[PATCH v2 0/4] ARM: dts: at91: Set sst26vf064b SPI NOR flash at its maxumum frequency

[PATCH v2 0/4] ARM: dts: at91: Set sst26vf064b SPI NOR flash at its maxumum frequency

[Tudor Ambarus]

Hi, Nicolas!

I just compiled tested this with sama5_defconfig and at91_dt_defconfig.
Would you please do a simnple test on your side to make sure everything
is in place? A test on a single board would suffice
(maybe sama5d27-wlsom1-ek?):

#!/bin/sh

dd if=/dev/urandom of=./qspi_test bs=1M count=6
mtd_debug write /dev/mtd5 0 6291456 qspi_test
mtd_debug erase /dev/mtd5 0 6291456
mtd_debug read /dev/mtd5 0 6291456 qspi_read
hexdump qspi_read
mtd_debug write /dev/mtd5 0 6291456 qspi_test
mtd_debug read /dev/mtd5 0 6291456 qspi_read
sha1sum qspi_test qspi_read

Cheers,
ta

Changes in v2: update value of spi-cs-setup-ns as it was changed to u32
since the first proposal.
v1 at: https://lore.kernel.org/linux-mtd/20221117105249.115649-1-tudor.ambarus@microchip.com/

---
SPI NOR flashes have specific cs-setup time requirements without which
they can't work at frequencies close to their maximum supported frequency,
as they miss the first bits of the instruction command. Unrecognized
commands are ignored, thus the flash will be unresponsive. Introduce the
spi-cs-setup-ns property to allow spi devices to specify their cs setup
time.

Tudor Ambarus (4):
  ARM: dts: at91-sama5d27_wlsom1: Set sst26vf064b SPI NOR flash at its
    maximum frequency
  ARM: dts: at91-sama5d27_som1: Set sst26vf064b SPI NOR flash at its
    maximum frequency
  ARM: dts: at91: sama5d2_icp: Set sst26vf064b SPI NOR flash at its
    maximum frequency
  ARM: dts: at91: sam9x60ek: Set sst26vf064b SPI NOR flash at its
    maximum frequency

 arch/arm/boot/dts/at91-sam9x60ek.dts        | 3 ++-
 arch/arm/boot/dts/at91-sama5d27_som1.dtsi   | 3 ++-
 arch/arm/boot/dts/at91-sama5d27_wlsom1.dtsi | 3 ++-
 arch/arm/boot/dts/at91-sama5d2_icp.dts      | 3 ++-
 4 files changed, 8 insertions(+), 4 deletions(-)

-- 
2.40.0.348.gf938b09366-goog

[PATCH v2 1/4] ARM: dts: at91-sama5d27_wlsom1: Set sst26vf064b SPI NOR flash at its maximum frequency

[Tudor Ambarus]

From: Tudor Ambarus <tudor.ambarus@microchip.com>

sama5d27-wlsom1 populates an sst26vf064b SPI NOR flash. Its maximum
operating frequency for 2.7-3.6V is 104 MHz. As the flash is operated
at 3.3V, increase its maximum supported frequency to 104MHz. The
increasing of the spi-max-frequency value requires the setting of the
"CE# Not Active Hold Time", thus set the spi-cs-setup-ns to a value of 7.

The sst26vf064b datasheet specifies just a minimum value for the
"CE# Not Active Hold Time" and it advertises it to 5 ns. There's no
maximum time specified. I determined experimentally that 5 ns for the
spi-cs-setup-ns is not enough when the flash is operated close to its
maximum frequency and tests showed that 7 ns is just fine, so set the
spi-cs-setup-ns dt property to 7.

With the increase of frequency the reads are now faster with ~37%.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 arch/arm/boot/dts/at91-sama5d27_wlsom1.dtsi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/at91-sama5d27_wlsom1.dtsi b/arch/arm/boot/dts/at91-sama5d27_wlsom1.dtsi
index 83bcf9fe0152..4617805c7748 100644
--- a/arch/arm/boot/dts/at91-sama5d27_wlsom1.dtsi
+++ b/arch/arm/boot/dts/at91-sama5d27_wlsom1.dtsi
@@ -220,7 +220,8 @@ qspi1_flash: flash@0 {
 		#size-cells = <1>;
 		compatible = "jedec,spi-nor";
 		reg = <0>;
-		spi-max-frequency = <80000000>;
+		spi-max-frequency = <104000000>;
+		spi-cs-setup-ns = <7>;
 		spi-rx-bus-width = <4>;
 		spi-tx-bus-width = <4>;
 		m25p,fast-read;
-- 
2.40.0.348.gf938b09366-goog

[PATCH v2 2/4] ARM: dts: at91-sama5d27_som1: Set sst26vf064b SPI NOR flash at its maximum frequency

[Tudor Ambarus]

From: Tudor Ambarus <tudor.ambarus@microchip.com>

sama5d27-som1 populates an sst26vf064b SPI NOR flash. Its maximum
operating frequency for 2.7-3.6V is 104 MHz. As the flash is operated
at 3.3V, increase its maximum supported frequency to 104MHz. The
increasing of the spi-max-frequency value requires the setting of the
"CE# Not Active Hold Time", thus set the spi-cs-setup-ns to a value of 7.

The sst26vf064b datasheet specifies just a minimum value for the
"CE# Not Active Hold Time" and it advertises it to 5 ns. There's no
maximum time specified. I determined experimentally that 5 ns for the
spi-cs-setup-ns is not enough when the flash is operated close to its
maximum frequency and tests showed that 7 ns is just fine, so set the
spi-cs-setup-ns dt property to 7.

With the increase of frequency the reads are now faster with ~37%.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 arch/arm/boot/dts/at91-sama5d27_som1.dtsi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/at91-sama5d27_som1.dtsi b/arch/arm/boot/dts/at91-sama5d27_som1.dtsi
index 8aa9e8dea337..95ecb7d040a8 100644
--- a/arch/arm/boot/dts/at91-sama5d27_som1.dtsi
+++ b/arch/arm/boot/dts/at91-sama5d27_som1.dtsi
@@ -43,7 +43,8 @@ flash@0 {
 					#size-cells = <1>;
 					compatible = "jedec,spi-nor";
 					reg = <0>;
-					spi-max-frequency = <80000000>;
+					spi-max-frequency = <104000000>;
+					spi-cs-setup-ns = <7>;
 					spi-tx-bus-width = <4>;
 					spi-rx-bus-width = <4>;
 					m25p,fast-read;
-- 
2.40.0.348.gf938b09366-goog

[PATCH v2 3/4] ARM: dts: at91: sama5d2_icp: Set sst26vf064b SPI NOR flash at its maximum frequency

[Tudor Ambarus]

From: Tudor Ambarus <tudor.ambarus@microchip.com>

sama5d2_icp populates an sst26vf064b SPI NOR flash. Its maximum operating
frequency for 2.7-3.6V is 104 MHz. As the flash is operated at 3.3V,
increase its maximum supported frequency to 104MHz. The increasing of the
spi-max-frequency value requires the setting of the
"CE# Not Active Hold Time", thus set the spi-cs-setup-ns to a value of 7.

The sst26vf064b datasheet specifies just a minimum value for the
"CE# Not Active Hold Time" and it advertises it to 5 ns. There's no
maximum time specified. I determined experimentally that 5 ns for the
spi-cs-setup-ns is not enough when the flash is operated close to its
maximum frequency and tests showed that 7 ns is just fine, so set the
spi-cs-setup-ns dt property to 7.

With the increase of frequency the reads are now faster with ~37%.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 arch/arm/boot/dts/at91-sama5d2_icp.dts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/at91-sama5d2_icp.dts b/arch/arm/boot/dts/at91-sama5d2_icp.dts
index 1346b8f2b259..999adeca6f33 100644
--- a/arch/arm/boot/dts/at91-sama5d2_icp.dts
+++ b/arch/arm/boot/dts/at91-sama5d2_icp.dts
@@ -669,7 +669,8 @@ flash@0 {
 		#size-cells = <1>;
 		compatible = "jedec,spi-nor";
 		reg = <0>;
-		spi-max-frequency = <80000000>;
+		spi-max-frequency = <104000000>;
+		spi-cs-setup-ns = <7>;
 		spi-tx-bus-width = <4>;
 		spi-rx-bus-width = <4>;
 		m25p,fast-read;
-- 
2.40.0.348.gf938b09366-goog

[PATCH v2 4/4] ARM: dts: at91: sam9x60ek: Set sst26vf064b SPI NOR flash at its maximum frequency

[Tudor Ambarus]

From: Tudor Ambarus <tudor.ambarus@microchip.com>

sam9x60ek populates an sst26vf064b SPI NOR flash. Its maximum operating
frequency for 2.7-3.6V is 104 MHz. As the flash is operated at 3.3V,
increase its maximum supported frequency to 104MHz. The increasing of the
spi-max-frequency value requires the setting of the
"CE# Not Active Hold Time", thus set the spi-cs-setup-ns to a value of 7.

The sst26vf064b datasheet specifies just a minimum value for the
"CE# Not Active Hold Time" and it advertises it to 5 ns. There's no
maximum time specified. I determined experimentally that 5 ns for the
spi-cs-setup-ns is not enough when the flash is operated close to its
maximum frequency and tests showed that 7 ns is just fine, so set the
spi-cs-setup-ns dt property to 7.

With the increase of frequency the reads are now faster with ~33%.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 arch/arm/boot/dts/at91-sam9x60ek.dts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/at91-sam9x60ek.dts b/arch/arm/boot/dts/at91-sam9x60ek.dts
index 180e4b1aa2f6..5cd593028aff 100644
--- a/arch/arm/boot/dts/at91-sam9x60ek.dts
+++ b/arch/arm/boot/dts/at91-sam9x60ek.dts
@@ -578,7 +578,8 @@ flash@0 {
 		#size-cells = <1>;
 		compatible = "jedec,spi-nor";
 		reg = <0>;
-		spi-max-frequency = <80000000>;
+		spi-max-frequency = <104000000>;
+		spi-cs-setup-ns = <7>;
 		spi-tx-bus-width = <4>;
 		spi-rx-bus-width = <4>;
 		m25p,fast-read;
-- 
2.40.0.348.gf938b09366-goog