diff mbox series

[v3,1/1] i3c: master: svc: fix probe failure when no i3c device exist

Message ID 20230831141324.2841525-1-Frank.Li@nxp.com (mailing list archive)
State Accepted
Headers show
Series [v3,1/1] i3c: master: svc: fix probe failure when no i3c device exist | expand

Commit Message

Frank Li Aug. 31, 2023, 2:13 p.m. UTC
I3C masters are expected to support hot-join. This means at initialization
time we might not yet discover any device and this should not be treated
as a fatal error.

During the DAA procedure which happens at probe time, if no device has
joined, all CCC will be NACKed (from a bus perspective). This leads to an
early return with an error code which fails the probe of the master.

Let's avoid this by just telling the core through an I3C_ERROR_M2
return command code that no device was discovered, which is a valid
situation. This way the master will no longer bail out and fail to probe
for a wrong reason.

Cc: stable@vger.kernel.org
Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---

Notes:
    Change from v3 to v3
    - No code change
    - Remove patch i3c: master: fixes i3c bus driver probe failure if no i3c
    device attached
    - After test, only need this patch to fix probe failure because
    i3c_master_rstdaa_locked() already correct handle error code.
    
    Change from v1 to v2:
    - rewrite commit message
    - cc stable
    - add empty line in daa()

 drivers/i3c/master/svc-i3c-master.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

Comments

Miquel Raynal Aug. 31, 2023, 2:21 p.m. UTC | #1
Hi Frank,

Frank.Li@nxp.com wrote on Thu, 31 Aug 2023 10:13:24 -0400:

> I3C masters are expected to support hot-join. This means at initialization
> time we might not yet discover any device and this should not be treated
> as a fatal error.
> 
> During the DAA procedure which happens at probe time, if no device has
> joined, all CCC will be NACKed (from a bus perspective). This leads to an
> early return with an error code which fails the probe of the master.
> 
> Let's avoid this by just telling the core through an I3C_ERROR_M2
> return command code that no device was discovered, which is a valid
> situation. This way the master will no longer bail out and fail to probe
> for a wrong reason.
> 
> Cc: stable@vger.kernel.org
> Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
> Signed-off-by: Frank Li <Frank.Li@nxp.com>

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

Thanks,
Miquèl
Alexandre Belloni Sept. 5, 2023, 11:22 p.m. UTC | #2
On Thu, 31 Aug 2023 10:13:24 -0400, Frank Li wrote:
> I3C masters are expected to support hot-join. This means at initialization
> time we might not yet discover any device and this should not be treated
> as a fatal error.
> 
> During the DAA procedure which happens at probe time, if no device has
> joined, all CCC will be NACKed (from a bus perspective). This leads to an
> early return with an error code which fails the probe of the master.
> 
> [...]

Applied, thanks!

[1/1] i3c: master: svc: fix probe failure when no i3c device exist
      commit: 6e13d6528be2f7e801af63c8153b87293f25d736

Best regards,
diff mbox series

Patch

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index 770b40e28015e..cf932ee056ef9 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -789,6 +789,10 @@  static int svc_i3c_master_do_daa_locked(struct svc_i3c_master *master,
 				 */
 				break;
 			} else if (SVC_I3C_MSTATUS_NACKED(reg)) {
+				/* No I3C devices attached */
+				if (dev_nb == 0)
+					break;
+
 				/*
 				 * A slave device nacked the address, this is
 				 * allowed only once, DAA will be stopped and
@@ -1263,11 +1267,17 @@  static int svc_i3c_master_send_ccc_cmd(struct i3c_master_controller *m,
 {
 	struct svc_i3c_master *master = to_svc_i3c_master(m);
 	bool broadcast = cmd->id < 0x80;
+	int ret;
 
 	if (broadcast)
-		return svc_i3c_master_send_bdcast_ccc_cmd(master, cmd);
+		ret = svc_i3c_master_send_bdcast_ccc_cmd(master, cmd);
 	else
-		return svc_i3c_master_send_direct_ccc_cmd(master, cmd);
+		ret = svc_i3c_master_send_direct_ccc_cmd(master, cmd);
+
+	if (ret)
+		cmd->err = I3C_ERROR_M2;
+
+	return ret;
 }
 
 static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev,