Re: [PATCH v8 0/7] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[Ulf Hansson]

On Wed, 4 Feb 2026 at 16:33, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>
> On Tue, 3 Feb 2026 at 14:01, Josua Mayer <josua@xxxxxxxxxxxxx> wrote:
> >
> > Some Renesas SoC based boards mux SD and eMMC on a single sdio
> > controller, exposing user control by dip switch and software control by
> > gpio.
> >
> > Purpose is to simplify development and provisioning by selecting boot
> > media at power-on, and again before starting linux.
> >
> > Add binding and driver support for linking a (gpio) mux to renesas sdio
> > controller.
> >
> > Introduce generic helper functions for getting managed and selected
> > mux-state objects, and switch i2c-omap and phy-can-transceiver drivers.
> >
> > Signed-off-by: Josua Mayer <josua@xxxxxxxxxxxxx>
> > ---
> > Changes in v8:
> > - Add defensive null checks for all non-optional calls to internal
> >   mux_get function.
> > - Document NULL return value on applicable functions.
> > - Avoid IS_ERR_OR_NULL and ERR_PTR(0) to disarm smatch errors.
> > - Link to v7: https://lore.kernel.org/r/20260128-rz-sdio-mux-v7-0-92ebb6da0df8@xxxxxxxxxxxxx
> >
> > Changes in v7:
> > - picked up reviewed-tags
> > - fix Kconfig change to add the missing prompt for CONFIG_MULTIPLEXER,
> >   and enable it by default when COMPILE_TEST is set.
> >   (Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>)
> > - fix another kernel build robot warning: undocumented C struct member
> > - Link to v6: https://lore.kernel.org/r/20260121-rz-sdio-mux-v6-0-38aa39527928@xxxxxxxxxxxxx
> >
> > Changes in v6:
> > - replaced /* with /** for devm_mux_state_state function description.
> > - collected review tags.
> > - fixed checkpatch warnings (space-before-tab, void-return).
> >   (Reported-by: Geert Uytterhoeven)
> > - fixed use-after-free in mux core mux_get function.
> >   (Reported-by: Geert Uytterhoeven)
> > - fix mux helper error path uninitialised return code variable.
> >   (Reported-by: kernel test robot <lkp@xxxxxxxxx>)
> > - Link to v5: https://lore.kernel.org/r/20260118-rz-sdio-mux-v5-0-3c37e8872683@xxxxxxxxxxxxx
> >
> > Changes in v5:
> > - implemented automatic mux deselect for devm_*_selected.
> >   (Reported-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>)
> > - because of semantic changes I dropped reviewed and acks from omap-i2c
> >   patch (Andreas Kemnade / Wolfram Sang).
> > - fix invalid return value in void function for mux helper stubs
> >   (Reported-by: kernel test robot <lkp@xxxxxxxxx>)
> > - Link to v4: https://lore.kernel.org/r/20251229-rz-sdio-mux-v4-0-a023e55758fe@xxxxxxxxxxxxx
> >
> > Changes in v4:
> > - added MULTIPLEXER Kconfig help text.
> > - removed "select MULTIPLEXER" from renesas sdhi Kconfig, as it is
> >   not required for all devices using this driver.
> > - added stubs for all symbols exported by mux core.
> >   (Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>)
> > - refactored mux core logic to silence ENOENT errors only on optional
> >   code paths, keeping error printing unchanged otherwise.
> >   (Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>)
> > - picked up various reviewed- and acked-by tags
> > - Link to v3: https://lore.kernel.org/r/20251210-rz-sdio-mux-v3-0-ca628db56d60@xxxxxxxxxxxxx
> >
> > Changes in v3:
> > - updated omap-i2c and phy-can-transceiver to use new helpers.
> > - created generic helper functions for getting managed optional mux-state.
> >   (Reported-by: Rob Herring <robh@xxxxxxxxxx>)
> > - picked up binding ack by Rob Herring.
> > - replaced use of "SDIO" with "SD/SDIO/eMMC" in binding document and
> >   commit descriptions.
> >   (Reported-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>)
> > - Link to v2: https://lore.kernel.org/r/20251201-rz-sdio-mux-v2-0-bcb581b88dd7@xxxxxxxxxxxxx
> >
> > Changes in v2:
> > - dropped mux-controller node from dt binding example
> >   (Reported-by: Conor Dooley <conor@xxxxxxxxxx>
> >    Reported-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>)
> > - Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@xxxxxxxxxxxxx
> >
> > ---
> > Josua Mayer (7):
> >       phy: can-transceiver: rename temporary helper function to avoid conflict
> >       mux: Add helper functions for getting optional and selected mux-state
> >       mux: add help text for MULTIPLEXER config option
> >       phy: can-transceiver: drop temporary helper getting optional mux-state
> >       i2c: omap: switch to new generic helper for getting selected mux-state
> >       dt-bindings: mmc: renesas,sdhi: Add mux-states property
> >       mmc: host: renesas_sdhi_core: support selecting an optional mux
> >
> >  .../devicetree/bindings/mmc/renesas,sdhi.yaml      |   6 +
> >  drivers/i2c/busses/i2c-omap.c                      |  24 +--
> >  drivers/mmc/host/renesas_sdhi_core.c               |   6 +
> >  drivers/mux/Kconfig                                |   8 +-
> >  drivers/mux/core.c                                 | 205 +++++++++++++++++----
> >  drivers/phy/phy-can-transceiver.c                  |  10 -
> >  include/linux/mux/consumer.h                       | 108 ++++++++++-
> >  7 files changed, 302 insertions(+), 65 deletions(-)
> > ---
> > base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
> > change-id: 20251128-rz-sdio-mux-acc5137f1618
> >
> > Best regards,
> > --
> > Josua Mayer <josua@xxxxxxxxxxxxx>
> >
> >
>
> The series applied for next, thanks!

Unfortunately my pull request for MMC for v7.0 was broken and will not
be pulled by Linus, hence I need to drop the $subject series from my
next branch.

Please submit a new version of the series when v7.0-rc1 is out and
let's fix the build errors and the dependency to the phy subsystem [1]
properly, so we can land this for v7.1 instead.

Kind regards
Uffe

[1]
https://lkml.org/lkml/2026/2/12/399 (lore was down, so pointing to
lkml.org instead)