[PATCH v2 3/3] i2c: stm32: only send a STOP upon transfer completion
Patrick DELAUNAY
patrick.delaunay at foss.st.com
Fri Sep 9 14:53:23 CEST 2022
Hi Alain
On 9/8/22 12:59, Alain Volmat wrote:
> Current function stm32_i2c_message_xfer is sending a STOP
> whatever the result of the transaction is. This can cause issues
> such as making the bus busy since the controller itself is already
> sending automatically a STOP when a NACK is generated. This can
> be especially seen when the processing get slower (ex: enabling lots
> of debug messages), ending up send 2 STOP (one automatically by the
> controller and a 2nd one at the end of the stm32_i2c_message_xfer
> function).
>
> Thanks to Jorge Ramirez-Ortiz for diagnosing and proposing a first
> fix for this. [1]
>
> [1] https://lore.kernel.org/u-boot/20220815145211.31342-2-jorge@foundries.io/
>
> Reported-by: Jorge Ramirez-Ortiz, Foundries <jorge at foundries.io>
> Signed-off-by: Jorge Ramirez-Ortiz <jorge at foundries.io>
> Signed-off-by: Alain Volmat <alain.volmat at foss.st.com>
> ---
> drivers/i2c/stm32f7_i2c.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/stm32f7_i2c.c b/drivers/i2c/stm32f7_i2c.c
> index 0ec67b5c12..8803979d3e 100644
> --- a/drivers/i2c/stm32f7_i2c.c
> +++ b/drivers/i2c/stm32f7_i2c.c
> @@ -477,16 +477,16 @@ static int stm32_i2c_message_xfer(struct stm32_i2c_priv *i2c_priv,
> if (ret)
> break;
>
> + /* End of transfer, send stop condition */
> + mask = STM32_I2C_CR2_STOP;
> + setbits_le32(®s->cr2, mask);
> +
> if (!stop)
> /* Message sent, new message has to be sent */
> return 0;
> }
> }
>
> - /* End of transfer, send stop condition */
> - mask = STM32_I2C_CR2_STOP;
> - setbits_le32(®s->cr2, mask);
> -
> return stm32_i2c_check_end_of_message(i2c_priv);
> }
>
Boot on DK2 failed with the traces:
U-Boot 2022.10-rc4-00043-g5b118161055 (Sep 09 2022 - 14:19:12 +0200)
CPU: STM32MP157CAC Rev.B
Model: STMicroelectronics STM32MP157C-DK2 Discovery Board
Board: stm32mp1 in trusted mode (st,stm32mp157c-dk2)
Board: MB1272 Var2.0 Rev.C-01
DRAM: 512 MiB
Clocks:
- MPU : 650 MHz
- MCU : 208.878 MHz
- AXI : 266.500 MHz
- PER : 24 MHz
- DDR : 533 MHz
stpmic1_pmic stpmic at 33: stpmic1_read: failed to read register 0x25 :
-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x25
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x25
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x2a
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x26
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x21
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x22
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x23
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x25
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x26
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write register 0x29
:-16stpmic1_pmic stpmic at 33: stpmic1_write: failed to write regi�Core:
275 devices, 40 uclasses, devicetree: board
WDT: Started watchdog at 5a002000 with servicing (32s timeout)
NAND: 0 MiB
MMC: STM32 SD/MMC: 0
Loading Environment from MMC... OK
In: serial
Out: serial
Err: serial
Net: eth0: ethernet at 5800a000
Hit any key to stop autoboot: 0
I think the code should be inserted AFTER the test "if (!stop)"
I modify the patch with
-------------------------- drivers/i2c/stm32f7_i2c.c
-------------------------- index aac592860e1..cd3bcdf8d99 100644 @@
-477,13 +477,12 @@ static int stm32_i2c_message_xfer(struct
stm32_i2c_priv *i2c_priv, if (ret) break; -/* End of transfer, send stop
condition */ -mask = STM32_I2C_CR2_STOP; -setbits_le32(®s->cr2,
mask); - if (!stop) /* Message sent, new message has to be sent */
return 0; + +/* End of transfer, send stop condition */
+setbits_le32(®s->cr2, STM32_I2C_CR2_STOP); } }
And the boot is OK, I2C read/tested is OK
test with the 2 available device on the board = STPMIC1 & STUSB1600
STM32MP> i2c bus
Bus 4: i2c at 40012000
Bus 3: i2c at 5c002000 (active 3)
28: stusb1600 at 28, offset len 1, flags 0
33: stpmic at 33, offset len 1, flags 0
STM32MP> pmic dev stpmic at 33
STM32MP> pmic dump
Dump pmic: stpmic at 33 registers
0x00: 00 10 00 00 00 01 10 00 00 00 00 00 00 00 00 00
0x10: 04 00 00 00 00 00 80 00 00 00 00 00 00 00 00 00
0x20: 61 79 d9 d9 01 25 61 7d 00 51 0d 00 00 00 00 00
0x30: 61 50 d9 d9 00 24 24 24 01 51 04 00 00 00 00 00
0x40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x80: ff ff ff cf 00 00 00 00 00 00 00 00 00 00 00 00
0x90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0xa0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0xb0: 00 00 00 00 00 00 00 00 08 00 00 00 00 00 01 02
0xc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0xd0: 00 00 00 00 00 00 00 00 00 00 0c 00 00 00 00 00
0xe0: aa 55 01 19 f0 81 84 00 31 03 0b 00 00 00 01 08
0xf0: 40 10 00 00 20 52 fd 0e ee 92 c0 02 f2 80 02 33
STM32MP> regulator status -a
Name Enabled uV mA Mode
reg11 disabled 1100000 - -
reg18 disabled 1800000 - -
usb33 disabled 3300000 - -
vrefbuf at 50025000 enabled 2500000 - -
vddcore enabled 1200000 - HP
vdd_ddr enabled 1350000 - HP
vdd enabled 3300000 - HP
v3v3 enabled 3300000 - HP
v1v8_audio enabled 1800000 - -
v3v3_hdmi enabled 3300000 - -
vtt_ddr enabled 675000 - SINK SOURCE
vdd_usb disabled 3300000 - -
vdda enabled 2900000 - -
v1v2_hdmi enabled 1200000 - -
vref_ddr enabled 675000 - -
bst_out disabled - - -
vbus_otg disabled - - -
vbus_sw disabled - - -
vin enabled 5000000 -
I2C write is OK: tested with :
STM32MP> regulator dev vbus_otg
dev: vbus_otg @ pwr_sw1
STM32MP> regulator enable
+ USB cable deconnection detection in 'ums command'
So I think you need to modify the patch
regards
Patrick
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