Hi all,
this is my third attempt to fix the ssd1307fb OLED driver reset. In the
second attempt [1] Rob suggested to take different aproach. That is to
apply what was originaly part of the first round and eventually merged
but reverted later on [2][3].
The last patch in this series is a fixup for the single user (in-tree)
that uses this OLED. Rob suggested the fixup may actually be applied
only after someone complains their display broke.
And a comment from Alexandre regarding the status of the Crystalfontz
platform:
On 20.12.2018 13:35, Alexandre Belloni wrote:
> Honestly, the platform has been discontinued and I don't really think
> it is worth having that fixup in the tree forever.
Thank you,
Michal
[1] https://patchwork.kernel.org/patch/10665597/#22327227
[2] https://patchwork.kernel.org/patch/10617729/
[3] https://patchwork.kernel.org/patch/10617731/#22257175
Michal Vokáč (4):
dt-bindings: display: ssd1307fb: Remove reset-active-low from examples
video: ssd1307fb: Do not hard code active-low reset sequence
ARM: dts: imx28-cfa10036: Fix the reset gpio signal polarity
ARM: mxs: cfa10036: Fixup OLED display reset polarity
.../devicetree/bindings/display/ssd1307fb.txt | 2 -
arch/arm/boot/dts/imx28-cfa10036.dts | 3 +-
arch/arm/mach-mxs/mach-mxs.c | 44 ++++++++++++++++++++++
drivers/video/fbdev/ssd1307fb.c | 4 +-
4 files changed, 48 insertions(+), 5 deletions(-)
--
2.1.4
The reset signal of the SSD1306 OLED display is actually active-low.
Adapt the DT to reflect the real world.
Reviewed-by: Rob Herring <[email protected]>
Acked-by: Alexandre Belloni <[email protected]>
Signed-off-by: Michal Vokáč <[email protected]>
---
Changes in v2 resend:
- Add Acked-by from Alexandre.
Changes from v1:
- Add R-by from Rob
arch/arm/boot/dts/imx28-cfa10036.dts | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/imx28-cfa10036.dts b/arch/arm/boot/dts/imx28-cfa10036.dts
index d3e3622..de48b58 100644
--- a/arch/arm/boot/dts/imx28-cfa10036.dts
+++ b/arch/arm/boot/dts/imx28-cfa10036.dts
@@ -11,6 +11,7 @@
/dts-v1/;
#include "imx28.dtsi"
+#include <dt-bindings/gpio/gpio.h>
/ {
model = "Crystalfontz CFA-10036 Board";
@@ -96,7 +97,7 @@
pinctrl-names = "default";
pinctrl-0 = <&ssd1306_cfa10036>;
reg = <0x3c>;
- reset-gpios = <&gpio2 7 0>;
+ reset-gpios = <&gpio2 7 GPIO_ACTIVE_LOW>;
solomon,height = <32>;
solomon,width = <128>;
solomon,page-offset = <0>;
--
2.1.4
There was a bug in reset signal generation in ssd1307fb OLED driver.
The display needs an active-low reset signal but the driver produced
the correct sequence only if the GPIO used for reset was specified as
GPIO_ACTIVE_HIGH.
Now as the OLED driver is fixed it is also necessarry to implement
a fixup for all current users of the old DT ABI. There is only one
in-tree user and that is the Crystalfontz CFA-10036 board. In case
this board is booting and GPIO_ACTIVE_HIGH is used for reset we
override it to GPIO_ACTIVE_LOW.
Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Michal Vokáč <[email protected]>
---
Changes from v1:
- Add R-by from Rob
- Use of_property_read_variable_u32_array to read the GPIO specifier
array instead of reading it manualy in for cycle. (Rob)
arch/arm/mach-mxs/mach-mxs.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/arch/arm/mach-mxs/mach-mxs.c b/arch/arm/mach-mxs/mach-mxs.c
index 1c6062d..50038d6 100644
--- a/arch/arm/mach-mxs/mach-mxs.c
+++ b/arch/arm/mach-mxs/mach-mxs.c
@@ -21,6 +21,7 @@
#include <linux/reboot.h>
#include <linux/micrel_phy.h>
#include <linux/of_address.h>
+#include <linux/of_gpio.h>
#include <linux/of_platform.h>
#include <linux/phy.h>
#include <linux/pinctrl/consumer.h>
@@ -268,9 +269,52 @@ static void __init apx4devkit_init(void)
apx4devkit_phy_fixup);
}
+#define OLED_RESET_GPIO_LEN 3
+#define OLED_RESET_GPIO_SIZE (OLED_RESET_GPIO_LEN * sizeof(u32))
+
+static void __init crystalfontz_oled_reset_fixup(void)
+{
+ struct property *newgpio;
+ struct device_node *np;
+ u32 *gpiospec;
+ int ret;
+
+ np = of_find_compatible_node(NULL, NULL, "solomon,ssd1306fb-i2c");
+ if (!np)
+ return;
+
+ newgpio = kzalloc(sizeof(*newgpio) + OLED_RESET_GPIO_SIZE, GFP_KERNEL);
+ if (!newgpio)
+ return;
+
+ newgpio->value = newgpio + 1;
+ newgpio->length = OLED_RESET_GPIO_SIZE;
+ newgpio->name = kstrdup("reset-gpios", GFP_KERNEL);
+ if (!newgpio->name) {
+ kfree(newgpio);
+ return;
+ }
+
+ gpiospec = newgpio->value;
+ ret = of_property_read_variable_u32_array(np, "reset-gpios", gpiospec,
+ OLED_RESET_GPIO_LEN, 0);
+
+ if (ret < 0) {
+ kfree(newgpio);
+ return;
+ }
+
+ if (!(gpiospec[2] & OF_GPIO_ACTIVE_LOW)) {
+ gpiospec[2] |= OF_GPIO_ACTIVE_LOW;
+ cpu_to_be32_array(gpiospec, gpiospec, OLED_RESET_GPIO_LEN);
+ of_update_property(np, newgpio);
+ }
+}
+
static void __init crystalfontz_init(void)
{
update_fec_mac_prop(OUI_CRYSTALFONTZ);
+ crystalfontz_oled_reset_fixup();
}
static void __init duckbill_init(void)
--
2.1.4
The SSD130x OLED display reset signal is active low. Now the reset
sequence is implemented in such a way that users are forced to
define reset-gpios as GPIO_ACTIVE_HIGH in DT to make the reset work.
Do not hard code the active-low sequence into the driver but instead
allow the user to specify the gpio as GPIO_ACTIVE_LOW to reflect
the real world.
Reviewed-by: Rob Herring <[email protected]>
Reviewed-by: Alexandre Belloni <[email protected]>
Signed-off-by: Michal Vokáč <[email protected]>
---
Changes in v2 resend:
- Add R-by from Alexandre.
Changes from v1:
- Add R-by from Rob
drivers/video/fbdev/ssd1307fb.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 4061a20..3b361bc 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -667,10 +667,10 @@ static int ssd1307fb_probe(struct i2c_client *client,
if (par->reset) {
/* Reset the screen */
- gpiod_set_value_cansleep(par->reset, 0);
- udelay(4);
gpiod_set_value_cansleep(par->reset, 1);
udelay(4);
+ gpiod_set_value_cansleep(par->reset, 0);
+ udelay(4);
}
if (par->vbat_reg) {
--
2.1.4
The reset-active-low property has been removed brom the binding a while
ago. So remove it from the examples as well.
Fixes: 519b4db ("fbdev: ssd1307fb: Remove reset-active-low from the DT binding document")
Reviewed-by: Rob Herring <[email protected]>
Reviewed-by: Alexandre Belloni <[email protected]>
Signed-off-by: Michal Vokáč <[email protected]>
---
Changes in v2 resend:
- Add R-by from Alexandre.
Changes from v1:
- Add R-by from Rob
Documentation/devicetree/bindings/display/ssd1307fb.txt | 2 --
1 file changed, 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/display/ssd1307fb.txt b/Documentation/devicetree/bindings/display/ssd1307fb.txt
index 209d931..b67f8ca 100644
--- a/Documentation/devicetree/bindings/display/ssd1307fb.txt
+++ b/Documentation/devicetree/bindings/display/ssd1307fb.txt
@@ -36,7 +36,6 @@ ssd1307: oled@3c {
reg = <0x3c>;
pwms = <&pwm 4 3000>;
reset-gpios = <&gpio2 7>;
- reset-active-low;
};
ssd1306: oled@3c {
@@ -44,7 +43,6 @@ ssd1306: oled@3c {
reg = <0x3c>;
pwms = <&pwm 4 3000>;
reset-gpios = <&gpio2 7>;
- reset-active-low;
solomon,com-lrremap;
solomon,com-invdir;
solomon,com-offset = <32>;
--
2.1.4