Re: [PATCH 33/34] drivers: remove incorrect of_match_ptr/ACPI_PTR annotations

[Peter Rosin]

Hi!

2024-04-03 at 10:06, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> When building with CONFIG_OF and/or CONFIG_ACPI disabled but W=1 extra
> warnings enabled, a lot of driver cause a warning about an unused
> ID table:
> 
> drivers/char/tpm/tpm_ftpm_tee.c:356:34: error: unused variable 'of_ftpm_tee_ids' [-Werror,-Wunused-const-variable]
> drivers/dma/img-mdc-dma.c:863:34: error: unused variable 'mdc_dma_of_match' [-Werror,-Wunused-const-variable]
> drivers/fpga/versal-fpga.c:62:34: error: unused variable 'versal_fpga_of_match' [-Werror,-Wunused-const-variable]
> drivers/i2c/muxes/i2c-mux-ltc4306.c:200:34: error: unused variable 'ltc4306_of_match' [-Werror,-Wunused-const-variable]
> drivers/i2c/muxes/i2c-mux-reg.c:242:34: error: unused variable 'i2c_mux_reg_of_match' [-Werror,-Wunused-const-variable]
> drivers/memory/pl353-smc.c:62:34: error: unused variable 'pl353_smc_supported_children' [-Werror,-Wunused-const-variable]
> drivers/regulator/pbias-regulator.c:136:34: error: unused variable 'pbias_of_match' [-Werror,-Wunused-const-variable]
> drivers/regulator/twl-regulator.c:552:34: error: unused variable 'twl_of_match' [-Werror,-Wunused-const-variable]
> drivers/regulator/twl6030-regulator.c:645:34: error: unused variable 'twl_of_match' [-Werror,-Wunused-const-variable]
> drivers/scsi/hisi_sas/hisi_sas_v2_hw.c:3635:36: error: unused variable 'sas_v2_acpi_match' [-Werror,-Wunused-const-variable]
> drivers/staging/pi433/pi433_if.c:1359:34: error: unused variable 'pi433_dt_ids' [-Werror,-Wunused-const-variable]
> drivers/tty/serial/amba-pl011.c:2945:34: error: unused variable 'sbsa_uart_of_match' [-Werror,-Wunused-const-variable]
> 
> The fix is always to just remove the of_match_ptr() and ACPI_PTR() wrappers
> that remove the reference, rather than adding another #ifdef just for build
> testing for a configuration that doesn't matter in practice.
> 
> I considered splitting up the large patch into per subsystem patches, but since
> it's really just the same thing everywhere it feels better to do it all at once.
> 
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  drivers/char/ipmi/ipmb_dev_int.c          | 2 +-
>  drivers/char/tpm/tpm_ftpm_tee.c           | 2 +-
>  drivers/dma/img-mdc-dma.c                 | 2 +-
>  drivers/fpga/versal-fpga.c                | 2 +-
>  drivers/hid/hid-google-hammer.c           | 6 ++----
>  drivers/i2c/muxes/i2c-mux-ltc4306.c       | 2 +-
>  drivers/i2c/muxes/i2c-mux-reg.c           | 2 +-
>  drivers/input/touchscreen/wdt87xx_i2c.c   | 2 +-
>  drivers/mux/adg792a.c                     | 2 +-
>  drivers/net/ethernet/apm/xgene-v2/main.c  | 2 +-
>  drivers/net/ethernet/hisilicon/hns_mdio.c | 2 +-
>  drivers/regulator/pbias-regulator.c       | 2 +-
>  drivers/regulator/twl-regulator.c         | 2 +-
>  drivers/regulator/twl6030-regulator.c     | 2 +-
>  drivers/rtc/rtc-fsl-ftm-alarm.c           | 2 +-
>  drivers/scsi/hisi_sas/hisi_sas_v1_hw.c    | 2 +-
>  drivers/scsi/hisi_sas/hisi_sas_v2_hw.c    | 2 +-
>  drivers/staging/pi433/pi433_if.c          | 2 +-
>  drivers/tty/serial/amba-pl011.c           | 6 +++---
>  drivers/tty/serial/ma35d1_serial.c        | 2 +-
>  20 files changed, 23 insertions(+), 25 deletions(-)

As far as I can tell, this triggers unconditional use of the
of_match_table, and the compiler will have a harder time dropping
that data. However, the wasted data is negligible for the parts
touching "my" drivers:

drivers/i2c/muxes/i2c-mux-ltc4306.c
drivers/i2c/muxes/i2c-mux-reg.c
drivers/mux/adg729a.c

Acked-by: Peter Rosin <peda@xxxxxxxxxx>

Cheers,
Peter