* [PATCH v3] i2c: designware: fix idx_write_cnt in read loop
@ 2023-05-24 18:14 David Zheng
2023-05-26 13:58 ` Jarkko Nikula
0 siblings, 1 reply; 5+ messages in thread
From: David Zheng @ 2023-05-24 18:14 UTC (permalink / raw)
To: linux-i2c, linux-kernel
Cc: jarkko.nikula, andriy.shevchenko, mika.westerberg, jsd
With IC_INTR_RX_FULL slave interrupt handler reads data in a loop until
RX FIFO is empty. When testing with the slave-eeprom, each transaction
has 2 bytes for address/index and 1 byte for value, the address byte
can be written as data byte due to dropping STOP condition.
In the test below, the master continuously writes to the slave, first 2
bytes are index, 3rd byte is value and follow by a STOP condition.
i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D1-D1]
i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D2-D2]
i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D3-D3]
Upon receiving STOP condition slave eeprom would reset `idx_write_cnt` so
next 2 bytes can be treated as buffer index for upcoming transaction.
Supposedly the slave eeprom buffer would be written as
EEPROM[0x00D1] = 0xD1
EEPROM[0x00D2] = 0xD2
EEPROM[0x00D3] = 0xD3
When CPU load is high the slave irq handler may not read fast enough,
the interrupt status can be seen as 0x204 with both DW_IC_INTR_STOP_DET
(0x200) and DW_IC_INTR_RX_FULL (0x4) bits. The slave device may see
the transactions below.
0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1794 : INTR_STAT=0x204
0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x1790 : INTR_STAT=0x200
0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
After `D1` is received, read loop continues to read `00` which is the
first bype of next index. Since STOP condition is ignored by the loop,
eeprom buffer index increased to `D2` and `00` is written as value.
So the slave eeprom buffer becomes
EEPROM[0x00D1] = 0xD1
EEPROM[0x00D2] = 0x00
EEPROM[0x00D3] = 0xD3
The fix is to use `FIRST_DATA_BYTE` (bit 11) in `IC_DATA_CMD` to split
the transactions. The first index byte in this case would have bit 11
set. Check this indication to inject I2C_SLAVE_WRITE_REQUESTED event
which will reset `idx_write_cnt` in slave eeprom.
Signed-off-by: David Zheng <david.zheng@intel.com>
---
Changes in v2:
- Send I2C_SLAVE_WRITE_REQUESTED for HW does not have FIRST_DATA_BYTE
Changes in v3:
- Move DW_IC_DATA_CMD_FIRST_DATA_BYTE next to DW_IC_DATA_CMD_DAT define
---
drivers/i2c/busses/i2c-designware-core.h | 1 +
drivers/i2c/busses/i2c-designware-slave.c | 4 ++++
2 files changed, 5 insertions(+)
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index c5d87aae39c6..bf23bfb51aea 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -40,6 +40,7 @@
#define DW_IC_CON_BUS_CLEAR_CTRL BIT(11)
#define DW_IC_DATA_CMD_DAT GENMASK(7, 0)
+#define DW_IC_DATA_CMD_FIRST_DATA_BYTE BIT(11)
/*
* Registers offset
diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
index cec25054bb24..2e079cf20bb5 100644
--- a/drivers/i2c/busses/i2c-designware-slave.c
+++ b/drivers/i2c/busses/i2c-designware-slave.c
@@ -176,6 +176,10 @@ static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
do {
regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
+ if (tmp & DW_IC_DATA_CMD_FIRST_DATA_BYTE)
+ i2c_slave_event(dev->slave,
+ I2C_SLAVE_WRITE_REQUESTED,
+ &val);
val = tmp;
i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
&val);
--
2.40.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v3] i2c: designware: fix idx_write_cnt in read loop
2023-05-24 18:14 [PATCH v3] i2c: designware: fix idx_write_cnt in read loop David Zheng
@ 2023-05-26 13:58 ` Jarkko Nikula
2023-06-05 10:02 ` Wolfram Sang
0 siblings, 1 reply; 5+ messages in thread
From: Jarkko Nikula @ 2023-05-26 13:58 UTC (permalink / raw)
To: David Zheng, linux-i2c, linux-kernel
Cc: andriy.shevchenko, mika.westerberg, jsd
On 5/24/23 21:14, David Zheng wrote:
> With IC_INTR_RX_FULL slave interrupt handler reads data in a loop until
> RX FIFO is empty. When testing with the slave-eeprom, each transaction
> has 2 bytes for address/index and 1 byte for value, the address byte
> can be written as data byte due to dropping STOP condition.
>
> In the test below, the master continuously writes to the slave, first 2
> bytes are index, 3rd byte is value and follow by a STOP condition.
>
> i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D1-D1]
> i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D2-D2]
> i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D3-D3]
>
> Upon receiving STOP condition slave eeprom would reset `idx_write_cnt` so
> next 2 bytes can be treated as buffer index for upcoming transaction.
> Supposedly the slave eeprom buffer would be written as
>
> EEPROM[0x00D1] = 0xD1
> EEPROM[0x00D2] = 0xD2
> EEPROM[0x00D3] = 0xD3
>
> When CPU load is high the slave irq handler may not read fast enough,
> the interrupt status can be seen as 0x204 with both DW_IC_INTR_STOP_DET
> (0x200) and DW_IC_INTR_RX_FULL (0x4) bits. The slave device may see
> the transactions below.
>
> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1794 : INTR_STAT=0x204
> 0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x1790 : INTR_STAT=0x200
> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
>
> After `D1` is received, read loop continues to read `00` which is the
> first bype of next index. Since STOP condition is ignored by the loop,
> eeprom buffer index increased to `D2` and `00` is written as value.
>
> So the slave eeprom buffer becomes
>
> EEPROM[0x00D1] = 0xD1
> EEPROM[0x00D2] = 0x00
> EEPROM[0x00D3] = 0xD3
>
> The fix is to use `FIRST_DATA_BYTE` (bit 11) in `IC_DATA_CMD` to split
> the transactions. The first index byte in this case would have bit 11
> set. Check this indication to inject I2C_SLAVE_WRITE_REQUESTED event
> which will reset `idx_write_cnt` in slave eeprom.
>
> Signed-off-by: David Zheng <david.zheng@intel.com>
> ---
> Changes in v2:
> - Send I2C_SLAVE_WRITE_REQUESTED for HW does not have FIRST_DATA_BYTE
> Changes in v3:
> - Move DW_IC_DATA_CMD_FIRST_DATA_BYTE next to DW_IC_DATA_CMD_DAT define
> ---
> drivers/i2c/busses/i2c-designware-core.h | 1 +
> drivers/i2c/busses/i2c-designware-slave.c | 4 ++++
> 2 files changed, 5 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
> index c5d87aae39c6..bf23bfb51aea 100644
> --- a/drivers/i2c/busses/i2c-designware-core.h
> +++ b/drivers/i2c/busses/i2c-designware-core.h
> @@ -40,6 +40,7 @@
> #define DW_IC_CON_BUS_CLEAR_CTRL BIT(11)
>
> #define DW_IC_DATA_CMD_DAT GENMASK(7, 0)
> +#define DW_IC_DATA_CMD_FIRST_DATA_BYTE BIT(11)
>
> /*
> * Registers offset
> diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
> index cec25054bb24..2e079cf20bb5 100644
> --- a/drivers/i2c/busses/i2c-designware-slave.c
> +++ b/drivers/i2c/busses/i2c-designware-slave.c
> @@ -176,6 +176,10 @@ static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
>
> do {
> regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
> + if (tmp & DW_IC_DATA_CMD_FIRST_DATA_BYTE)
> + i2c_slave_event(dev->slave,
> + I2C_SLAVE_WRITE_REQUESTED,
> + &val);
> val = tmp;
> i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
> &val);
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v3] i2c: designware: fix idx_write_cnt in read loop
2023-05-26 13:58 ` Jarkko Nikula
@ 2023-06-05 10:02 ` Wolfram Sang
2023-06-05 10:48 ` Jarkko Nikula
0 siblings, 1 reply; 5+ messages in thread
From: Wolfram Sang @ 2023-06-05 10:02 UTC (permalink / raw)
To: Jarkko Nikula
Cc: David Zheng, linux-i2c, linux-kernel, andriy.shevchenko,
mika.westerberg, jsd
[-- Attachment #1: Type: text/plain, Size: 2708 bytes --]
On Fri, May 26, 2023 at 04:58:26PM +0300, Jarkko Nikula wrote:
> On 5/24/23 21:14, David Zheng wrote:
> > With IC_INTR_RX_FULL slave interrupt handler reads data in a loop until
> > RX FIFO is empty. When testing with the slave-eeprom, each transaction
> > has 2 bytes for address/index and 1 byte for value, the address byte
> > can be written as data byte due to dropping STOP condition.
> >
> > In the test below, the master continuously writes to the slave, first 2
> > bytes are index, 3rd byte is value and follow by a STOP condition.
> >
> > i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D1-D1]
> > i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D2-D2]
> > i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D3-D3]
> >
> > Upon receiving STOP condition slave eeprom would reset `idx_write_cnt` so
> > next 2 bytes can be treated as buffer index for upcoming transaction.
> > Supposedly the slave eeprom buffer would be written as
> >
> > EEPROM[0x00D1] = 0xD1
> > EEPROM[0x00D2] = 0xD2
> > EEPROM[0x00D3] = 0xD3
> >
> > When CPU load is high the slave irq handler may not read fast enough,
> > the interrupt status can be seen as 0x204 with both DW_IC_INTR_STOP_DET
> > (0x200) and DW_IC_INTR_RX_FULL (0x4) bits. The slave device may see
> > the transactions below.
> >
> > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1794 : INTR_STAT=0x204
> > 0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x1790 : INTR_STAT=0x200
> > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> > 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
> >
> > After `D1` is received, read loop continues to read `00` which is the
> > first bype of next index. Since STOP condition is ignored by the loop,
> > eeprom buffer index increased to `D2` and `00` is written as value.
> >
> > So the slave eeprom buffer becomes
> >
> > EEPROM[0x00D1] = 0xD1
> > EEPROM[0x00D2] = 0x00
> > EEPROM[0x00D3] = 0xD3
> >
> > The fix is to use `FIRST_DATA_BYTE` (bit 11) in `IC_DATA_CMD` to split
> > the transactions. The first index byte in this case would have bit 11
> > set. Check this indication to inject I2C_SLAVE_WRITE_REQUESTED event
> > which will reset `idx_write_cnt` in slave eeprom.
> >
> > Signed-off-by: David Zheng <david.zheng@intel.com>
Applied to for-current, thanks!
Someone maybe has a Fixes tag for it?
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v3] i2c: designware: fix idx_write_cnt in read loop
2023-06-05 10:02 ` Wolfram Sang
@ 2023-06-05 10:48 ` Jarkko Nikula
2023-06-05 12:36 ` Wolfram Sang
0 siblings, 1 reply; 5+ messages in thread
From: Jarkko Nikula @ 2023-06-05 10:48 UTC (permalink / raw)
To: Wolfram Sang, David Zheng, linux-i2c, linux-kernel,
andriy.shevchenko, mika.westerberg, jsd
On 6/5/23 13:02, Wolfram Sang wrote:
> On Fri, May 26, 2023 at 04:58:26PM +0300, Jarkko Nikula wrote:
>> On 5/24/23 21:14, David Zheng wrote:
>>> With IC_INTR_RX_FULL slave interrupt handler reads data in a loop until
>>> RX FIFO is empty. When testing with the slave-eeprom, each transaction
>>> has 2 bytes for address/index and 1 byte for value, the address byte
>>> can be written as data byte due to dropping STOP condition.
>>>
>>> In the test below, the master continuously writes to the slave, first 2
>>> bytes are index, 3rd byte is value and follow by a STOP condition.
>>>
>>> i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D1-D1]
>>> i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D2-D2]
>>> i2c_write: i2c-3 #0 a=04b f=0000 l=3 [00-D3-D3]
>>>
>>> Upon receiving STOP condition slave eeprom would reset `idx_write_cnt` so
>>> next 2 bytes can be treated as buffer index for upcoming transaction.
>>> Supposedly the slave eeprom buffer would be written as
>>>
>>> EEPROM[0x00D1] = 0xD1
>>> EEPROM[0x00D2] = 0xD2
>>> EEPROM[0x00D3] = 0xD3
>>>
>>> When CPU load is high the slave irq handler may not read fast enough,
>>> the interrupt status can be seen as 0x204 with both DW_IC_INTR_STOP_DET
>>> (0x200) and DW_IC_INTR_RX_FULL (0x4) bits. The slave device may see
>>> the transactions below.
>>>
>>> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
>>> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
>>> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
>>> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1794 : INTR_STAT=0x204
>>> 0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x1790 : INTR_STAT=0x200
>>> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
>>> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
>>> 0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x1594 : INTR_STAT=0x4
>>>
>>> After `D1` is received, read loop continues to read `00` which is the
>>> first bype of next index. Since STOP condition is ignored by the loop,
>>> eeprom buffer index increased to `D2` and `00` is written as value.
>>>
>>> So the slave eeprom buffer becomes
>>>
>>> EEPROM[0x00D1] = 0xD1
>>> EEPROM[0x00D2] = 0x00
>>> EEPROM[0x00D3] = 0xD3
>>>
>>> The fix is to use `FIRST_DATA_BYTE` (bit 11) in `IC_DATA_CMD` to split
>>> the transactions. The first index byte in this case would have bit 11
>>> set. Check this indication to inject I2C_SLAVE_WRITE_REQUESTED event
>>> which will reset `idx_write_cnt` in slave eeprom.
>>>
>>> Signed-off-by: David Zheng <david.zheng@intel.com>
>
> Applied to for-current, thanks!
>
> Someone maybe has a Fixes tag for it?
>
In my opinion this patch is more improvement rather than a regression fix.
I see it's continuation to the commits dcf1bf648f94 ("i2c: designware:
Empty receive FIFO in slave interrupt handler") and 3b5f7f10ff6e ("i2c:
designware: slave should do WRITE_REQUESTED before WRITE_RECEIVED").
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v3] i2c: designware: fix idx_write_cnt in read loop
2023-06-05 10:48 ` Jarkko Nikula
@ 2023-06-05 12:36 ` Wolfram Sang
0 siblings, 0 replies; 5+ messages in thread
From: Wolfram Sang @ 2023-06-05 12:36 UTC (permalink / raw)
To: Jarkko Nikula
Cc: David Zheng, linux-i2c, linux-kernel, andriy.shevchenko,
mika.westerberg, jsd
[-- Attachment #1: Type: text/plain, Size: 100 bytes --]
> In my opinion this patch is more improvement rather than a regression fix.
Okay, then, thanks!
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2023-05-24 18:14 [PATCH v3] i2c: designware: fix idx_write_cnt in read loop David Zheng
2023-05-26 13:58 ` Jarkko Nikula
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2023-06-05 10:48 ` Jarkko Nikula
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