Re: [PATCH v4 0/3] drm/xe/i2c: alerts and controller enabling modifications

[Rodrigo Vivi]

On Mon, Jul 13, 2026 at 05:55:58PM +0200, Heikki Krogerus wrote:
> Hi,
> 
> The hardware challenges that these patches address are so severe that I'm
> marking both of them as fixes. In both cases the GPU may silently end up in
> unresponsive state (or worse). The second patch has been refactored so that it
> includes the direct AMC alert handling in Xe instead of the normal alert handler
> registration. The subject lines were also changed to highlight the fact that
> these are fixes. Ramesh helped me with the testing and with the implementation
> for the AMC alert handling.
> 
> Changed since v2:
> - Added Fixes tag to both patches.
> - i2c-designware is no longer supplied with an interrupt so it will be in
>   polling mode (ACCESS_POLLING will be enabled). The IRQ path in hardware can't
>   handle the amount of interrupts the i2c controller generates. Only the
>   interrupts from the SMBus Alert line are left enabled.
> - The registration of the default smbus alert handler is dropped.
> - The AMC alerts are handled directly in Xe. All the alerts will cause the
>   device to be declared as wedged at least for now.
> - Cleanups proposed by Raag.
> 
> v2: https://lore.kernel.org/lkml/20260625125939.429078-1-heikki.krogerus@xxxxxxxxxxxxxxx/
> 
> Changed since v1:
> - Global header for the DesignWare I2C registers which meant a bit of
>   patch refactoring.
> - Selecting CONFIG_SMBUS in CONFIG_XE and handling smbus in xe_i2c.c instead of
>   separate file.
> - Storing the alert device to the client array and providing enum for the
>   clients.
> - Allowing other fields in the IC_ENABLE register to be updated except the
>   Enable bit.
> - Can't sleep in xe_i2c_disable() so using udelay().
> 
> v1: https://lore.kernel.org/lkml/20260622114759.3464047-1-heikki.krogerus@xxxxxxxxxxxxxxx/
> 
> This includes support for the SMBus alerts, and special handling for the
> IC_ENABLE register.
> 
> Thanks,


Please take a look to Shashiko review and let us know in case of false positives:
https://sashiko.dev/#/patchset/20260713155601.711389-1-heikki.krogerus%40linux.intel.com

> 
> Heikki Krogerus (3):
>   i2c: designware: Global register definitions
>   drm/xe/i2c: Fix the interrupt handling
>   drm/xe/i2c: Keep the i2c controller always enabled
> 
>  MAINTAINERS                                |   1 +
>  drivers/gpu/drm/xe/Makefile                |   4 +-
>  drivers/gpu/drm/xe/regs/xe_i2c_regs.h      |   2 +
>  drivers/gpu/drm/xe/xe_amc.c                | 173 +++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_amc.h                |  25 +++
>  drivers/gpu/drm/xe/xe_i2c.c                | 136 +++++++++-------
>  drivers/gpu/drm/xe/xe_i2c.h                |  14 +-
>  drivers/i2c/busses/i2c-designware-common.c |   2 +
>  drivers/i2c/busses/i2c-designware-core.h   |  85 +---------
>  drivers/i2c/busses/i2c-designware-master.c |   2 +
>  drivers/i2c/busses/i2c-designware-slave.c  |   2 +
>  include/linux/designware_i2c.h             | 107 +++++++++++++
>  12 files changed, 405 insertions(+), 148 deletions(-)
>  create mode 100644 drivers/gpu/drm/xe/xe_amc.c
>  create mode 100644 drivers/gpu/drm/xe/xe_amc.h
>  create mode 100644 include/linux/designware_i2c.h
> 
> -- 
> 2.50.1
>