linux-kernel - [PATCH v1 0/3] regmap: Drop never (properly) worked 64-bit support

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Date:   Thu, 22 Jun 2023 21:36:10 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Mark Brown <broonie@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: [PATCH v1 0/3] regmap: Drop never (properly) worked 64-bit support

regmap API internally operates on unsigned int values for the register
offsets and data. The commit back in 2015 that introduces 64-bit
excerpts in the code made a false impression that it works. Not really.

Consider two things:
 1/ register offset
 2/ data

For the first one is very rarely we need (except probably an MMIO case)
it. Even though, it won't work due to 32-bit limitations of the base offset.
Considering, let's say, 4 bytes stride the current implementation may
cover 36-bit of address space _only_. And 37-bit for the 8 bytes stride.

For the second one it's obviously that we want _all_ bits to be covered
in the data (otherwise what's the point?) and unsigned int gives us
only 32-bits.

With all this, revert all 64-bit excerpts from regmap API to avoid
false impressions and new code that never works.

Note, there are no users with such sizes in the kernel.

Andy Shevchenko (3):
  regmap: Revert "add 64-bit mode support" and Co.
  regmap: cache: Revert "Add 64-bit mode support"
  regmap: mmio: Remove unused 64-bit support code

 drivers/base/regmap/regcache.c    |  15 ----
 drivers/base/regmap/regmap-mmio.c |  24 ------
 drivers/base/regmap/regmap.c      | 122 ------------------------------
 3 files changed, 161 deletions(-)

-- 
2.40.0.1.gaa8946217a0b