| Message ID | 20231114085525.6271-2-joshua.yeong@starfivetech.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | Fallback mechanism for GETMXDS CCC | expand |
Hi Joshua, joshua.yeong@starfivetech.com wrote on Tue, 14 Nov 2023 16:55:25 +0800: > Some I3C hardware will report error when an incorrect length is received from > device. GETMXDS CCC are available 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. So in case sending GETMXDS CCC format 2 resulted > in a failure, try sending GETMXDS CCC format 1 instead. > Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com> > Signed-off-by: Joshua Yeong <joshua.yeong@starfivetech.com> > --- Thanks, Miquèl
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 95caa162706f..718b643cb54d 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -1130,8 +1130,16 @@ 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;
Some I3C hardware will report error when an incorrect length is received from device. GETMXDS CCC are available 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. So in case sending GETMXDS CCC format 2 resulted in a 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(-)