kernel/linux.git/drivers/base/regmap/regcache.c, branch v6.6.2

regmap: Merge up fixes from mainline

2023-07-23T22:34:06+00:00

There's several things here that will really help my CI.

regcache: Push async I/O request down into the rbtree cache

2023-07-19T11:58:42+00:00

Currently the regcache core unconditionally enables async I/O for all cache types, causing problems for the maple tree cache which dynamically allocates the buffers used to write registers to the device since async requires the buffers to be kept around until the I/O has been completed. This use of async I/O is mainly for the rbtree cache which stores data in a format directly usable for regmap_raw_write(), though there is a special case for single register writes which would also have allowed it to be used with the flat cache. It is a bit of a landmine for other caches since it implicitly converts sync operations to async, and with modern hardware it is not clear that async I/O is actually a performance win as shown by the performance work David Jander did with SPI. In multi core systems the cost of managing concurrency ends up swamping the performance benefit and almost all modern systems are multi core. Address this by pushing the enablement of async I/O down into the rbtree cache where it is actively used, avoiding surprises for other cache implementations. Reported-by: Charles Keepax Fixes: bfa0b38c1483 ("regmap: maple: Implement block sync for the maple tree cache") Reviewed-by: Charles Keepax Tested-by: Charles Keepax Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20230719-regcache-async-rbtree-v1-1-b03d30cf1daf@kernel.org Signed-off-by: Mark Brown

regmap: Let users check if a register is cached

2023-07-18T14:05:10+00:00

The HDA driver has a use case for checking if a register is cached which it bodges in awkwardly and unclearly. Provide an API which allows it to directly do what it's trying to do. Reviewed-by: Takashi Iwai Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20230717-regmap-cache-check-v1-1-73ef688afae3@kernel.org Signed-off-by: Mark Brown

regmap: cache: Revert "Add 64-bit mode support"

2023-07-09T21:48:45+00:00

There is no support for 64-bit data size in regmap, so there is no point to have it in regmap cache. This reverts commit 8b7663de6e2bfe3c40e1846e1c4625f33d138757. Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20230622183613.58762-3-andriy.shevchenko@linux.intel.com Signed-off-by: Mark Brown

Merge tag 'regmap-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap

2023-06-28T20:26:19+00:00

Pull regmap updates from Mark Brown: "Another busy release for regmap with the second half of the maple tree register cache implementation, there's some smaller optimisations that could be done but this should now be able to replace the rbtree cache for most devices. We also had a followup from Aidan MacDonald's refactoring of some of the regmap-irq interfaces, the conversion is complete so the old interfaces are removed. This means that even with the new features for the maple tree cache we'd have a nice negative diffstat were it not for the addition of a bunch more KUnit coverage. There's one GPIO patch in here, it was a dependency for a cleanup of an API in the regmap-irq code for which the gpio-104-dio-48e driver was the only user. Highlights: - The maple tree cache can now load in default values more efficiently, and is capabale of syncing multiple registers in a single write during cache sync - More KUnit coverage, including some coverage for raw I/O and a dummy RAM backed cache to support it - Removal of several old interfaces in regmap-irq now all users have been modernised" * tag 'regmap-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap: (23 commits) regmap: Allow reads from write only registers with the flat cache regmap: Drop early readability check regmap: Check for register readability before checking cache during read regmap: Add test to make sure we don't sync to read only registers regmap: Add a test case for write only registers regmap: Add test that writes to write only registers are prevented regmap: Add debugfs file for forcing field writes regmap: Don't check for changes in regcache_set_val() regmap: maple: Implement block sync for the maple tree cache regmap: Provide basic KUnit coverage for the raw register I/O regmap: Provide a ram backed regmap with raw support regmap: Add missing cache_only checks regmap: regmap-irq: Move handle_post_irq to before pm_runtime_put regmap: Load register defaults in blocks rather than register by register regmap: mmio: Allow passing an empty config->reg_stride regmap-irq: Drop backward compatibility for inverted mask/unmask regmap-irq: Minor adjustments to .handle_mask_sync() regmap-irq: Remove support for not_fixed_stride regmap-irq: Remove type registers regmap-irq: Remove virtual registers ...

regmap: regcache: Don't sync read-only registers

2023-06-13T12:15:00+00:00

regcache_maple_sync() tries to sync all cached values no matter whether it's writable or not. OTOH, regache_sync_val() does care the wrtability and returns -EIO for a read-only register. This results in an error message like: snd_hda_codec_realtek hdaudioC0D0: Unable to sync register 0x2f0009. -5 and the sync loop is aborted incompletely. This patch adds the writable register check to regcache_sync_val() for addressing the bug above. Note that, although we may add the check in the caller side (regcache_maple_sync()), here we put in regcache_sync_val(), so that a similar case like this can be avoided in future. Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache") Link: https://lore.kernel.org/r/877cs7g6f1.wl-tiwai@suse.de Signed-off-by: Takashi Iwai Link: https://lore.kernel.org/r/20230613112240.3361-1-tiwai@suse.de Signed-off-by: Mark Brown

regmap: Don't check for changes in regcache_set_val()

2023-06-12T13:51:07+00:00

The only user of regcache_set_val() ignores the return value so we may as well not bother checking if the value we are trying to set is the same as the value already stored. Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20230609-regcache-set-val-no-ret-v1-1-9a6932760cf8@kernel.org Signed-off-by: Mark Brown

regmap: maple: Implement block sync for the maple tree cache

2023-06-12T13:51:06+00:00

For register maps where we can write multiple values in a single bus operation it is generally much faster to do so. Improve the performance of maple tree cache syncs on such devices by identifying blocks of adjacent registers that need to be written out and combining them into a single operation. Combining writes does mean that we need to allocate a scratch buffer and format the data into it but it is expected that for most cases where caches are in use the cost of I/O will be much greater than the cost of doing the allocation and format. Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20230609-regcache-maple-sync-raw-v1-1-8ddeb4e2b9ab@kernel.org Signed-off-by: Mark Brown

regmap: Add maple tree based register cache

2023-04-03T11:53:44+00:00

The current state of the art for sparse register maps is the rbtree cache. This works well for most applications but isn't always ideal for sparser register maps since the rbtree can get deep, requiring a lot of walking. Fortunately the kernel has a data structure intended to address this very problem, the maple tree. Provide an initial implementation of a register cache based on the maple tree to start taking advantage of it. The entries stored in the maple tree are arrays of register values, with the maple tree keys holding the register addresses. We store data in host native format rather than device native format as we do for rbtree, this will be a benefit for devices where we don't marshal data within regmap and simplifies the code but will result in additional CPU overhead when syncing the cache on devices where we do marshal data in regmap. This should work well for a lot of devices, though there's some additional areas that could be looked at such as caching the last accessed entry like we do for rbtree and trying to minimise the maple tree level locking. We should also use bulk writes rather than single register writes when resyncing the cache where possible, even if we don't store in device native format. Very small register maps may continue to to better with rbtree longer term. Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20230325-regcache-maple-v3-2-23e271f93dc7@kernel.org Signed-off-by: Mark Brown

regmap: Factor out single value register syncing

2023-04-03T11:53:43+00:00

In order to support sparse caches that don't store data in raw format factor out the parts of the raw block sync implementation that deal with writing a single register via _regmap_write(). Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20230325-regcache-maple-v3-1-23e271f93dc7@kernel.org Signed-off-by: Mark Brown