Re: [PATCH v19 2/7] firmware: arm_rmm: Check for RMI support at init

[Suzuki K Poulose]

On 25/09/2026 01:00, Gavin Shan wrote:
> On 9/24/26 11:51 PM, Suzuki K Poulose wrote:
> > From: Steven Price <steven.price@xxxxxxx>
> >
> > Query the RMI version number and check if it is a compatible version.
> > The first two feature registers are read and exposed for future code to
> > use.
> >
> > We only support this for Little Endian kernels, the Big Endian kernel
> > support is anyway marked BROKEN and is being removed.
> >
> > Signed-off-by: Steven Price <steven.price@xxxxxxx>
> > Co-developed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > ---
> > v19:
> >   * Read all implemented RmiFeatureRegisters - 5
> >   * Use ARRAY_SIZE(rmi_feat_reg_cache) for the loop in 
> > rmi_read_features()
> >   * Fold rmi_features() into rmi_read_features
> >   * Fix comment for rmi_smccc_invoke()
> >   * Drop default y
> >   * Add retry for RMI_BLOCKED and return to caller
> > v18:
> >   * Always use arm_smccc_1_2_invoke() for all RMIs making sure the 
> > unsused
> >     parameters are 0 - Sashiko
> >   * Move rmi_features() calls away from the arm-rmi-cmds.h to rmi.c - 
> > Gavin
> > v17:
> >   * Rename ARM_RMM to ARM_RMM_RMI to make it easier to add Guest 
> > facing RSI
> >     support, which is also in progress
> > v16:
> >   * Update Kconfig text to include PCIe TDISP.
> >   * Export rmi_feat_reg() here rather than in a later commit.
> > v15:
> >   * The code is moved again, this time into the 'firmware' directory.
> > v14:
> >   * This moves the basic RMI setup into the 'kernel' directory. This is
> >     because RMI will be used for some features outside of KVM so should
> >     be available even if KVM isn't compiled in.
> > ---
> >   arch/arm64/Kconfig                |   1 +
> >   arch/arm64/kernel/cpufeature.c    |   1 +
> >   drivers/firmware/Kconfig          |   1 +
> >   drivers/firmware/Makefile         |   1 +
> >   drivers/firmware/arm_rmm/Kconfig  |  25 +++++++
> >   drivers/firmware/arm_rmm/Makefile |   2 +
> >   drivers/firmware/arm_rmm/rmi.c    | 109 ++++++++++++++++++++++++++++++
> >   include/linux/arm-rmi-cmds.h      |  48 +++++++++++++
> >   8 files changed, 188 insertions(+)
> >   create mode 100644 drivers/firmware/arm_rmm/Kconfig
> >   create mode 100644 drivers/firmware/arm_rmm/Makefile
> >   create mode 100644 drivers/firmware/arm_rmm/rmi.c
> >   create mode 100644 include/linux/arm-rmi-cmds.h
>
> Some nitpicks below, with them addressed:
>
> Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>

Thank you Gavin, much appreciated ! I have addressed the comments below
and the Makefile one.

Cheers
Suzuki