Regression: at24 eeprom writing times out on sama5d3

[Peter Rosin]

Hi!

I have not actually bisected this issue but reverting the effects of
patch a4bd8da893a3 ("ARM: dts: at91: sama5d3: add i2c gpio pinctrl")
makes the problem go away.

I.e. I need something like this in my dts

&i2c2 {
	status = "okay";

	pinctrl-names = "default";
	/delete-property/ pinctrl-1;
	/delete-property/ sda-gpios;
	/delete-property/ scl-gpios;

	eeprom at 50 {
		compatible = "st,24c64", "atmel,24c64";
		reg = <0x50>;
		wp-gpios = <&filter_gpio 7 GPIO_ACTIVE_HIGH>;
	};
};

for multi-page eeprom writes to not time out (a page is 32 bytes on this
eeprom).

For reference, the current defaults for this SoC/I2C-bus, that I modify,
are:

	pinctrl-names = "default", "gpio";
	pinctrl-0 = <&pinctrl_i2c2>;
	pinctrl-1 = <&pinctrl_i2c2_gpio>;
	sda-gpios = <&pioA 18 GPIO_ACTIVE_HIGH>;
	scl-gpios = <&pioA 19 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;

I suspect that the underlying reason is that the bus recovery takes
too long and that the at24 eeprom driver gives up prematurely. I doubt
that this is chip specific, but I don't know that.

I can work around the issue in user space with by writing in 4 byte
chunks, like so

dd if=source.file of=/sys/bus/i2c/devices/2-0050/eeprom obs=4

but that is really ugly and gets slow too, about 20 seconds to program
the full 8kB eeprom. With the above in my dts it takes a second or
so (a bit more with dynamic debug active).


If I run

dd if=source.file of=/sys/bus/i2c/devices/2-0050/eeprom

with a source.file of 8kB and the upstream dts properties in place, I can
collect the following debug output from at24, i2c-core and i2c-at91:

Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 0 --> 0 (-23170)
Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:56:34 me20 kernel: i2c i2c-2: Trying i2c bus recovery
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 32 --> -121 (-23169)
Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 32 --> 0 (-23168)
Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:56:34 me20 kernel: i2c i2c-2: Trying i2c bus recovery
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 64 --> -121 (-23168)
Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 64 --> 0 (-23167)
Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:56:34 me20 kernel: i2c i2c-2: Trying i2c bus recovery
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 96 --> -121 (-23167)
Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: controller timed out
Jun  9 15:56:34 me20 kernel: i2c i2c-2: Trying i2c bus recovery
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 96 --> -110 (-23155)
Jun  9 15:56:34 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:56:34 me20 kernel: at91_i2c f801c000.i2c: controller timed out
Jun  9 15:56:34 me20 kernel: i2c i2c-2: Trying i2c bus recovery
Jun  9 15:56:34 me20 kernel: at24 2-0050: write 32 at 96 --> -110 (-23143)

And then there is no more action. I.e. only a couple of 32 byte pages
are written.

With the above mentioned dts override in place I instead get this, which is
a lot more sensible:

Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 0 --> 0 (753629)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 32 --> -121 (753629)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 32 --> 0 (753630)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 64 --> -121 (753630)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 64 --> 0 (753631)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 96 --> -121 (753631)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 96 --> 0 (753632)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 128 --> -121 (753632)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 128 --> 0 (753633)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 160 --> -121 (753633)
Jun  9 15:48:53 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:53 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:53 me20 kernel: at24 2-0050: write 32 at 160 --> 0 (753634)
... snip ...
Jun  9 15:48:55 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:48:55 me20 kernel: at24 2-0050: write 32 at 8128 --> -121 (753883)
Jun  9 15:48:55 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:55 me20 kernel: at24 2-0050: write 32 at 8128 --> 0 (753884)
Jun  9 15:48:55 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: received nack
Jun  9 15:48:55 me20 kernel: at24 2-0050: write 32 at 8160 --> -121 (753884)
Jun  9 15:48:55 me20 kernel: i2c i2c-2: at91_xfer: processing 1 messages:
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: transfer: write 34 bytes.
Jun  9 15:48:55 me20 kernel: at91_i2c f801c000.i2c: transfer complete
Jun  9 15:48:55 me20 kernel: at24 2-0050: write 32 at 8160 --> 0 (753885)

Cheers,
Peter