Messages in this thread Patch in this message | | | From | Joshua Yeong <> | Subject | [PATCH v2 1/1] i3c: Add fallback method for GETMXDS CCC | Date | Tue, 14 Nov 2023 11:34:30 +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 | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 0cdc94e4cb77..2fc04d97f07e 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -1099,8 +1099,16 @@ static int i3c_master_getmxds_locked(struct i3c_master_controller *master, i3c_ccc_cmd_init(&cmd, true, I3C_CCC_GETMXDS, &dest, 1); ret = i3c_master_send_ccc_cmd_locked(master, &cmd); - if (ret) - goto out; + if (ret) { + /* + * Retry when the device does not support max read turnaround + * while expecting shorter length from this CCC command + */ + dest->payload.len -= 3; + ret = i3c_master_send_ccc_cmd_locked(master, &cmd); + if (ret) + goto out; + } if (dest.payload.len != 2 && dest.payload.len != 5) { ret = -EIO; -- 2.25.1
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