Messages in this thread Patch in this message | | | From | Joshua Yeong <> | Subject | [PATCH 1/1] i3c: Add fallback method for GETMXDS CCC | Date | Mon, 11 Sep 2023 16:24:56 +0800 |
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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 87283e4a4607..084f64bef155 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -1088,10 +1088,37 @@ 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) @@ -1102,17 +1129,13 @@ 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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