This is a note to let you know that I've just added the patch titled
spi: Reintroduce spi_set_cs_timing()
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
spi-reintroduce-spi_set_cs_timing.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3009ab5427304d3514cdb9c6b147c5dbdb158c47
Author: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx>
Date: Thu Nov 17 12:52:44 2022 +0200
spi: Reintroduce spi_set_cs_timing()
[ Upstream commit 684a47847ae639689e7b823251975348a8e5434f ]
commit 4ccf359849ce ("spi: remove spi_set_cs_timing()"), removed the
method as noboby used it. Nobody used it probably because some SPI
controllers use some default large cs-setup time that covers the usual
cs-setup time required by the spi devices. There are though SPI controllers
that have a smaller granularity for the cs-setup time and their default
value can't fulfill the spi device requirements. That's the case for the
at91 QSPI IPs where the default cs-setup time is half of the QSPI clock
period. This was observed when using an sst26vf064b SPI NOR flash which
needs a spi-cs-setup-ns = <7>; in order to be operated close to its maximum
104 MHz frequency.
Call spi_set_cs_timing() in spi_setup() just before calling spi_set_cs(),
as the latter needs the CS timings already set.
If spi->controller->set_cs_timing is not set, the method will return 0.
There's no functional impact expected for the existing drivers. Even if the
spi-mt65xx.c and spi-tegra114.c drivers set the set_cs_timing method,
there's no user for them as of now. The only tested user of this support
will be a SPI NOR flash that comunicates with the Atmel QSPI controller for
which the support follows in the next patches.
One will notice that this support is a bit different from the one that was
removed in commit 4ccf359849ce ("spi: remove spi_set_cs_timing()"),
because this patch adapts to the changes done after the removal: the move
of the cs delays to the spi device, the retirement of the lelgacy GPIO
handling. The mutex handling was removed from spi_set_cs_timing() because
we now always call spi_set_cs_timing() in spi_setup(), which already
handles the spi->controller->io_mutex, so use the mutex handling from
spi_setup().
Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221117105249.115649-4-tudor.ambarus@xxxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Stable-dep-of: fc70d643a2f6 ("spi: atmel: Fix clock issue when using devices with different polarities")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index dfce0f7d4c640..f1ed2863a183e 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -3623,6 +3623,37 @@ static int __spi_validate_bits_per_word(struct spi_controller *ctlr,
return 0;
}
+/**
+ * spi_set_cs_timing - configure CS setup, hold, and inactive delays
+ * @spi: the device that requires specific CS timing configuration
+ *
+ * Return: zero on success, else a negative error code.
+ */
+static int spi_set_cs_timing(struct spi_device *spi)
+{
+ struct device *parent = spi->controller->dev.parent;
+ int status = 0;
+
+ if (spi->controller->set_cs_timing && !spi->cs_gpiod) {
+ if (spi->controller->auto_runtime_pm) {
+ status = pm_runtime_get_sync(parent);
+ if (status < 0) {
+ pm_runtime_put_noidle(parent);
+ dev_err(&spi->controller->dev, "Failed to power device: %d\n",
+ status);
+ return status;
+ }
+
+ status = spi->controller->set_cs_timing(spi);
+ pm_runtime_mark_last_busy(parent);
+ pm_runtime_put_autosuspend(parent);
+ } else {
+ status = spi->controller->set_cs_timing(spi);
+ }
+ }
+ return status;
+}
+
/**
* spi_setup - setup SPI mode and clock rate
* @spi: the device whose settings are being modified
@@ -3719,6 +3750,12 @@ int spi_setup(struct spi_device *spi)
}
}
+ status = spi_set_cs_timing(spi);
+ if (status) {
+ mutex_unlock(&spi->controller->io_mutex);
+ return status;
+ }
+
if (spi->controller->auto_runtime_pm && spi->controller->set_cs) {
status = pm_runtime_resume_and_get(spi->controller->dev.parent);
if (status < 0) {
