drivers/i2c/busses/i2c-designware-common.c | 6 + drivers/i2c/busses/i2c-designware-core.h | 3 + drivers/i2c/busses/i2c-designware-master.c | 197 ++++++++++++++++++++-------- drivers/i2c/busses/i2c-designware-platdrv.c | 5 +- 4 files changed, 153 insertions(+), 58 deletions(-)
Add support for the I2C_M_STOP flag to the .xfer() function of the
designware driver. This allows grouping multiple accesses in a single
call and changing the target address after a STOP flag. This is achieved
by splitting i2c_dw_xfer() in two functions. The core logic handling
the transaction is now in __i2c_dw_xfer_one_part(), while i2c_dw_xfer()
loops over the messages to search for the I2C_M_STOP flag and calls
__i2c_dw_xfer_one_part().
Handle controllers that lack the ability to emit a RESTART when two
consecutive messages have the same address and direction by aborting
transfers that contain such a sequence of messages. For those controllers,
we also check that we do not get any unwanted STOP caused by a Tx FIFO
underrun, as they lack the ability to hold the clock during a transaction.
And we set the irq as non-threaded to prevent underrun on PREEMPT-RT
kernel when filling the FIFO.
The I2C controllers found in the EyeQ6Lplus and EyeQ7H SoCs from Mobileye
lack such capability, so a compatible string is added because this cannot
be detected at runtime.
This patch series also brings four cleanups:
* Optimize the read of the message flags in i2c_dw_read().
* Sort the compatible strings alphabetically in dw_i2c_of_match[].
* Simplify runtime PM handling in i2c_dw_xfer() with guard.
* Add a dedicated i2c_algorithm for AMD NAVI controller.
Signed-off-by: Benoît Monin <benoit.monin@bootlin.com>
---
Changes in v5:
- Rebased on v6.19-rc6 and fully retested on EyeQ6Lplus.
- Drop dt-binding patch: already merged upstream in v6.19-rc2.
- From Andi Shyti's review:
- __i2c_dw_xfer_one_part() now returns 0 on success instead
of the number of messages transferred.
- Drop inline keyword from i2c_dw_msg_is_valid() declaration.
- Link to v4: https://lore.kernel.org/r/20251126-i2c-dw-v4-0-b0654598e7c5@bootlin.com
Changes in v4:
- Use a boolean property instead of a flag for handling controllers
IC_EMPTYFIFO_HOLD_MASTER_EN.
- Reorder the patches so goto and runtime PM auto-cleanup are not mixed
in i2c_dw_xfer().
- Drop goto in __i2c_dw_xfer_one_part() and use return.
- Tidy up comments for i2c_dw_msg_is_valid() and irq_flags.
- Link to v3: https://lore.kernel.org/r/20251119-i2c-dw-v3-0-bc4bc2a2cbac@bootlin.com
Changes in v3:
- Add a compatible entry for Mobileye EyeQ7H i2c controllers.
- Use runtime PM macro for auto-cleanup in i2c_dw_xfer().
- Add a dedicated i2c_algorithm for AMD NAVI controllers.
- Rename __i2c_dw_xfer_unlocked() as it is not about locking at all.
- Rework the validity check of i2c_msg.
- Flag the irq as non-threaded for controllers that cannot hold the
clock to avoid underrun.
- Link to v2: https://lore.kernel.org/r/20251031-i2c-dw-v2-0-90416874fcc0@bootlin.com
Changes in v2:
- Add a single compatible for mobileye i2c controllers based in
DesignWare IP.
- Handle the I2C_M_STOP flag instead of emitting a STOP on target address
change.
- Abort transfer when it requires a RESTART on controller that cannot
emit them.
- Detect FIFO underrun instead of disabling threaded interrupt on
PREEMPT_RT kernel.
- Sort the compatible entries in a separate patch.
- Add a cleanup patch on flag reading in i2c_dw_read().
- Link to v1: https://lore.kernel.org/r/20251017-i2c-dw-v1-0-7b85b71c7a87@bootlin.com
---
Benoît Monin (6):
i2c: designware: Optimize flag reading in i2c_dw_read()
i2c: designware: Sort compatible strings in alphabetical order
i2c: designware: Add dedicated algorithm for AMD NAVI
i2c: designware: Implement I2C_M_STOP support
i2c: designware: Use runtime PM macro for auto-cleanup
i2c: designware: Support of controller with IC_EMPTYFIFO_HOLD_MASTER disabled
drivers/i2c/busses/i2c-designware-common.c | 6 +
drivers/i2c/busses/i2c-designware-core.h | 3 +
drivers/i2c/busses/i2c-designware-master.c | 197 ++++++++++++++++++++--------
drivers/i2c/busses/i2c-designware-platdrv.c | 5 +-
4 files changed, 153 insertions(+), 58 deletions(-)
---
base-commit: 24d479d26b25bce5faea3ddd9fa8f3a6c3129ea7
change-id: 20251014-i2c-dw-da315f758296
Best regards,
--
Benoît Monin, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
On Tue, Jan 20, 2026 at 10:28:00AM +0100, Benoît Monin wrote: > Add support for the I2C_M_STOP flag to the .xfer() function of the > designware driver. This allows grouping multiple accesses in a single > call and changing the target address after a STOP flag. This is achieved > by splitting i2c_dw_xfer() in two functions. The core logic handling > the transaction is now in __i2c_dw_xfer_one_part(), while i2c_dw_xfer() > loops over the messages to search for the I2C_M_STOP flag and calls > __i2c_dw_xfer_one_part(). > > Handle controllers that lack the ability to emit a RESTART when two > consecutive messages have the same address and direction by aborting > transfers that contain such a sequence of messages. For those controllers, > we also check that we do not get any unwanted STOP caused by a Tx FIFO > underrun, as they lack the ability to hold the clock during a transaction. > And we set the irq as non-threaded to prevent underrun on PREEMPT-RT > kernel when filling the FIFO. > > The I2C controllers found in the EyeQ6Lplus and EyeQ7H SoCs from Mobileye > lack such capability, so a compatible string is added because this cannot > be detected at runtime. > > This patch series also brings four cleanups: > * Optimize the read of the message flags in i2c_dw_read(). > * Sort the compatible strings alphabetically in dw_i2c_of_match[]. > * Simplify runtime PM handling in i2c_dw_xfer() with guard. > * Add a dedicated i2c_algorithm for AMD NAVI controller. > > Signed-off-by: Benoît Monin <benoit.monin@bootlin.com> > --- > Changes in v5: > - Rebased on v6.19-rc6 and fully retested on EyeQ6Lplus. > - Drop dt-binding patch: already merged upstream in v6.19-rc2. > - From Andi Shyti's review: > - __i2c_dw_xfer_one_part() now returns 0 on success instead > of the number of messages transferred. > - Drop inline keyword from i2c_dw_msg_is_valid() declaration. > - Link to v4: https://lore.kernel.org/r/20251126-i2c-dw-v4-0-b0654598e7c5@bootlin.com Why you dropped my ack?
On Tuesday, 20 January 2026 at 11:01:29 CET, Mika Westerberg wrote: > On Tue, Jan 20, 2026 at 10:28:00AM +0100, Benoît Monin wrote: [...] > > Changes in v5: > > - Rebased on v6.19-rc6 and fully retested on EyeQ6Lplus. > > - Drop dt-binding patch: already merged upstream in v6.19-rc2. > > - From Andi Shyti's review: > > - __i2c_dw_xfer_one_part() now returns 0 on success instead > > of the number of messages transferred. > > - Drop inline keyword from i2c_dw_msg_is_valid() declaration. > > - Link to v4: https://lore.kernel.org/r/20251126-i2c-dw-v4-0-b0654598e7c5@bootlin.com > > Why you dropped my ack? > Sorry about that! I somehow forgot about it and b4 did not catch it either. @Andi: Should I resend the series with Mika's acked-by or you handle it on your side? Thanks, -- Benoît Monin, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
Hi Benoit, On Tue, Jan 20, 2026 at 04:17:46PM +0100, Benoît Monin wrote: > On Tuesday, 20 January 2026 at 11:01:29 CET, Mika Westerberg wrote: > > On Tue, Jan 20, 2026 at 10:28:00AM +0100, Benoît Monin wrote: > [...] > > > Changes in v5: > > > - Rebased on v6.19-rc6 and fully retested on EyeQ6Lplus. > > > - Drop dt-binding patch: already merged upstream in v6.19-rc2. > > > - From Andi Shyti's review: > > > - __i2c_dw_xfer_one_part() now returns 0 on success instead > > > of the number of messages transferred. > > > - Drop inline keyword from i2c_dw_msg_is_valid() declaration. > > > - Link to v4: https://lore.kernel.org/r/20251126-i2c-dw-v4-0-b0654598e7c5@bootlin.com > > > > Why you dropped my ack? > > > Sorry about that! I somehow forgot about it and b4 did not catch it either. > > @Andi: Should I resend the series with Mika's acked-by or you handle it on > your side? The ones I have applied so far have Mika's ack. If I write: Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> b4 will take it automatically for all the remaining patches :-) No need to resend unless required by other reasons. Thanks, Andi
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