Commit 2aac0bf4 authored by Joshua Yeong's avatar Joshua Yeong Committed by Alexandre Belloni
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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: default avatarJoshua Yeong <joshua.yeong@starfivetech.com>
Reviewed-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20231114085525.6271-2-joshua.yeong@starfivetech.com


Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 4afd7287

drivers/i3c/master.c

+10 −2
Original line number Diff line number Diff line
@@ -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) {

		/*

		 * 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;