVMC"
1140  2d444131  "-DA1"
1144  00000000

Suggested-by: Adam Goldman <adamg@pobox.com>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index e4cb5106fb7d..7d3346b3a2bf 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -367,8 +367,17 @@ static ssize_t show_text_leaf(struct device *dev,
 	for (i = 0; i < ARRAY_SIZE(directories) && !!directories[i]; ++i) {
 		int result = fw_csr_string(directories[i], attr->key, buf, bufsize);
 		// Detected.
-		if (result >= 0)
+		if (result >= 0) {
 			ret = result;
+		} else if (i == 0 && attr->key == CSR_VENDOR) {
+			// Sony DVMC-DA1 has configuration ROM such that the descriptor leaf entry
+			// in the root directory follows to the directory entry for vendor ID
+			// instead of the immediate value for vendor ID.
+			result = fw_csr_string(directories[i], CSR_DIRECTORY | attr->key, buf,
+					       bufsize);
+			if (result >= 0)
+				ret = result;
+		}
 	}
 
 	if (ret >= 0) {
-- 
2.40.1