Re: [PATCH v8] i2c: riic: Implement bus recovery

[Lad, Prabhakar]

Hi Wolfram,

On Wed, Apr 23, 2025 at 9:26 AM Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
>
>
> > Well, frankly, this is the only test I tried and, yes, it did work for
> > me. Will check 'incomplete_write_byte' later today. I will also check if
> > I need to run the tests more often. I did not do an endless loop.
>
> Both tests work for me, even in an endless loop. I also get the desired
> signal outputs checking with the logic analyzer.
>
> Here is the branch I used:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/g3s/riic-recovery-experimental
>
I prepared a setup on SMARC2 RZ/G3S and I can confirm it is working
(but this is failing on SMARC RZ/G2L I'll look further into this)

For the SMARC2 RZ/G3S to make sure the I2C GPIO pins behave as
opendrain I have the below patch for pinctrl

 drivers/pinctrl/renesas/pinctrl-rzg2l.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
index 78fa08ff0faa..04bbc7499ce9 100644
--- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
+++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
@@ -167,6 +167,7 @@
 #define NOD_MASK        0x01
 #define SMT_MASK        0x01

+#define PM_HI_Z         0x0
 #define PM_INPUT        0x1
 #define PM_OUTPUT        0x2

@@ -176,6 +177,9 @@
 #define RZG2L_TINT_MAX_INTERRUPT    32
 #define RZG2L_PACK_HWIRQ(t, i)        (((t) << 16) | (i))

+#define GPIO8_P8_2        66
+#define GPIO8_P8_3        67
+
 /* Custom pinconf parameters */
 #define RENESAS_RZV2H_PIN_CONFIG_OUTPUT_IMPEDANCE    (PIN_CONFIG_END + 1)

@@ -1703,6 +1707,10 @@ static int rzg2l_gpio_request(struct gpio_chip
*chip, unsigned int offset)
     pctrl->data->pmc_writeb(pctrl, reg8, PMC(off));

     spin_unlock_irqrestore(&pctrl->lock, flags);
+    if (offset == GPIO8_P8_2 || offset == GPIO8_P8_3) {
+        rzg2l_rmw_pin_config(pctrl, PUPD(off), bit, PUPD_MASK, 1);
+        rzg2l_rmw_pin_config(pctrl, IOLH(off), bit, IOLH_MASK, 0x3);
+    }

     return 0;
 }
@@ -1722,7 +1730,10 @@ static void rzg2l_gpio_set_direction(struct
rzg2l_pinctrl *pctrl, u32 offset,
     reg16 = readw(pctrl->base + PM(off));
     reg16 &= ~(PM_MASK << (bit * 2));

-    reg16 |= (output ? PM_OUTPUT : PM_INPUT) << (bit * 2);
+    if (offset == GPIO8_P8_2 || offset == GPIO8_P8_3)
+        reg16 |= (output ? PM_OUTPUT : PM_HI_Z) << (bit * 2);
+    else
+        reg16 |= (output ? PM_OUTPUT : PM_INPUT) << (bit * 2);
     writew(reg16, pctrl->base + PM(off));

     spin_unlock_irqrestore(&pctrl->lock, flags);
@@ -1769,6 +1780,11 @@ static void rzg2l_gpio_set(struct gpio_chip
*chip, unsigned int offset,
     unsigned long flags;
     u8 reg8;

+       if (offset == GPIO8_P8_2 || offset == GPIO8_P8_3) {
+               rzg2l_gpio_set_direction(pctrl, offset, value ? 0 : 1);
+               return;
+       }
+
     spin_lock_irqsave(&pctrl->lock, flags);

     reg8 = readb(pctrl->base + P(off));
@@ -1804,6 +1820,12 @@ static int rzg2l_gpio_get(struct gpio_chip
*chip, unsigned int offset)
     reg16 = readw(pctrl->base + PM(off));
     reg16 = (reg16 >> (bit * 2)) & PM_MASK;

+       if (offset == GPIO8_P8_2 || offset == GPIO8_P8_3) {
+               if (reg16 == PM_HI_Z)
+                       return 1;
+               return 0;
+       }
+
     if (reg16 == PM_INPUT)
         return !!(readb(pctrl->base + PIN(off)) & BIT(bit));
     else if (reg16 == PM_OUTPUT)

--
2.49.0

Below is my loop tests for SMARC2 RZ/G3S which worked without any issues:
root@smarc-rzg3s:~/i2c# cat ./i2c-inject-error.sh
DEFAULT_LOOP_COUNT=500

incomplete_address_phase() {
        cd /sys/kernel/debug/i2c/i2c-2/
        for i in {1..1}; do
                echo 0x1a > incomplete_address_phase;
                val=$(i2cget -y -f 0 0x1a 3)
                if [ "$?" != "0" ] || [ "${val}" != "0x0c" ]; then
                        echo "I2C Read error (ret:$?) ${val}!!"
                        exit 1
                fi
                echo "Read val:${val}"
                i2cget -y -f 0 0x1a 3;
                if [ "$?" != "0" ]; then
                        echo "I2C Read error when no error injection!!"
                        exit 1
                fi
        done
}

incomplete_write_byte() {
        cd /sys/kernel/debug/i2c/i2c-2/
        for i in {1..1}; do
                val1=$(printf "0x%02x" $((RANDOM & 0xff)))
                val2=$(printf "0x%02x" $((RANDOM & 0xff)))
                i2cset -y -f 0 0x57 0 ${val1}
                i2cset -y -f 0 0x57 8 ${val2}
                r1=$(i2cget -y -f 0 0x57 0x0)
                if [ "$?" != "0" ] || [ "${r1}" != "${val1}" ]; then
                        echo "1: I2C Read error (ret:$?) ${r1}!!"
                        exit 1
                fi
                echo 0x57 > incomplete_write_byte
                r1=$(i2cget -y -f 0 0x57 0x8)
                if [ "$?" != "0" ] || [ "${r1}" != "${val2}" ]; then
                        echo "2: I2C Read error (ret:$?) ${r1}!!"
                        exit 1
                fi
                r1=$(i2cget -y -f 0 0x57 0x0)
                if [ "$?" != "0" ] || [ "${r1}" != "${val1}" ]; then
                        echo "3: I2C Read error (ret:$?) ${r1}!!"
                        exit 1
                fi
        done
}


if [ ! -z "${1}" ];then
        DEFAULT_LOOP_COUNT=$1
fi

for i in $(seq 0 $DEFAULT_LOOP_COUNT);do
        echo "Loop count: "$i;
        incomplete_address_phase
        incomplete_write_byte
done

root@smarc-rzg3s:~/i2c#

Ive attached the analyzer for SMARC RZ/G2L where it is failing for
`incomplete_address_phase`.

Cheers,
Prabhakar

Attachment: trigger-incomplete-address.png
Description: PNG image

Attachment: recovery-trigger.png
Description: PNG image