Message-Id: <20250612-byeword-update-v1-0-f4afb8f6313f@collabora.com>
Date: Thu, 12 Jun 2025 20:56:02 +0200
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Yury Norov <yury.norov@...il.com>, 
 Rasmus Villemoes <linux@...musvillemoes.dk>, 
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Cc: kernel@...labora.com, linux-kernel@...r.kernel.org, 
 linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
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 linux-pm@...r.kernel.org, linux-clk@...r.kernel.org, llvm@...ts.linux.dev, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH 00/20] BYEWORD_UPDATE: unifying (most) HIWORD_UPDATE macros

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 the two new macros in
bitfield.h, called HWORD_UPDATE and HWORD_UPDATE_CONST. The latter can
be used in initializers.

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.

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

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
---
Nicolas Frattaroli (20):
      bitfield: introduce HWORD_UPDATE bitfield macros
      mmc: dw_mmc-rockchip: switch to HWORD_UPDATE macro
      soc: rockchip: grf: switch to HWORD_UPDATE_CONST macro
      media: synopsys: hdmirx: replace macros with bitfield variants
      drm/rockchip: lvds: switch to HWORD_UPDATE macro
      phy: rockchip-emmc: switch to HWORD_UPDATE macro
      drm/rockchip: dsi: switch to HWORD_UPDATE* macros
      drm/rockchip: vop2: switch to HWORD_UPDATE macro
      phy: rockchip-samsung-dcphy: switch to HWORD_UPDATE macro
      drm/rockchip: dw_hdmi_qp: switch to HWORD_UPDATE macro
      drm/rockchip: inno-hdmi: switch to HWORD_UPDATE macro
      phy: rockchip-usb: switch to HWORD_UPDATE macro
      drm/rockchip: dw_hdmi: switch to HWORD_UPDATE* macros
      ASoC: rockchip: i2s-tdm: switch to HWORD_UPDATE_CONST macro
      net: stmmac: dwmac-rk: switch to HWORD_UPDATE macro
      PCI: rockchip: switch to HWORD_UPDATE* macros
      PCI: dw-rockchip: switch to HWORD_UPDATE macro
      PM / devfreq: rockchip-dfi: switch to HWORD_UPDATE macro
      clk: sp7021: switch to HWORD_UPDATE macro
      phy: rockchip-pcie: switch to HWORD_UPDATE macro

 drivers/clk/clk-sp7021.c                           |  21 +--
 drivers/devfreq/event/rockchip-dfi.c               |  26 ++--
 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       |  14 +-
 .../media/platform/synopsys/hdmirx/snps_hdmirx.h   |   5 +-
 drivers/mmc/host/dw_mmc-rockchip.c                 |   7 +-
 drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c     |   3 +-
 drivers/pci/controller/dwc/pcie-dw-rockchip.c      |  39 +++---
 drivers/pci/controller/pcie-rockchip.h             |  35 ++---
 drivers/phy/rockchip/phy-rockchip-emmc.c           |   3 +-
 drivers/phy/rockchip/phy-rockchip-pcie.c           |  72 +++--------
 drivers/phy/rockchip/phy-rockchip-samsung-dcphy.c  |  10 +-
 drivers/phy/rockchip/phy-rockchip-usb.c            |  51 +++-----
 drivers/soc/rockchip/grf.c                         |  35 +++--
 include/linux/bitfield.h                           |  47 +++++++
 sound/soc/rockchip/rockchip_i2s_tdm.h              |   4 +-
 21 files changed, 342 insertions(+), 353 deletions(-)
---
base-commit: d9946fe286439c2aeaa7953b8c316efe5b83d515
change-id: 20250610-byeword-update-445c0eea771d

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

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