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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Mark Brown <broonie@kernel.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>
Subject: [PATCH v1 0/3] regmap: Drop never (properly) worked 64-bit support
Date: Thu, 22 Jun 2023 21:36:10 +0300	[thread overview]
Message-ID: <20230622183613.58762-1-andriy.shevchenko@linux.intel.com> (raw)

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


             reply	other threads:[~2023-06-22 18:36 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-22 18:36 Andy Shevchenko [this message]
2023-06-22 18:36 ` [PATCH v1 1/3] regmap: Revert "add 64-bit mode support" and Co Andy Shevchenko
2023-06-22 18:36 ` [PATCH v1 2/3] regmap: cache: Revert "Add 64-bit mode support" Andy Shevchenko
2023-06-22 18:36 ` [PATCH v1 3/3] regmap: mmio: Remove unused 64-bit support code Andy Shevchenko
2023-07-12 11:47 ` [PATCH v1 0/3] regmap: Drop never (properly) worked 64-bit support Mark Brown

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