i2c: pxa: defer reset on Armada 3700 when recovery is used

The I2C communication is completely broken on the Armada 3700 platform
since commit 0b01392 ("i2c: pxa: move to generic GPIO recovery").

For example, on the Methode uDPU board, probing of the two onboard
temperature sensors fails ...

  [    7.271713] i2c i2c-0: using pinctrl states for GPIO recovery
  [    7.277503] i2c i2c-0:  PXA I2C adapter
  [    7.282199] i2c i2c-1: using pinctrl states for GPIO recovery
  [    7.288241] i2c i2c-1:  PXA I2C adapter
  [    7.292947] sfp sfp-eth1: Host maximum power 3.0W
  [    7.299614] sfp sfp-eth0: Host maximum power 3.0W
  [    7.308178] lm75 1-0048: supply vs not found, using dummy regulator
  [   32.489631] lm75 1-0048: probe with driver lm75 failed with error -121
  [   32.496833] lm75 1-0049: supply vs not found, using dummy regulator
  [   82.890614] lm75 1-0049: probe with driver lm75 failed with error -121

... and accessing the plugged-in SFP modules also does not work:

  [  511.298537] sfp sfp-eth1: please wait, module slow to respond
  [  536.488530] sfp sfp-eth0: please wait, module slow to respond
  ...
  [ 1065.688536] sfp sfp-eth1: failed to read EEPROM: -EREMOTEIO
  [ 1090.888532] sfp sfp-eth0: failed to read EEPROM: -EREMOTEIO

After a discussion [1], there was an attempt to fix the problem by
reverting the offending change by commit 7b211c7 ("Revert "i2c:
pxa: move to generic GPIO recovery""), but that only helped to fix
the issue in the 6.1.y stable tree. The reason behind the partial succes
is that there was another change in commit 20cb3fc ("i2c: Set i2c
pinctrl recovery info from it's device pinctrl") in the 6.3-rc1 cycle
which broke things further.

The cause of the problem is the same in case of both offending commits
mentioned above. Namely, the I2C core code changes the pinctrl state to
GPIO while running the recovery initialization code. Although the PXA
specific initialization also does this, but the key difference is that
it happens before the controller is getting enabled in i2c_pxa_reset(),
whereas in the case of the generic initialization it happens after that.

Change the code to reset the controller only before the first transfer
instead of before registering the controller. This ensures that the
controller is not enabled at the time when the generic recovery code
performs the pinctrl state changes, thus avoids the problem described
above.

As the result this change restores the original behaviour, which in
turn makes the I2C communication to work again as it can be seen from
the following log:

  [    7.363250] i2c i2c-0: using pinctrl states for GPIO recovery
  [    7.369041] i2c i2c-0:  PXA I2C adapter
  [    7.373673] i2c i2c-1: using pinctrl states for GPIO recovery
  [    7.379742] i2c i2c-1:  PXA I2C adapter
  [    7.384506] sfp sfp-eth1: Host maximum power 3.0W
  [    7.393013] sfp sfp-eth0: Host maximum power 3.0W
  [    7.399266] lm75 1-0048: supply vs not found, using dummy regulator
  [    7.407257] hwmon hwmon0: temp1_input not attached to any thermal zone
  [    7.413863] lm75 1-0048: hwmon0: sensor 'tmp75c'
  [    7.418746] lm75 1-0049: supply vs not found, using dummy regulator
  [    7.426371] hwmon hwmon1: temp1_input not attached to any thermal zone
  [    7.432972] lm75 1-0049: hwmon1: sensor 'tmp75c'
  [    7.755092] sfp sfp-eth1: module MENTECHOPTO      POS22-LDCC-KR    rev 1.0  sn MNC208U90009     dc 200828
  [    7.764997] mvneta d0040000.ethernet eth1: unsupported SFP module: no common interface modes
  [    7.785362] sfp sfp-eth0: module Mikrotik         S-RJ01           rev 1.0  sn 61B103C55C58     dc 201022
  [    7.803426] hwmon hwmon2: temp1_input not attached to any thermal zone

Link: https://lore.kernel.org/r/[email protected] #1

Cc: [email protected] # 6.3+
Fixes: 20cb3fc ("i2c: Set i2c pinctrl recovery info from it's device pinctrl")
Signed-off-by: Gabor Juhos <[email protected]>
Tested-by: Robert Marko <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>
Signed-off-by: Andi Shyti <[email protected]>
Link: https://lore.kernel.org/r/20260226-i2c-pxa-fix-i2c-communication-v4-1-797a091dae87@gmail.com

Author: juhosg

drivers/i2c/busses/i2c-pxa.c

@@ -268,6 +268,7 @@ struct pxa_i2c {
 	struct pinctrl		*pinctrl;
 	struct pinctrl_state	*pinctrl_default;
 	struct pinctrl_state	*pinctrl_recovery;
+	bool			reset_before_xfer;
 };
 
 #define _IBMR(i2c)	((i2c)->reg_ibmr)
@@ -1144,6 +1145,11 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap,
 {
 	struct pxa_i2c *i2c = adap->algo_data;
 
+	if (i2c->reset_before_xfer) {
+		i2c_pxa_reset(i2c);
+		i2c->reset_before_xfer = false;
+	}
+
 	return i2c_pxa_internal_xfer(i2c, msgs, num, i2c_pxa_do_xfer);
 }
 
@@ -1521,7 +1527,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
 		}
 	}
 
-	i2c_pxa_reset(i2c);
+	/*
+	 * Skip reset on Armada 3700 when recovery is used to avoid
+	 * controller hang due to the pinctrl state changes done by
+	 * the generic recovery initialization code. The reset will
+	 * be performed later, prior to the first transfer.
+	 */
+	if (i2c_type == REGS_A3700 && i2c->adap.bus_recovery_info)
+		i2c->reset_before_xfer = true;
+	else
+		i2c_pxa_reset(i2c);
 
 	ret = i2c_add_numbered_adapter(&i2c->adap);
 	if (ret < 0)