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Marc Kleine-Budde df75470b31 spi: spi-imx: imx51: revert burst length calculation back to bits_per_word The patch `15a6af94a2` ("spi: Increase imx51 ecspi burst length based on transfer length") increased the burst length calculation in mx51_ecspi_prepare_transfer() to be based on the transfer length. This breaks HW CS + SPI_CS_WORD support which was added in `6e95b23a5b` ("spi: imx: Implement support for CS_WORD") and transfers with bits-per-word != 8, 16, 32. SPI_CS_WORD means the CS should be toggled after each word. The implementation in the imx-spi driver relies on the fact that the HW CS is toggled automatically by the controller after each burst length number of bits. Setting the burst length to the number of bits of the _whole_ message breaks this use case. Further the patch `15a6af94a2` ("spi: Increase imx51 ecspi burst length based on transfer length") claims to optimize the transfers. But even without this patch, on modern spi-imx controllers with "dynamic_burst = true" (imx51, imx6 and newer), the transfers are already optimized, i.e. the burst length is dynamically adjusted in spi_imx_push() to avoid the pause between the SPI bursts. This has been confirmed by a scope measurement on an imx6d. Subsequent Patches tried to fix these and other problems: - `5f66db08cb` ("spi: imx: Take in account bits per word instead of assuming 8-bits") - `e9b220aeac` ("spi: spi-imx: correctly configure burst length when using dma") - `c712c05e46` ("spi: imx: fix the burst length at DMA mode and CPU mode") - `cf6d79a0f5` ("spi: spi-imx: fix off-by-one in mx51 CPU mode burst length") but the HW CS + SPI_CS_WORD use case is still broken. To fix the problems revert the burst size calculation in mx51_ecspi_prepare_transfer() back to the original form, before `15a6af94a2` ("spi: Increase imx51 ecspi burst length based on transfer length") was applied. Cc: Stefan Moring <stefan.moring@technolution.nl> Cc: Stefan Bigler <linux@bigler.io> Cc: Clark Wang <xiaoning.wang@nxp.com> Cc: Carlos Song <carlos.song@nxp.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Thorsten Scherer <T.Scherer@eckelmann.de> Fixes: `15a6af94a2` ("spi: Increase imx51 ecspi burst length based on transfer length") Fixes: `5f66db08cb` ("spi: imx: Take in account bits per word instead of assuming 8-bits") Fixes: `e9b220aeac` ("spi: spi-imx: correctly configure burst length when using dma") Fixes: `c712c05e46` ("spi: imx: fix the burst length at DMA mode and CPU mode") Fixes: `cf6d79a0f5` ("spi: spi-imx: fix off-by-one in mx51 CPU mode burst length") Link: https://lore.kernel.org/all/20240618-oxpecker-of-ideal-mastery-db59f8-mkl@pengutronix.de Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Tested-by: Thorsten Scherer <t.scherer@eckelmann.de> Link: https://msgid.link/r/20240618-spi-imx-fix-bustlength-v1-1-2053dd5fdf87@pengutronix.de Signed-off-by: Mark Brown <broonie@kernel.org>		2024-06-19 14:07:13 +01:00
arch	Miscellaneous topology parsing fixes:	2024-06-02 09:32:34 -07:00
block	blk-throttle: Fix incorrect display of io.max	2024-05-30 19:44:29 -06:00
certs	kbuild: use $(src) instead of $(srctree)/$(src) for source directory	2024-05-10 04:34:52 +09:00
crypto	This push fixes a bug in the new ecc P521 code as well as a buggy	2024-05-20 08:47:54 -07:00
Documentation	dma-mapping fixes for Linux 6.10	2024-05-31 12:14:55 -07:00
drivers	spi: spi-imx: imx51: revert burst length calculation back to bits_per_word	2024-06-19 14:07:13 +01:00
fs	2 small smb3 fixes	2024-06-01 14:35:57 -07:00
include	spi: Fix OCTAL mode support	2024-06-18 14:48:27 +01:00
init	Driver core changes for 6.10-rc1	2024-05-22 12:13:40 -07:00
io_uring	io_uring/net: assign kmsg inq/flags before buffer selection	2024-05-30 14:04:37 -06:00
ipc	Mainly singleton patches, documented in their respective changelogs.	2024-05-19 14:02:03 -07:00
kernel	Kbuild fixes for v6.10	2024-06-01 09:33:55 -07:00
lib	kunit/fortify: Remove __kmalloc_node() test	2024-05-31 13:47:41 -07:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	16 hotfixes, 11 of which are cc:stable.	2024-05-25 15:10:33 -07:00
net	Including fixes from bpf and netfilter.	2024-05-30 08:33:04 -07:00
rust	LoongArch changes for v6.10	2024-05-22 09:43:07 -07:00
samples	tracing/treewide: Remove second parameter of __assign_str()	2024-05-22 20:14:47 -04:00
scripts	dt-bindings: kbuild: Fix dt_binding_check on unconfigured build	2024-05-30 01:15:58 +09:00
security	landlock: Fix d_parent walk	2024-05-31 16:41:52 +02:00
sound	ALSA: seq: ump: Fix swapped song position pointer data	2024-05-31 09:51:44 +02:00
tools	Landlock fix for v6.10-rc2	2024-06-01 08:28:24 -07:00
usr	kbuild: use $(src) instead of $(srctree)/$(src) for source directory	2024-05-10 04:34:52 +09:00
virt	The usual shower of singleton fixes and minor series all over MM,	2024-05-19 09:21:03 -07:00
.clang-format	clang-format: Update with v6.7-rc4's `for_each` macro list	2023-12-08 23:54:38 +01:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.editorconfig	Add .editorconfig file for basic formatting	2023-12-28 16:22:47 +09:00
.get_maintainer.ignore	Add Jeff Kirsher to .get_maintainer.ignore	2024-03-08 11:36:54 +00:00
.gitattributes	.gitattributes: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	kbuild: create a list of all built DTB files	2024-02-19 18:20:39 +09:00
.mailmap	mailmap: update entry for Kees Cook	2024-05-31 08:58:36 -07:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: Drop Gustavo Pimentel as PCI DWC Maintainer	2024-03-27 13:41:02 -05:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	sound fixes for 6.10-rc2	2024-05-31 12:11:44 -07:00
Makefile	Linux 6.10-rc2	2024-06-02 15:44:56 -07:00
README	README: Fix spelling	2024-03-18 03:36:32 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.