[PATCH 0/5] SPI core CS delay fixes and additions

[PATCH 0/5] SPI core CS delay fixes and additions

[Hector Martin]

Commits f6c911f3308c ("spi: dt-bindings: Introduce
spi-cs-setup-ns property") and 33a2fde5f77b ("spi: Introduce
spi-cs-setup-ns property") introduced a new property to represent the
CS setup delay in the device tree, but they have some issues:

- The property is only parsed as a 16-bit integer number of nanoseconds,
  which limits the maximum value to ~65us. This is not a reasonable
  upper limit, as some devices might need a lot more.
- The property name is inconsistent with other delay properties, which
  use a "*-delay-ns" naming scheme.
- Only the setup delay is introduced, but not the related hold and
  inactive delay times.

This series fixes the issues and adds support for the two missing
properties. Please pull in the first 3 patches as fixes for 6.2, to
avoid introducing a problematic DT API in this release. The last two
patches can wait until 6.3, though are probably harmless to throw in
as fixes too, since they're trivial.

Hector Martin (2):
  spi: dt-bindings: Rename spi-cs-setup-ns to spi-cs-setup-delay-ns
  spi: Rename spi-cs-setup-ns property to spi-cs-setup-delay-ns

Janne Grunau (3):
  spi: Use a 32-bit DT property for spi-cs-setup-delay-ns
  spi: dt-bindings: Add hold/inactive CS delay peripheral properties
  spi: Parse hold/inactive CS delay values from the DT

 .../bindings/spi/spi-peripheral-props.yaml    | 14 +++++++++--
 drivers/spi/spi.c                             | 24 +++++++++++++++----
 2 files changed, 32 insertions(+), 6 deletions(-)

-- 
2.35.1

[PATCH 1/5] spi: dt-bindings: Rename spi-cs-setup-ns to spi-cs-setup-delay-ns

[Hector Martin]

Other delay values follow the delay-ns naming convention, so unify the
newly introduced spi-cs-setup-ns property for consistency.

Also fix a typo while we're here.

Fixes: f6c911f3308c ("spi: dt-bindings: Introduce spi-cs-setup-ns property")
Signed-off-by: Hector Martin <marcan@marcan.st>
---
 .../devicetree/bindings/spi/spi-peripheral-props.yaml         | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
index ead2cccf658f..9a60c0664bbe 100644
--- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
@@ -44,9 +44,9 @@ properties:
     description:
       Maximum SPI clocking speed of the device in Hz.
 
-  spi-cs-setup-ns:
+  spi-cs-setup-delay-ns:
     description:
-      Delay in nanosecods to be introduced by the controller after CS is
+      Delay in nanoseconds to be introduced by the controller after CS is
       asserted.
 
   spi-rx-bus-width:
-- 
2.35.1

[PATCH 2/5] spi: Rename spi-cs-setup-ns property to spi-cs-setup-delay-ns

[Hector Martin]

As mentioned in the corresponding DT binding commit, the naming scheme
for delay properties includes "delay" in the name, so let's keep that
consistent.

Fixes: 33a2fde5f77b ("spi: Introduce spi-cs-setup-ns property")
Signed-off-by: Hector Martin <marcan@marcan.st>
---
 drivers/spi/spi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 3cc7bb4d03de..15f174f4e056 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2310,7 +2310,7 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
 		spi->max_speed_hz = value;
 
-	if (!of_property_read_u16(nc, "spi-cs-setup-ns", &cs_setup)) {
+	if (!of_property_read_u16(nc, "spi-cs-setup-delay-ns", &cs_setup)) {
 		spi->cs_setup.value = cs_setup;
 		spi->cs_setup.unit = SPI_DELAY_UNIT_NSECS;
 	}
-- 
2.35.1

[PATCH 3/5] spi: Use a 32-bit DT property for spi-cs-setup-delay-ns

[Hector Martin]

From: Janne Grunau <j@jannau.net>

65us is not a reasonable maximum for this property, as some devices
might need a much longer setup time (e.g. those driven by firmware on
the other end). Plus, device tree property values are in 32-bit cells
and smaller widths should not be used without good reason.

Also move the logic to a helper function, since this will later be used
to parse other CS delay properties too.

Fixes: 33a2fde5f77b ("spi: Introduce spi-cs-setup-ns property")
Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Hector Martin <marcan@marcan.st>
---
 drivers/spi/spi.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 15f174f4e056..370e4c85dc54 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2220,6 +2220,22 @@ void spi_flush_queue(struct spi_controller *ctlr)
 /*-------------------------------------------------------------------------*/
 
 #if defined(CONFIG_OF)
+static void of_spi_parse_dt_cs_delay(struct device_node *nc,
+				     struct spi_delay *delay, const char *prop)
+{
+	u32 value;
+
+	if (!of_property_read_u32(nc, prop, &value)) {
+		if (value > U16_MAX) {
+			delay->value = DIV_ROUND_UP(value, 1000);
+			delay->unit = SPI_DELAY_UNIT_USECS;
+		} else {
+			delay->value = value;
+			delay->unit = SPI_DELAY_UNIT_NSECS;
+		}
+	}
+}
+
 static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 			   struct device_node *nc)
 {
@@ -2310,10 +2326,8 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
 		spi->max_speed_hz = value;
 
-	if (!of_property_read_u16(nc, "spi-cs-setup-delay-ns", &cs_setup)) {
-		spi->cs_setup.value = cs_setup;
-		spi->cs_setup.unit = SPI_DELAY_UNIT_NSECS;
-	}
+	/* Device CS delays */
+	of_spi_parse_dt_cs_delay(nc, &spi->cs_setup, "spi-cs-setup-delay-ns");
 
 	return 0;
 }
-- 
2.35.1

Re: [PATCH 3/5] spi: Use a 32-bit DT property for spi-cs-setup-delay-ns

[Mark Brown]

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On Wed, Jan 04, 2023 at 06:36:29PM +0900, Janne Grunau wrote:

> 65us is not a reasonable maximum for this property, as some devices
> might need a much longer setup time (e.g. those driven by firmware on
> the other end). Plus, device tree property values are in 32-bit cells
> and smaller widths should not be used without good reason.

This breaks allmodconfig builds (I tested x86 but this should happen
for anything with -Werror):

/build/stage/linux/drivers/spi/spi.c: In function ‘of_spi_parse_dt’:
/build/stage/linux/drivers/spi/spi.c:2243:13: error: unused variable ‘cs_setup’ [-Werror=unused-variable]
 2243 |         u16 cs_setup;
      |             ^~~~~~~~
cc1: all warnings being treated as errors

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Re: [PATCH 3/5] spi: Use a 32-bit DT property for spi-cs-setup-delay-ns

[Hector Martin]

On 07/01/2023 01.26, Mark Brown wrote:
> On Wed, Jan 04, 2023 at 06:36:29PM +0900, Janne Grunau wrote:
> 
>> 65us is not a reasonable maximum for this property, as some devices
>> might need a much longer setup time (e.g. those driven by firmware on
>> the other end). Plus, device tree property values are in 32-bit cells
>> and smaller widths should not be used without good reason.
> 
> This breaks allmodconfig builds (I tested x86 but this should happen
> for anything with -Werror):
> 
> /build/stage/linux/drivers/spi/spi.c: In function ‘of_spi_parse_dt’:
> /build/stage/linux/drivers/spi/spi.c:2243:13: error: unused variable ‘cs_setup’ [-Werror=unused-variable]
>  2243 |         u16 cs_setup;
>       |             ^~~~~~~~
> cc1: all warnings being treated as errors

Yeah, the kernel test robot caught this one too. Sorry for missing it
(it got buried in warning noise in a rather large rebuild on my side).
That line should've been removed in #3 :(

I see two patches got applied already. Do you want me to just respin #3-#5?

- Hector

Re: [PATCH 3/5] spi: Use a 32-bit DT property for spi-cs-setup-delay-ns

[Mark Brown]

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On Sat, Jan 07, 2023 at 01:40:49AM +0900, Hector Martin wrote:

> Yeah, the kernel test robot caught this one too. Sorry for missing it
> (it got buried in warning noise in a rather large rebuild on my side).
> That line should've been removed in #3 :(

> I see two patches got applied already. Do you want me to just respin #3-#5?

Yes, please.

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[PATCH 4/5] spi: dt-bindings: Add hold/inactive CS delay peripheral properties

[Hector Martin]

From: Janne Grunau <j@jannau.net>

These two properties complete the bindings for the Linux spi_device cs
model, which includes cs_setup, cs_hold and cs_inactive delay values.

Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Hector Martin <marcan@marcan.st>
---
 .../devicetree/bindings/spi/spi-peripheral-props.yaml  | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
index 9a60c0664bbe..782a014b63a7 100644
--- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
@@ -49,6 +49,16 @@ properties:
       Delay in nanoseconds to be introduced by the controller after CS is
       asserted.
 
+  spi-cs-hold-delay-ns:
+    description:
+      Delay in nanoseconds to be introduced by the controller before CS is
+      de-asserted.
+
+  spi-cs-inactive-delay-ns:
+    description:
+      Delay in nanoseconds to be introduced by the controller after CS is
+      de-asserted.
+
   spi-rx-bus-width:
     description:
       Bus width to the SPI bus used for read transfers.
-- 
2.35.1

Re: [PATCH 4/5] spi: dt-bindings: Add hold/inactive CS delay peripheral properties

[Rob Herring]

On Wed, 04 Jan 2023 18:36:30 +0900, Hector Martin wrote:
> From: Janne Grunau <j@jannau.net>
> 
> These two properties complete the bindings for the Linux spi_device cs
> model, which includes cs_setup, cs_hold and cs_inactive delay values.
> 
> Signed-off-by: Janne Grunau <j@jannau.net>
> Signed-off-by: Hector Martin <marcan@marcan.st>
> ---
>  .../devicetree/bindings/spi/spi-peripheral-props.yaml  | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[PATCH 5/5] spi: Parse hold/inactive CS delay values from the DT

[Hector Martin]

From: Janne Grunau <j@jannau.net>

Now that we support parsing the setup time from the Device Tree, we can
also easily support the remaining hold and inactive time delay values.

Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Hector Martin <marcan@marcan.st>
---
 drivers/spi/spi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 370e4c85dc54..0d84f90ab218 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2328,6 +2328,8 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 
 	/* Device CS delays */
 	of_spi_parse_dt_cs_delay(nc, &spi->cs_setup, "spi-cs-setup-delay-ns");
+	of_spi_parse_dt_cs_delay(nc, &spi->cs_hold, "spi-cs-hold-delay-ns");
+	of_spi_parse_dt_cs_delay(nc, &spi->cs_inactive, "spi-cs-inactive-delay-ns");
 
 	return 0;
 }
-- 
2.35.1

Re: [PATCH 0/5] SPI core CS delay fixes and additions

[Mark Brown]

On Wed, 04 Jan 2023 18:36:26 +0900, Hector Martin wrote:
> Commits f6c911f3308c ("spi: dt-bindings: Introduce
> spi-cs-setup-ns property") and 33a2fde5f77b ("spi: Introduce
> spi-cs-setup-ns property") introduced a new property to represent the
> CS setup delay in the device tree, but they have some issues:
> 
> - The property is only parsed as a 16-bit integer number of nanoseconds,
>   which limits the maximum value to ~65us. This is not a reasonable
>   upper limit, as some devices might need a lot more.
> - The property name is inconsistent with other delay properties, which
>   use a "*-delay-ns" naming scheme.
> - Only the setup delay is introduced, but not the related hold and
>   inactive delay times.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/5] spi: dt-bindings: Rename spi-cs-setup-ns to spi-cs-setup-delay-ns
      commit: 38892ea4cefbb6ed3a91e76d3af84a1f8077d2d4
[2/5] spi: Rename spi-cs-setup-ns property to spi-cs-setup-delay-ns
      commit: e0fe6a31cac84735939c29d1e05055d58325c6c0
[3/5] spi: Use a 32-bit DT property for spi-cs-setup-delay-ns
      (no commit info)
[4/5] spi: dt-bindings: Add hold/inactive CS delay peripheral properties
      (no commit info)
[5/5] spi: Parse hold/inactive CS delay values from the DT
      (no commit info)

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