From: Joshua Yeong Date: Tue, 14 Nov 2023 08:55:25 +0000 (+0800) Subject: i3c: Add fallback method for GETMXDS CCC X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2aac0bf4ebc8e09941bb2a40c0ce725437d9a82c;p=linux.git i3c: Add fallback method for GETMXDS CCC 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 Reviewed-by: Miquel Raynal Link: https://lore.kernel.org/r/20231114085525.6271-2-joshua.yeong@starfivetech.com Signed-off-by: Alexandre Belloni --- diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index 95caa162706f5..718b643cb54dd 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;