From: Joshua Yeong <joshua.yeong@starfivetech.com>
To: <linux-i3c@lists.infradead.org>
Cc: Joshua Yeong <joshua.yeong@starfivetech.com>
Subject: [PATCH] i3c: Add fallback method for GETMXDS CCC
Date: Mon, 28 Aug 2023 23:20:35 +0800 [thread overview]
Message-ID: <20230828152035.15498-1-joshua.yeong@starfivetech.com> (raw)
Some I3C hardware will report error when incorrect length is received from device. GETMXDS CCC are availble in 2 formats; without turnaround time (format 1) and with turnaround time (format 2). There is no mechanics to determine which format is supported by device. In case sending GETMXDS CCC format 2 resulted failure, try sending GETMXDS CCC format 1 instead.
Signed-off-by: Joshua Yeong <joshua.yeong@starfivetech.com>
---
drivers/i3c/master.c | 33 ++++++++++++++++++++++++++++-----
include/linux/i3c/ccc.h | 17 +++++++++++++++--
2 files changed, 43 insertions(+), 7 deletions(-)
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 351c81a929a6..8e6449ca724b 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -1076,10 +1076,37 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master,
struct i3c_device_info *info)
{
struct i3c_ccc_getmxds *getmaxds;
+ struct i3c_ccc_getmxds_turnaround *getmaxds_ta;
struct i3c_ccc_cmd_dest dest;
struct i3c_ccc_cmd cmd;
int ret;
+ getmaxds_ta = i3c_ccc_cmd_dest_init(&dest, info->dyn_addr,
+ sizeof(*getmaxds_ta));
+ if (!getmaxds_ta)
+ return -ENOMEM;
+
+ i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMXDS, &dest, 1);
+ ret = i3c_master_send_ccc_cmd_locked(master, &cmd);
+ if (ret) {
+ goto alternative;
+ }
+
+ if (dest.payload.len != 2 && dest.payload.len != 5) {
+ ret = -EIO;
+ goto out;
+ }
+
+ info->max_read_ds = getmaxds_ta->maxrd;
+ info->max_write_ds = getmaxds_ta->maxwr;
+ if (dest.payload.len == 5)
+ info->max_read_turnaround = getmaxds_ta->maxrdturn[0] |
+ ((u32)getmaxds_ta->maxrdturn[1] << 8) |
+ ((u32)getmaxds_ta->maxrdturn[2] << 16);
+
+alternative:
+ i3c_ccc_cmd_dest_cleanup(&dest);
+
getmaxds = i3c_ccc_cmd_dest_init(&dest, info->dyn_addr,
sizeof(*getmaxds));
if (!getmaxds)
@@ -1090,17 +1117,13 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master,
if (ret)
goto out;
- if (dest.payload.len != 2 && dest.payload.len != 5) {
+ if (dest.payload.len != 2) {
ret = -EIO;
goto out;
}
info->max_read_ds = getmaxds->maxrd;
info->max_write_ds = getmaxds->maxwr;
- if (dest.payload.len == 5)
- info->max_read_turnaround = getmaxds->maxrdturn[0] |
- ((u32)getmaxds->maxrdturn[1] << 8) |
- ((u32)getmaxds->maxrdturn[2] << 16);
out:
i3c_ccc_cmd_dest_cleanup(&dest);
diff --git a/include/linux/i3c/ccc.h b/include/linux/i3c/ccc.h
index ad59a4ae60d1..50ed41d4d5a1 100644
--- a/include/linux/i3c/ccc.h
+++ b/include/linux/i3c/ccc.h
@@ -269,14 +269,27 @@ enum i3c_tsco {
#define I3C_CCC_MAX_SDR_FSCL(x) ((x) & I3C_CCC_MAX_SDR_FSCL_MASK)
/**
- * struct i3c_ccc_getmxds - payload passed to GETMXDS CCC
+ * struct i3c_ccc_getmxds - payload passed to GETMXDS CCC without turnaround
+ * (format 1)
+ *
+ * @maxwr: write limitations
+ * @maxrd: read limitations
+ */
+struct i3c_ccc_getmxds {
+ u8 maxwr;
+ u8 maxrd;
+} __packed;
+
+/**
+ * struct i3c_ccc_getmxds_ta - payload passed to GETMXDS CCC with turnaround
+ * (format 2)
*
* @maxwr: write limitations
* @maxrd: read limitations
* @maxrdturn: maximum read turn-around expressed micro-seconds and
* little-endian formatted
*/
-struct i3c_ccc_getmxds {
+struct i3c_ccc_getmxds_turnaround {
u8 maxwr;
u8 maxrd;
u8 maxrdturn[3];
--
2.25.1
--
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reply other threads:[~2023-08-28 15:21 UTC|newest]
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