[PATCH v3 00/20] BYEWORD_UPDATE: unifying (most) HIWORD_UPDATE macros

Nicolas Frattaroli
2025-08-25T08:30:12Z

This series was spawned by [1], where I was asked to move every instance
of HIWORD_UPDATE et al that I could find to a common macro in the same
series that I am introducing said common macro.

The first patch of the series introduces a new header file,
hw_bitfield.h, which contains two new macros: FIELD_PREP_WM16 and
FIELD_PREP_WM16_CONST. The latter can be used in initializers.

I've cheekily added the hw_bitfield.h header to the BITMAP API section
of the MAINTAINERS file.

This macro definition checks that the mask fits, and that the value fits
in the mask. Like FIELD_PREP, it also shifts the value up to the mask,
so turning off a bit does not require using the mask as a value. Masks
are also required to be contiguous, like with FIELD_PREP.

For each definition of such a macro, the driver(s) that used it were
evaluated for three different treatments:
- full conversion to the new macro, for cases where replacing the
implementation of the old macro wouldn't have worked, or where the
conversion was trivial. These are the most complex patches in this
series, as they sometimes have to pull apart definitions of masks
and values due to the new semantics, which require a contiguous
mask and shift the value for us.
- replacing the implementation of the old macro with an instance of the
new macro, done where I felt it made the patch much easier to review
because I didn't want to drop a big diff on people.
- skipping conversion entirely, usually because the mask is
non-constant and it's not trivial to make it constant. Sometimes an
added complication is that said non-constant mask is either used in a
path where runtime overhead may not be desirable, or in an
initializer.

Left out of conversion:
- drivers/mmc/host/sdhci-of-arasan.c: mask is non-constant.
- drivers/phy/rockchip/phy-rockchip-inno-csidphy.c: mask is
non-constant likely by way of runtime pointer dereferencing, even if
struct and members are made const.
- drivers/clk/rockchip/clk.h: way too many clock drivers use non-const
masks in the context of an initializer.

I will not be addressing these 3 remaining users in this series, as
implementing a runtime checked version on top of this and verifying that
it doesn't cause undue overhead just for 3 stragglers is a bit outside
the scope of wanting to get my RK3576 PWM series unblocked. Please have
mercy.

In total, I count 19 different occurrences of such a macro fixed out of
22 I found. The vast majority of these patches have either undergone
static testing to ensure the values end up the same during development,
or have been verified to not break the device the driver is for at
runtime. Only a handful are just compile-tested, and the individual
patches remark which ones those are.

This took a lot of manual work as this wasn't really something that
could be automated: code had to be refactored to ensure masks were
contiguous, made sense to how the hardware actually works and to human
readers, were constant, and that the code uses unshifted values.

Please note that I will not be resending the whole series again for
purely subjective cosmetic changes. This series touches a lot of
subsystems, which means many clashing tastes. You've had a week's notice
to get any low-effort naming nitpicks out of the way after v1. If you as
a maintainer are unhappy with a commit prefix or such, then you have my
express permission to modify it while applying the patch, so that I
don't need to bombard everyone else's inboxes again.

https://lore.kernel.org/all/aD8hB-qJ4Qm6IFuS@yury/ [1]

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
Changes in v3:
- Rebased onto next-20250825
- Link to v2: https://lore.kernel.org/r/20250623-byeword-update-v2-0-cf1fc08a2e1f@collabora.com

Changes in v2:
- rebase onto next-20250623. This involved solving two conflicts in
pcie-dw-rockchip.
- move new macros to a new hw_bitfield.h, and rename them to
FIELD_PREP_WM16*. All patches in the series have been updated to use
the new names.
- hw_bitfield.h: fix macro param re-use in FIELD_PREP_WM16. I don't know
if there's any way to do the same in FIELD_PREP_WM16_CONST, but the
bitfield.h FIELD_PREP functions don't do it for either, so I'm already
strictly better anyway.
- hw_bitfield.h: remove whitespace after cast operators.
- change newly introduced U literal suffixes to UL, as they are more
commonly used in the kernel.
- pcie-dw-rockchip: remove the legacy mode flag, as it's unused.
- Link to v1: https://lore.kernel.org/r/20250612-byeword-update-v1-0-f4afb8f6313f@collabora.com

---
Nicolas Frattaroli (20):
bitmap: introduce hardware-specific bitfield operations
mmc: dw_mmc-rockchip: switch to FIELD_PREP_WM16 macro
soc: rockchip: grf: switch to FIELD_PREP_WM16_CONST macro
media: synopsys: hdmirx: replace macros with bitfield variants
drm/rockchip: lvds: switch to FIELD_PREP_WM16 macro
phy: rockchip-emmc: switch to FIELD_PREP_WM16 macro
drm/rockchip: dsi: switch to FIELD_PREP_WM16* macros
drm/rockchip: vop2: switch to FIELD_PREP_WM16 macro
phy: rockchip-samsung-dcphy: switch to FIELD_PREP_WM16 macro
drm/rockchip: dw_hdmi_qp: switch to FIELD_PREP_WM16 macro
drm/rockchip: inno-hdmi: switch to FIELD_PREP_WM16 macro
phy: rockchip-usb: switch to FIELD_PREP_WM16 macro
drm/rockchip: dw_hdmi: switch to FIELD_PREP_WM16* macros
ASoC: rockchip: i2s-tdm: switch to FIELD_PREP_WM16_CONST macro
net: stmmac: dwmac-rk: switch to FIELD_PREP_WM16 macro
PCI: rockchip: Switch to FIELD_PREP_WM16* macros
PCI: dw-rockchip: Switch to FIELD_PREP_WM16 macro
PM / devfreq: rockchip-dfi: switch to FIELD_PREP_WM16 macro
clk: sp7021: switch to FIELD_PREP_WM16 macro
phy: rockchip-pcie: switch to FIELD_PREP_WM16 macro

MAINTAINERS | 1 +
drivers/clk/clk-sp7021.c | 22 ++--
drivers/devfreq/event/rockchip-dfi.c | 27 ++--
drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c | 142 ++++++++++-----------
drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 80 ++++++------
drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 68 +++++-----
drivers/gpu/drm/rockchip/inno_hdmi.c | 11 +-
drivers/gpu/drm/rockchip/rockchip_drm_vop2.h | 1 -
drivers/gpu/drm/rockchip/rockchip_lvds.h | 21 +--
drivers/gpu/drm/rockchip/rockchip_vop2_reg.c | 15 ++-
.../media/platform/synopsys/hdmirx/snps_hdmirx.h | 6 +-
drivers/mmc/host/dw_mmc-rockchip.c | 9 +-
drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c | 3 +-
drivers/pci/controller/dwc/pcie-dw-rockchip.c | 42 +++---
drivers/pci/controller/pcie-rockchip.h | 35 ++---
drivers/phy/rockchip/phy-rockchip-emmc.c | 3 +-
drivers/phy/rockchip/phy-rockchip-pcie.c | 70 +++-------
drivers/phy/rockchip/phy-rockchip-samsung-dcphy.c | 11 +-
drivers/phy/rockchip/phy-rockchip-usb.c | 51 +++-----
drivers/soc/rockchip/grf.c | 35 +++--
include/linux/hw_bitfield.h | 62 +++++++++
sound/soc/rockchip/rockchip_i2s_tdm.h | 4 +-
22 files changed, 366 insertions(+), 353 deletions(-)
---
base-commit: 0c5416a62c0e4df1b3f79b5c74c03cd48df51357
change-id: 20250610-byeword-update-445c0eea771d

Best regards,
--
Nicolas Frattaroli <nicolas.frattaroli@collabora.com>