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Wysocki" , Danilo Krummrich , Sander Vanheule Subject: [PATCH v4 0/2] regmap: Introduce validity info for flat cache Date: Wed, 22 Oct 2025 22:04:06 +0200 Message-ID: <20251022200408.63027-1-sander@svanheule.net> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The flat cache behaves differently from the other caches, in that it has no way of knowing if a cache entry is valid. Initialization has to happen either by providing defaults, by loading defaults from hardware (via num_reg_defaults_raw), or by performing the required register writes. This difference in behavior may be unexpected to the user [1]. To provide feature parity between the different cache types, a new variant of the flat cache is proposed. This allows user to migrate to the sparse flat cache (or a different cache type) when possible. In order to encourage migration, the second patch adds a new warning to inform the user of their suspicious cache. [1] https://lore.kernel.org/linux-gpio/e461ca08-ad28-44fe-85f1-afe332c1d43d@topic.nl/ --- Changes since v3: Link: https://lore.kernel.org/lkml/20250109180256.6269-1-sander@svanheule.net/ - Split changes into two patches to provide a migration path Changes since v2: Link: https://lore.kernel.org/all/20250109151106.38645-1-sander@svanheule.net/ - Complete renaming of index variables so regcache-flat.c compiles again Changes since v1: Link: https://lore.kernel.org/all/20241231100256.194753-1-sander@svanheule.net/ - Fix off-by-one in length for bitmap_clear() - Add REGCACHE_FLAT to the list of sparse cache tests Sander Vanheule (2): regmap: add flat cache with sparse validity regmap: warn users about uninitialized flat cache drivers/base/regmap/internal.h | 1 + drivers/base/regmap/regcache-flat.c | 98 +++++++++++++++++++++++++---- drivers/base/regmap/regcache.c | 1 + drivers/base/regmap/regmap-kunit.c | 14 +++++ include/linux/regmap.h | 1 + 5 files changed, 104 insertions(+), 11 deletions(-) -- 2.51.0