This series adds the support for the omap-mcspi multi mode which allows
sending SPI messages with a shorter delay between CS and the message.
One drawback of the multi-mode is that the CS is raised between each word,
so it can only be used with messages containing 1 word transfers and
asking for cs_change. Few devices, like FPGAs, may easily workaround this
limitation.
The first patch removes the current implementation, which is working, but
don't comply with what is asked in the spi transfer (The CS is raised by
the hardware regardless of cs_change state). No drivers or board file use this
implementation upstream.
The second patch adds the implementation of the multi-mode, which complies
with what is asked in the SPI message.
The third patch is the suggested optimization for using MULTI mode in more
situations.
Signed-off-by: Louis Chauvet <[email protected]>
---
Changes in v3:
- Fix compilation warnings found with allmodconfig
- Link to v2: https://lore.kernel.org/r/20240223-spi-omap2-mcspi-multi-mode-v2-0-afe94476b9c3@bootlin.com
Changes in v2:
- Updated the commit line for the first patch to use the correct format;
- Updated the commit message for the second patch, adding precision on how
the controler works;
- Added the suggestion from Mark Brown to merge multiple transfers word
into one when applicable;
- Link to v1: https://lore.kernel.org/r/20240126-spi-omap2-mcspi-multi-mode-v1-0-d143d33f0fe0@bootlin.com
---
Louis Chauvet (3):
spi: spi-omap2-mcspi.c: revert "Toggle CS after each word"
spi: omap2-mcspi: Add support for MULTI-mode
spi: omap2-mcpsi: Enable MULTI-mode in more situations
drivers/spi/spi-omap2-mcspi.c | 95 +++++++++++++++++++++------
include/linux/platform_data/spi-omap2-mcspi.h | 3 -
2 files changed, 74 insertions(+), 24 deletions(-)
---
base-commit: 4cece764965020c22cff7665b18a012006359095
change-id: 20240126-spi-omap2-mcspi-multi-mode-e62f68b78ad3
Best regards,
--
Louis Chauvet <[email protected]>
Commit 5cbc7ca987fb ("spi: spi-omap2-mcspi.c: Toggle CS after each
word") introduced the toggling of CS after each word for the omap2-mcspi
controller.
The implementation is not respectful of the actual spi_message
content, so the CS can be raised after each word even if the
transfer structure asks to keep the CS active for the whole operation.
As it is not used anyway in the current Linux tree, it can be safely
removed.
Signed-off-by: Louis Chauvet <[email protected]>
---
drivers/spi/spi-omap2-mcspi.c | 15 ---------------
include/linux/platform_data/spi-omap2-mcspi.h | 3 ---
2 files changed, 18 deletions(-)
diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index ddf1c684bcc7..601acec37eca 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -1175,13 +1175,6 @@ static int omap2_mcspi_transfer_one(struct spi_controller *ctlr,
t->bits_per_word == spi->bits_per_word)
par_override = 0;
}
- if (cd && cd->cs_per_word) {
- chconf = mcspi->ctx.modulctrl;
- chconf &= ~OMAP2_MCSPI_MODULCTRL_SINGLE;
- mcspi_write_reg(ctlr, OMAP2_MCSPI_MODULCTRL, chconf);
- mcspi->ctx.modulctrl =
- mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL);
- }
chconf = mcspi_cached_chconf0(spi);
chconf &= ~OMAP2_MCSPI_CHCONF_TRM_MASK;
@@ -1240,14 +1233,6 @@ static int omap2_mcspi_transfer_one(struct spi_controller *ctlr,
status = omap2_mcspi_setup_transfer(spi, NULL);
}
- if (cd && cd->cs_per_word) {
- chconf = mcspi->ctx.modulctrl;
- chconf |= OMAP2_MCSPI_MODULCTRL_SINGLE;
- mcspi_write_reg(ctlr, OMAP2_MCSPI_MODULCTRL, chconf);
- mcspi->ctx.modulctrl =
- mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL);
- }
-
omap2_mcspi_set_enable(spi, 0);
if (spi_get_csgpiod(spi, 0))
diff --git a/include/linux/platform_data/spi-omap2-mcspi.h b/include/linux/platform_data/spi-omap2-mcspi.h
index 3b400b1919a9..9e3c15b4ac91 100644
--- a/include/linux/platform_data/spi-omap2-mcspi.h
+++ b/include/linux/platform_data/spi-omap2-mcspi.h
@@ -16,9 +16,6 @@ struct omap2_mcspi_platform_config {
struct omap2_mcspi_device_config {
unsigned turbo_mode:1;
-
- /* toggle chip select after every word */
- unsigned cs_per_word:1;
};
#endif
--
2.43.0
On Wed, 27 Mar 2024 09:43:35 +0100, Louis Chauvet wrote:
> This series adds the support for the omap-mcspi multi mode which allows
> sending SPI messages with a shorter delay between CS and the message.
>
> One drawback of the multi-mode is that the CS is raised between each word,
> so it can only be used with messages containing 1 word transfers and
> asking for cs_change. Few devices, like FPGAs, may easily workaround this
> limitation.
>
> [...]
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next
Thanks!
[1/3] spi: spi-omap2-mcspi.c: revert "Toggle CS after each word"
commit: 67bb37c05a6b56e0e1f804706145a52f655af3f1
[2/3] spi: omap2-mcspi: Add support for MULTI-mode
commit: d153ff4056cb346fd6182a8a1bea6e12b714b64f
[3/3] spi: omap2-mcpsi: Enable MULTI-mode in more situations
commit: e64d3b6fc9a388d7dc516668651cf4404bffec9b
All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.
You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.
If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.
Please add any relevant lists and maintainers to the CCs when replying
to this mail.
Thanks,
Mark