Re: [PATCH v10 0/9] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

Josua Mayer
2026-02-25T12:14:39Z

Am 25.02.26 um 12:34 schrieb Josua Mayer:
> This series has evolved over time from adding generic mux support for
> renesas sdhi driver, to partial rewrite of the mux framework.
>
> Several drivers have started implementing driver-local managed and
> unmanaged helper functions for getting and selecting a mux-state object.
>
> mmc maintainers have requested that new code shall intreoduce and use
> generic helper functions that can be shared by all drivers, avoiding
> code duplication.
>
> This series is structured in 5 parts, each of which is self-sufficient
> depending only on the previous patches. This shall allow the first N
> patches to be applied even if the last ones need further discussion.
>
> 1. Rename driver-local helper functions to avoid name collision with
> global version to be introduced later.
>
> 2. Implement generic device-managed helper functions in mux core.
>
> 3. Convert driver local code from similar patterns to use the newly
> added global helpers.
>
> 4. Change mux-core Kconfig so that it can be enabled through menuconfig,
> without an explicit "select" dependency from other drivers.
>
> 5. add dt bindings and driver support for mux in renesas sdhi driver.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>
> ---
> Changes in v10:
> - added renesas-sdhi Kconfig dependency for MULTIPLEXER, avoiding build
> errors in case setting SDHI=y and MULTIPLEXER=m is attempted.
> Trailers were dropped on this patch to encourage fresh review.
> - renamed phy-can-transceiver driver-local helper function to be
> consistent with other driver-local functions, and dropped all trailers
> for this particular patch.
> - reconsidered the Kconfig changes due to inputs from mux core author
> - handle newly-added mux usage in rcar-gen3-usb2 introduced with
> v7.0-rc1
> - streamline patch sequence
> - rebase on v7.0-rc1
> - Link to v9: https://lore.kernel.org/r/20260208-rz-sdio-mux-v9-0-9a3be13c1280@solid-run.com
>
> Changes in v9:
> - compile-tested on x86 with MULTIPLEXER=m/y/unset.
> - fixed Kconfig changes so that CONFIG_MULTIPLEXER can be selected.
> through menuconfig / .config as intended.
> - updated trailers
> - document null return value for mux_control_get_optional.
> - fix build error for CONFIG_MULTIPLEXER=m, found with x86_64
> allmodconfig: replaced ifdef ... with if IS_ENABLED(...).
> (Reported-by: Mark Brown <broonie@kernel.org>)
> - Link to v8: https://lore.kernel.org/r/20260203-rz-sdio-mux-v8-0-024ea405863e@solid-run.com
>
> 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@solid-run.com
>
> 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@linux-m68k.org>)
> - 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@solid-run.com
>
> 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@intel.com>)
> - Link to v5: https://lore.kernel.org/r/20260118-rz-sdio-mux-v5-0-3c37e8872683@solid-run.com
>
> Changes in v5:
> - implemented automatic mux deselect for devm_*_selected.
> (Reported-by: Wolfram Sang <wsa+renesas@sang-engineering.com>)
> - 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@intel.com>)
> - Link to v4: https://lore.kernel.org/r/20251229-rz-sdio-mux-v4-0-a023e55758fe@solid-run.com
>
> 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@linux-m68k.org>)
> - refactored mux core logic to silence ENOENT errors only on optional
> code paths, keeping error printing unchanged otherwise.
> (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
> - picked up various reviewed- and acked-by tags
> - Link to v3: https://lore.kernel.org/r/20251210-rz-sdio-mux-v3-0-ca628db56d60@solid-run.com
>
> 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@kernel.org>)
> - 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@linaro.org>)
> - Link to v2: https://lore.kernel.org/r/20251201-rz-sdio-mux-v2-0-bcb581b88dd7@solid-run.com
>
> Changes in v2:
> - dropped mux-controller node from dt binding example
> (Reported-by: Conor Dooley <conor@kernel.org>
> Reported-by: Krzysztof Kozlowski <krzk@kernel.org>)
> - Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com
>
> ---
> Josua Mayer (9):
> phy: can-transceiver: rename temporary helper function to avoid conflict
> phy: renesas: rcar-gen3-usb2: rename local mux helper to avoid conflict
> mux: Add helper functions for getting optional and selected mux-state
Series may be split here, at this point the new helpers have zero users,
but names have been reserved, avoiding future driver-local name conflicts.

This is the most critical piece, it would be good if it can be applied to next early,
pending review and kernel robot results of course.

> phy: can-transceiver: drop temporary helper getting optional mux-state
> phy: renesas: rcar-gen3-usb2: drop helper getting optional mux-state
> i2c: omap: switch to new generic helper for getting selected mux-state
Series may be split here treating renesas-sdhi & mux Kconfig searate.
> dt-bindings: mmc: renesas,sdhi: Add mux-states property
> mux: add prompt and help text to CONFIG_MULTIPLEXER making it visible
> 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/Kconfig | 1 +
> drivers/mmc/host/renesas_sdhi_core.c | 6 +
> drivers/mux/Kconfig | 9 +-
> drivers/mux/core.c | 206 +++++++++++++++++----
> drivers/phy/phy-can-transceiver.c | 10 -
> drivers/phy/renesas/phy-rcar-gen3-usb2.c | 30 +--
> include/linux/mux/consumer.h | 108 ++++++++++-
> 9 files changed, 307 insertions(+), 93 deletions(-)
> ---
> base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
> change-id: 20251128-rz-sdio-mux-acc5137f1618
>
> Best regards,