There is a long standing bug which causes I2C communication not to work on the Armada 3700 based boards. This small series restores that functionality.
Signed-off-by: Gabor Juhos j4g8y7@gmail.com Signed-off-by: Imre Kaloz kaloz@openwrt.org --- Gabor Juhos (3): i2c: add init_recovery() callback i2c: pxa: prevent calling of the generic recovery init code i2c: pxa: handle 'Early Bus Busy' condition on Armada 3700
drivers/i2c/busses/i2c-pxa.c | 25 +++++++++++++++++++------ drivers/i2c/i2c-core-base.c | 8 +++++++- include/linux/i2c.h | 4 ++++ 3 files changed, 30 insertions(+), 7 deletions(-) --- base-commit: 92a09c47464d040866cf2b4cd052bc60555185fb change-id: 20250510-i2c-pxa-fix-i2c-communication-3e6de1e3d0c6
Best regards,
Add a new init_recovery() callback to struct 'i2c_bus_recovery_info' and modify the i2c_init_recovery() function to call that if specified instead of the generic i2c_gpio_init_recovery() function.
This allows controller drivers to skip calling the generic code by implementing a dummy callback function, or alternatively to run a fine tuned custom implementation.
This is needed for the 'i2c-pxa' driver in order to be able to fix a long standing bug for which the fix will be implemented in a followup patch.
Cc: stable@vger.kernel.org # 6.3+ Signed-off-by: Gabor Juhos j4g8y7@gmail.com Signed-off-by: Imre Kaloz kaloz@openwrt.org --- drivers/i2c/i2c-core-base.c | 8 +++++++- include/linux/i2c.h | 4 ++++ 2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 7ad1ad5c8c3f56943b627254b1fdbf8f787afdb5..6b8b961b845caf6f28ea1a9a76d623ac73f5e0dd 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -427,12 +427,18 @@ static int i2c_init_recovery(struct i2c_adapter *adap) struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; bool is_error_level = true; char *err_str; + int ret;
if (!bri) return 0;
- if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER) + if (bri->init_recovery) { + ret = bri->init_recovery(adap); + if (ret) + return ret; + } else if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER) { return -EPROBE_DEFER; + }
if (!bri->recover_bus) { err_str = "no suitable method provided"; diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 2e4903b7f7bc11627f9cbc23a4d549dd48c4dcc7..1cff399822c817429e520572546a3d0b7f704723 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -638,6 +638,9 @@ struct i2c_timings { * for generic GPIO recovery. * @get_bus_free: Returns the bus free state as seen from the IP core in case it * has a more complex internal logic than just reading SDA. Optional. + * @init_recovery: If specified, it will be called instead of the generic GPIO + * recovery initialization code. Platform may use a dummy callback to skip + * calling the generic code, or it may use a custom implementation. * @prepare_recovery: This will be called before starting recovery. Platform may * configure padmux here for SDA/SCL line or something else they want. * @unprepare_recovery: This will be called after completing recovery. Platform @@ -662,6 +665,7 @@ struct i2c_bus_recovery_info { void (*set_sda)(struct i2c_adapter *adap, int val); int (*get_bus_free)(struct i2c_adapter *adap);
+ int (*init_recovery)(struct i2c_adapter *adap); void (*prepare_recovery)(struct i2c_adapter *adap); void (*unprepare_recovery)(struct i2c_adapter *adap);
Szía Gabor,
köszönöm a patch-et!
On Sun, May 11, 2025 at 3:31 PM Gabor Juhos j4g8y7@gmail.com wrote:
Add a new init_recovery() callback to struct 'i2c_bus_recovery_info' and modify the i2c_init_recovery() function to call that if specified instead of the generic i2c_gpio_init_recovery() function.
This allows controller drivers to skip calling the generic code by implementing a dummy callback function, or alternatively to run a fine tuned custom implementation.
This is needed for the 'i2c-pxa' driver in order to be able to fix a long standing bug for which the fix will be implemented in a followup patch.
Cc: stable@vger.kernel.org # 6.3+ Signed-off-by: Gabor Juhos j4g8y7@gmail.com Signed-off-by: Imre Kaloz kaloz@openwrt.org
Clearly, since the same problems keeps appearing on other platforms as well, this is the right way to go! Reviewed-by: Linus Walleij linus.walleij@linaro.org
Yours, Linus Walleij
The I2C communication is completely broken on the Armada 3700 platform since commit 0b01392c18b9 ("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 7b211c767121 ("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 20cb3fce4d60 ("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 conrtoller is getting enabled in i2c_pxa_reset(), whereas in the case of the generic initialization it happens after that.
To resolve the problem, provide an empty init_recovery() callback function thus preventing the I2C core to call the generic recovery initialization code.
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:
[ 7.305277] i2c i2c-0: PXA I2C adapter [ 7.310198] i2c i2c-1: PXA I2C adapter [ 7.315012] sfp sfp-eth1: Host maximum power 3.0W [ 7.324061] lm75 1-0048: supply vs not found, using dummy regulator [ 7.331738] sfp sfp-eth0: Host maximum power 3.0W [ 7.337000] hwmon hwmon0: temp1_input not attached to any thermal zone [ 7.343593] lm75 1-0048: hwmon0: sensor 'tmp75c' [ 7.348526] lm75 1-0049: supply vs not found, using dummy regulator [ 7.356858] hwmon hwmon1: temp1_input not attached to any thermal zone [ 7.363463] lm75 1-0049: hwmon1: sensor 'tmp75c' ... [ 7.730315] sfp sfp-eth1: module Mikrotik S-RJ01 rev 1.0 sn 61B103C55C58 dc 201022 [ 7.840318] sfp sfp-eth0: module MENTECHOPTO POS22-LDCC-KR rev 1.0 sn MNC208U90009 dc 200828 [ 7.850083] mvneta d0030000.ethernet eth0: unsupported SFP module: no common interface modes [ 7.990335] hwmon hwmon2: temp1_input not attached to any thermal zone
[1] https://lore.kernel.org/r/20230926160255.330417-1-robert.marko@sartura.hr
Cc: stable@vger.kernel.org # 6.3+ Fixes: 20cb3fce4d60 ("i2c: Set i2c pinctrl recovery info from it's device pinctrl") Signed-off-by: Gabor Juhos j4g8y7@gmail.com Signed-off-by: Imre Kaloz kaloz@openwrt.org --- drivers/i2c/busses/i2c-pxa.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c index 4415a29f749b927ce96e54cfbd229e1f48fa8623..a36fc30e6f262f0608e0bc77d02771d13d0e0921 100644 --- a/drivers/i2c/busses/i2c-pxa.c +++ b/drivers/i2c/busses/i2c-pxa.c @@ -1330,6 +1330,12 @@ static void i2c_pxa_unprepare_recovery(struct i2c_adapter *adap) i2c_pxa_enable(i2c); }
+static int i2c_pxa_init_recovery_cb(struct i2c_adapter *adap) +{ + /* We have initialized everything already, so nothing to do here. */ + return 0; +} + static int i2c_pxa_init_recovery(struct pxa_i2c *i2c) { struct i2c_bus_recovery_info *bri = &i2c->recovery; @@ -1398,6 +1404,7 @@ static int i2c_pxa_init_recovery(struct pxa_i2c *i2c) return 0; }
+ bri->init_recovery = i2c_pxa_init_recovery_cb; bri->prepare_recovery = i2c_pxa_prepare_recovery; bri->unprepare_recovery = i2c_pxa_unprepare_recovery; bri->recover_bus = i2c_generic_scl_recovery;
Under some circumstances I2C recovery fails on Armada 3700. At least on the Methode uDPU board, removing and replugging an SFP module fails often, like this:
[ 36.953127] sfp sfp-eth1: module removed [ 38.468549] i2c i2c-1: i2c_pxa: timeout waiting for bus free [ 38.486960] sfp sfp-eth1: module MENTECHOPTO POS22-LDCC-KR rev 1.0 sn MNC208U90009 dc 200828 [ 38.496867] mvneta d0040000.ethernet eth1: unsupported SFP module: no common interface modes [ 38.521448] hwmon hwmon2: temp1_input not attached to any thermal zone [ 39.249196] sfp sfp-eth1: module removed ... [ 292.568799] sfp sfp-eth1: please wait, module slow to respond ... [ 625.208814] sfp sfp-eth1: failed to read EEPROM: -EREMOTEIO
Note that the 'unsupported SFP module' messages are not relevant. The module is used only for testing the I2C recovery funcionality, because the error can be triggered easily with this specific one.
Enabling debug in the i2c-pxa driver reveals the following:
[ 82.034678] sfp sfp-eth1: module removed [ 90.008654] i2c i2c-1: slave_0x50 error: timeout with active message [ 90.015112] i2c i2c-1: msg_num: 2 msg_idx: 0 msg_ptr: 0 [ 90.020464] i2c i2c-1: IBMR: 00000003 IDBR: 000000a0 ICR: 000007e0 ISR: 00000802 [ 90.027906] i2c i2c-1: log: [ 90.030787]
This continues until the retries are exhausted ...
[ 110.192489] i2c i2c-1: slave_0x50 error: exhausted retries [ 110.198012] i2c i2c-1: msg_num: 2 msg_idx: 0 msg_ptr: 0 [ 110.203323] i2c i2c-1: IBMR: 00000003 IDBR: 000000a0 ICR: 000007e0 ISR: 00000802 [ 110.210810] i2c i2c-1: log: [ 110.213633]
... then the whole sequence starts again ...
[ 115.368641] i2c i2c-1: slave_0x50 error: timeout with active message
... while finally the SFP core gives up:
[ 671.975258] sfp sfp-eth1: failed to read EEPROM: -EREMOTEIO
When we analyze the log, it can be seen that bit 1 and 11 is set in the ISR (Interface Status Register). Bit 1 indicates the ACK/NACK status, but the purpose of bit 11 is not documented in the driver code unfortunately.
The 'Functional Specification' document of the Armada 3700 SoCs family however says that this bit indicates an 'Early Bus Busy' condition. The document also notes that whenever this bit is set, it is not possible to initiate a transaction on the I2C bus. The observed behaviour corresponds to this statement.
Unfortunately, I2C recovery does not help as it never runs in this special case. Although the driver checks the busyness of the bus at several places, but since it does not consider the A3700 specific bit in these checks it can't determine the actual status of the bus correctly which results in the errors above.
In order to fix the problem, add a new member to struct 'i2c_pxa' to store a controller specific bitmask containing the bits indicating the busy status, and use that in the code while checking the actual status of the bus. This ensures that the correct status can be determined on the Armada 3700 based devices without causing functional changes on devices based on other SoCs.
With the change applied, the driver detects the busy condition, and runs the recovery process:
[ 742.617312] i2c i2c-1: state:i2c_pxa_wait_bus_not_busy:449: ISR=00000802, ICR=000007e0, IBMR=03 [ 742.626099] i2c i2c-1: i2c_pxa: timeout waiting for bus free [ 742.631933] i2c i2c-1: recovery: resetting controller, ISR=0x00000802 [ 742.638421] i2c i2c-1: recovery: IBMR 0x00000003 ISR 0x00000000
This clears the EBB bit in the ISR register, so it makes it possible to initiate transactions on the I2C bus again.
After this patch, the SFP module used for testing can be removed and replugged numerous times without causing the error described at the beginning. Previously, the error happened after a few such attempts.
The patch has been tested also with the following kernel versions: 5.10.237, 5.15.182, 6.1.138, 6.6.90, 6.12.28, 6.14.6. It improves recoverabilty on all of them.
Cc: stable@vger.kernel.org # 5.8+ Fixes: 7c9ec2c52518 ("i2c: pxa: implement generic i2c bus recovery") Signed-off-by: Gabor Juhos j4g8y7@gmail.com Signed-off-by: Imre Kaloz kaloz@openwrt.org --- Note: the patch is included in this series for completeness however it can be applied independently from the preceding patches. On kernels 6.3+, it restores I2C functionality even in itself because it recovers the controller from the bad state described in the previous patch. --- drivers/i2c/busses/i2c-pxa.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c index a36fc30e6f262f0608e0bc77d02771d13d0e0921..5196389428b21b7d15569e7469380bf190f46d67 100644 --- a/drivers/i2c/busses/i2c-pxa.c +++ b/drivers/i2c/busses/i2c-pxa.c @@ -71,6 +71,7 @@ #define ISR_GCAD (1 << 8) /* general call address detected */ #define ISR_SAD (1 << 9) /* slave address detected */ #define ISR_BED (1 << 10) /* bus error no ACK/NAK */ +#define ISR_A3700_EBB (1 << 11) /* early bus busy for armada 3700 */
#define ILCR_SLV_SHIFT 0 #define ILCR_SLV_MASK (0x1FF << ILCR_SLV_SHIFT) @@ -263,6 +264,7 @@ struct pxa_i2c { bool highmode_enter; u32 fm_mask; u32 hs_mask; + u32 busy_mask;
struct i2c_bus_recovery_info recovery; struct pinctrl *pinctrl; @@ -429,7 +431,7 @@ static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
while (1) { isr = readl(_ISR(i2c)); - if (!(isr & (ISR_IBB | ISR_UB))) + if (!(isr & i2c->busy_mask)) return 0;
if (isr & ISR_SAD) @@ -466,7 +468,7 @@ static int i2c_pxa_wait_master(struct pxa_i2c *i2c) * quick check of the i2c lines themselves to ensure they've * gone high... */ - if ((readl(_ISR(i2c)) & (ISR_UB | ISR_IBB)) == 0 && + if ((readl(_ISR(i2c)) & i2c->busy_mask) == 0 && readl(_IBMR(i2c)) == (IBMR_SCLS | IBMR_SDAS)) { if (i2c_debug > 0) dev_dbg(&i2c->adap.dev, "%s: done\n", __func__); @@ -487,7 +489,7 @@ static int i2c_pxa_set_master(struct pxa_i2c *i2c) if (i2c_debug) dev_dbg(&i2c->adap.dev, "setting to bus master\n");
- if ((readl(_ISR(i2c)) & (ISR_UB | ISR_IBB)) != 0) { + if ((readl(_ISR(i2c)) & i2c->busy_mask) != 0) { dev_dbg(&i2c->adap.dev, "%s: unit is busy\n", __func__); if (!i2c_pxa_wait_master(i2c)) { dev_dbg(&i2c->adap.dev, "%s: error: unit busy\n", __func__); @@ -513,7 +515,7 @@ static int i2c_pxa_wait_slave(struct pxa_i2c *i2c) dev_dbg(&i2c->adap.dev, "%s: %ld: ISR=%08x, ICR=%08x, IBMR=%02x\n", __func__, (long)jiffies, readl(_ISR(i2c)), readl(_ICR(i2c)), readl(_IBMR(i2c)));
- if ((readl(_ISR(i2c)) & (ISR_UB|ISR_IBB)) == 0 || + if ((readl(_ISR(i2c)) & i2c->busy_mask) == 0 || (readl(_ISR(i2c)) & ISR_SAD) != 0 || (readl(_ICR(i2c)) & ICR_SCLE) == 0) { if (i2c_debug > 1) @@ -1171,7 +1173,7 @@ static int i2c_pxa_pio_set_master(struct pxa_i2c *i2c) /* * Wait for the bus to become free. */ - while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) + while (timeout-- && readl(_ISR(i2c)) & i2c->busy_mask) udelay(1000);
if (timeout < 0) { @@ -1316,7 +1318,7 @@ static void i2c_pxa_unprepare_recovery(struct i2c_adapter *adap) * handing control of the bus back to avoid the bus changing state. */ isr = readl(_ISR(i2c)); - if (isr & (ISR_UB | ISR_IBB)) { + if (isr & i2c->busy_mask) { dev_dbg(&i2c->adap.dev, "recovery: resetting controller, ISR=0x%08x\n", isr); i2c_pxa_do_reset(i2c); @@ -1480,6 +1482,10 @@ static int i2c_pxa_probe(struct platform_device *dev) i2c->fm_mask = pxa_reg_layout[i2c_type].fm; i2c->hs_mask = pxa_reg_layout[i2c_type].hs;
+ i2c->busy_mask = ISR_UB | ISR_IBB; + if (i2c_type == REGS_A3700) + i2c->busy_mask |= ISR_A3700_EBB; + if (i2c_type != REGS_CE4100) i2c->reg_isar = i2c->reg_base + pxa_reg_layout[i2c_type].isar;
linux-stable-mirror@lists.linaro.org
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Gabor Juhos -
Linus Walleij