[PATCH v8 0/2] Add driver for Sharp Memory LCD

[PATCH v8 0/2] Add driver for Sharp Memory LCD

[Alex Lanzano]

This patch series add support for the monochrome Sharp Memory LCD
panels. This series is based off of the work done by Mehdi Djait.

References:
https://lore.kernel.org/dri-devel/71a9dbf4609dbba46026a31f60261830163a0b99.1701267411.git.mehdi.djait@bootlin.com/
https://www.sharpsde.com/fileadmin/products/Displays/2016_SDE_App_Note_for_Memory_LCD_programming_V1.3.pdf

Co-developed-by: Mehdi Djait <mehdi.djait@bootlin.com>
Signed-off-by: Mehdi Djait <mehdi.djait@bootlin.com>
Signed-off-by: Alex Lanzano <lanzano.alex@gmail.com>
---
Changes in v8:
- Addressed review comments from Uwe
    - Replace pwm_get_state with pwm_init_state
    - Use pwm_set_relative_duty_cycle instead of manually setting period and duty cycle

Changes in v7:
- Add Reviewed-by tag back to dt-binding patch

Changes in v6:
- Rebase off latest drm-misc-next
- Replace pwm_apply_state with pwm_apply_might_sleep

Changes in v5:
- Address minor style issues in sharp-memory.c

Changes in v4:
- Remove redundant dev_err

Changes in v3:
- Fix file path in MAINTAINERS file
- Address review comments
- Simplify mode selection based on match data instead of model

Changes in v2:
- Credited Mehdi Djait in commit messages
- Renamed sharp,sharp-memory.yaml to sharp,ls010b7dh04.yaml
- Using strings instead of int for vcom-mode in dt-binding
- Fixed indentation of binding example
- Removed binding header
- Removed extra whitespace in sharp-memory.c
- Fixed error handling in sharp-memory.c
- Added match data to of_device_id table to be in-sync with spi_device_id table
- Replaced redundant function with spi_get_device_match_data
- Sorted header files in sharp-memory.c
---

Alex Lanzano (2):
  dt-bindings: display: Add Sharp Memory LCD bindings
  drm/tiny: Add driver for Sharp Memory LCD

 .../bindings/display/sharp,ls010b7dh04.yaml   |  92 +++
 MAINTAINERS                                   |   6 +
 drivers/gpu/drm/tiny/Kconfig                  |  20 +
 drivers/gpu/drm/tiny/Makefile                 |   1 +
 drivers/gpu/drm/tiny/sharp-memory.c           | 681 ++++++++++++++++++
 5 files changed, 800 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/sharp,ls010b7dh04.yaml
 create mode 100644 drivers/gpu/drm/tiny/sharp-memory.c

-- 
2.46.2

[PATCH v8 1/2] dt-bindings: display: Add Sharp Memory LCD bindings

[Alex Lanzano]

Add device tree bindings for the monochrome Sharp Memory LCD

Co-developed-by: Mehdi Djait <mehdi.djait@bootlin.com>
Signed-off-by: Mehdi Djait <mehdi.djait@bootlin.com>
Signed-off-by: Alex Lanzano <lanzano.alex@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 .../bindings/display/sharp,ls010b7dh04.yaml   | 92 +++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/sharp,ls010b7dh04.yaml

diff --git a/Documentation/devicetree/bindings/display/sharp,ls010b7dh04.yaml b/Documentation/devicetree/bindings/display/sharp,ls010b7dh04.yaml
new file mode 100644
index 000000000000..8097f091c2a5
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/sharp,ls010b7dh04.yaml
@@ -0,0 +1,92 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/sharp,ls010b7dh04.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sharp Memory LCD panels
+
+maintainers:
+  - Alex Lanzano <lanzano.alex@gmail.com>
+
+description:
+  Sharp Memory LCDs are a series of monochrome displays that operate over
+  a SPI bus. The displays require a signal (VCOM) to be generated to prevent
+  DC bias build up resulting in pixels being unable to change. Three modes
+  can be used to provide the VCOM signal ("software", "external", "pwm").
+
+properties:
+  compatible:
+    enum:
+      - sharp,ls010b7dh04
+      - sharp,ls011b7dh03
+      - sharp,ls012b7dd01
+      - sharp,ls013b7dh03
+      - sharp,ls013b7dh05
+      - sharp,ls018b7dh02
+      - sharp,ls027b7dh01
+      - sharp,ls027b7dh01a
+      - sharp,ls032b7dd02
+      - sharp,ls044q7dh01
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 2000000
+
+  sharp,vcom-mode:
+    $ref: /schemas/types.yaml#/definitions/string
+    description: |
+      software - This mode relies on a software operation to send a
+      "maintain display" message to the display, toggling the vcom
+      bit on and off with each message
+
+      external - This mode relies on an external clock to generate
+      the signal on the EXTCOMM pin
+
+      pwm - This mode relies on a pwm device to generate the signal
+      on the EXTCOMM pin
+
+    enum: [software, external, pwm]
+
+  enable-gpios: true
+
+  pwms:
+    maxItems: 1
+    description: External VCOM signal
+
+required:
+  - compatible
+  - reg
+  - sharp,vcom-mode
+
+allOf:
+  - $ref: panel/panel-common.yaml#
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+  - if:
+      properties:
+        sharp,vcom-mode:
+          const: pwm
+    then:
+      required:
+        - pwms
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        display@0 {
+            compatible = "sharp,ls013b7dh03";
+            reg = <0>;
+            spi-cs-high;
+            spi-max-frequency = <1000000>;
+            sharp,vcom-mode = "software";
+        };
+    };
+...
-- 
2.46.2

[PATCH v8 2/2] drm/tiny: Add driver for Sharp Memory LCD

[Alex Lanzano]

Add support for the monochrome Sharp Memory LCDs.

Co-developed-by: Mehdi Djait <mehdi.djait@bootlin.com>
Signed-off-by: Mehdi Djait <mehdi.djait@bootlin.com>
Signed-off-by: Alex Lanzano <lanzano.alex@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 MAINTAINERS                         |   6 +
 drivers/gpu/drm/tiny/Kconfig        |  20 +
 drivers/gpu/drm/tiny/Makefile       |   1 +
 drivers/gpu/drm/tiny/sharp-memory.c | 681 ++++++++++++++++++++++++++++
 4 files changed, 708 insertions(+)
 create mode 100644 drivers/gpu/drm/tiny/sharp-memory.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5432239f3c5d..f3b1a6115711 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7289,6 +7289,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/display/panel/samsung,s6d7aa0.yaml
 F:	drivers/gpu/drm/panel/panel-samsung-s6d7aa0.c
 
+DRM DRIVER FOR SHARP MEMORY LCD
+M:	Alex Lanzano <lanzano.alex@gmail.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/display/sharp,ls010b7dh04.yaml
+F:	drivers/gpu/drm/tiny/sharp-memory.c
+
 DRM DRIVER FOR SITRONIX ST7586 PANELS
 M:	David Lechner <david@lechnology.com>
 S:	Maintained
diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index f6889f649bc1..bc386954faa2 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -186,6 +186,26 @@ config TINYDRM_REPAPER
 
 	  If M is selected the module will be called repaper.
 
+config TINYDRM_SHARP_MEMORY
+	tristate "DRM support for Sharp Memory LCD panels"
+	depends on DRM && SPI
+	select DRM_GEM_DMA_HELPER
+	select DRM_KMS_HELPER
+	help
+	  DRM Driver for the following Sharp Memory Panels:
+	  * 1.00" Sharp Memory LCD (LS010B7DH04)
+	  * 1.10" Sharp Memory LCD (LS011B7DH03)
+	  * 1.20" Sharp Memory LCD (LS012B7DD01)
+	  * 1.28" Sharp Memory LCD (LS013B7DH03)
+	  * 1.26" Sharp Memory LCD (LS013B7DH05)
+	  * 1.80" Sharp Memory LCD (LS018B7DH02)
+	  * 2.70" Sharp Memory LCD (LS027B7DH01)
+	  * 2.70" Sharp Memory LCD (LS027B7DH01A)
+	  * 3.20" Sharp Memory LCD (LS032B7DD02)
+	  * 4.40" Sharp Memory LCD (LS044Q7DH01)
+
+	  If M is selected the module will be called sharp_memory.
+
 config TINYDRM_ST7586
 	tristate "DRM support for Sitronix ST7586 display panels"
 	depends on DRM && SPI
diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
index 76dde89a044b..4aaf56f8707d 100644
--- a/drivers/gpu/drm/tiny/Makefile
+++ b/drivers/gpu/drm/tiny/Makefile
@@ -14,5 +14,6 @@ obj-$(CONFIG_TINYDRM_ILI9341)		+= ili9341.o
 obj-$(CONFIG_TINYDRM_ILI9486)		+= ili9486.o
 obj-$(CONFIG_TINYDRM_MI0283QT)		+= mi0283qt.o
 obj-$(CONFIG_TINYDRM_REPAPER)		+= repaper.o
+obj-$(CONFIG_TINYDRM_SHARP_MEMORY)	+= sharp-memory.o
 obj-$(CONFIG_TINYDRM_ST7586)		+= st7586.o
 obj-$(CONFIG_TINYDRM_ST7735R)		+= st7735r.o
diff --git a/drivers/gpu/drm/tiny/sharp-memory.c b/drivers/gpu/drm/tiny/sharp-memory.c
new file mode 100644
index 000000000000..7c527a0e2360
--- /dev/null
+++ b/drivers/gpu/drm/tiny/sharp-memory.c
@@ -0,0 +1,681 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_dma_helper.h>
+#include <drm/drm_fbdev_dma.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_dma_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_rect.h>
+#include <linux/bitrev.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/kthread.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pwm.h>
+#include <linux/spi/spi.h>
+
+#define SHARP_MODE_PERIOD 8
+#define SHARP_ADDR_PERIOD 8
+#define SHARP_DUMMY_PERIOD 8
+
+#define SHARP_MEMORY_DISPLAY_MAINTAIN_MODE 0
+#define SHARP_MEMORY_DISPLAY_UPDATE_MODE 1
+#define SHARP_MEMORY_DISPLAY_CLEAR_MODE 4
+
+enum sharp_memory_model {
+	LS010B7DH04,
+	LS011B7DH03,
+	LS012B7DD01,
+	LS013B7DH03,
+	LS013B7DH05,
+	LS018B7DH02,
+	LS027B7DH01,
+	LS027B7DH01A,
+	LS032B7DD02,
+	LS044Q7DH01,
+};
+
+enum sharp_memory_vcom_mode {
+	SHARP_MEMORY_SOFTWARE_VCOM,
+	SHARP_MEMORY_EXTERNAL_VCOM,
+	SHARP_MEMORY_PWM_VCOM
+};
+
+struct sharp_memory_device {
+	struct drm_device drm;
+	struct spi_device *spi;
+
+	const struct drm_display_mode *mode;
+
+	struct drm_crtc crtc;
+	struct drm_plane plane;
+	struct drm_encoder encoder;
+	struct drm_connector connector;
+
+	struct gpio_desc *enable_gpio;
+
+	struct task_struct *sw_vcom_signal;
+	struct pwm_device *pwm_vcom_signal;
+
+	enum sharp_memory_vcom_mode vcom_mode;
+	u8 vcom;
+
+	u32 pitch;
+	u32 tx_buffer_size;
+	u8 *tx_buffer;
+
+	/* When vcom_mode == "software" a kthread is used to periodically send a
+	 * 'maintain display' message over spi. This mutex ensures tx_buffer access
+	 * and spi bus usage is synchronized in this case.
+	 */
+	struct mutex tx_mutex;
+};
+
+static inline int sharp_memory_spi_write(struct spi_device *spi, void *buf, size_t len)
+{
+	/* Reverse the bit order */
+	for (u8 *b = buf; b < ((u8 *)buf) + len; ++b)
+		*b = bitrev8(*b);
+
+	return spi_write(spi, buf, len);
+}
+
+static inline struct sharp_memory_device *drm_to_sharp_memory_device(struct drm_device *drm)
+{
+	return container_of(drm, struct sharp_memory_device, drm);
+}
+
+DEFINE_DRM_GEM_DMA_FOPS(sharp_memory_fops);
+
+static const struct drm_driver sharp_memory_drm_driver = {
+	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+	.fops			= &sharp_memory_fops,
+	DRM_GEM_DMA_DRIVER_OPS_VMAP,
+	.name			= "sharp_memory_display",
+	.desc			= "Sharp Display Memory LCD",
+	.date			= "20231129",
+	.major			= 1,
+	.minor			= 0,
+};
+
+static inline void sharp_memory_set_tx_buffer_mode(u8 *buffer, u8 mode, u8 vcom)
+{
+	*buffer = mode | (vcom << 1);
+}
+
+static inline void sharp_memory_set_tx_buffer_addresses(u8 *buffer,
+							struct drm_rect clip,
+							u32 pitch)
+{
+	for (u32 line = 0; line < clip.y2; ++line)
+		buffer[line * pitch] = line + 1;
+}
+
+static void sharp_memory_set_tx_buffer_data(u8 *buffer,
+					    struct drm_framebuffer *fb,
+					    struct drm_rect clip,
+					    u32 pitch,
+					    struct drm_format_conv_state *fmtcnv_state)
+{
+	int ret;
+	struct iosys_map dst, vmap;
+	struct drm_gem_dma_object *dma_obj = drm_fb_dma_get_gem_obj(fb, 0);
+
+	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
+	if (ret)
+		return;
+
+	iosys_map_set_vaddr(&dst, buffer);
+	iosys_map_set_vaddr(&vmap, dma_obj->vaddr);
+
+	drm_fb_xrgb8888_to_mono(&dst, &pitch, &vmap, fb, &clip, fmtcnv_state);
+
+	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
+}
+
+static int sharp_memory_update_display(struct sharp_memory_device *smd,
+				       struct drm_framebuffer *fb,
+				       struct drm_rect clip,
+				       struct drm_format_conv_state *fmtcnv_state)
+{
+	int ret;
+	u32 pitch = smd->pitch;
+	u8 vcom = smd->vcom;
+	u8 *tx_buffer = smd->tx_buffer;
+	u32 tx_buffer_size = smd->tx_buffer_size;
+
+	mutex_lock(&smd->tx_mutex);
+
+	/* Populate the transmit buffer with frame data */
+	sharp_memory_set_tx_buffer_mode(&tx_buffer[0],
+					SHARP_MEMORY_DISPLAY_UPDATE_MODE, vcom);
+	sharp_memory_set_tx_buffer_addresses(&tx_buffer[1], clip, pitch);
+	sharp_memory_set_tx_buffer_data(&tx_buffer[2], fb, clip, pitch, fmtcnv_state);
+
+	ret = sharp_memory_spi_write(smd->spi, tx_buffer, tx_buffer_size);
+
+	mutex_unlock(&smd->tx_mutex);
+
+	return ret;
+}
+
+static int sharp_memory_maintain_display(struct sharp_memory_device *smd)
+{
+	int ret;
+	u8 vcom = smd->vcom;
+	u8 *tx_buffer = smd->tx_buffer;
+
+	mutex_lock(&smd->tx_mutex);
+
+	sharp_memory_set_tx_buffer_mode(&tx_buffer[0], SHARP_MEMORY_DISPLAY_MAINTAIN_MODE, vcom);
+	tx_buffer[1] = 0; // Write dummy data
+	ret = sharp_memory_spi_write(smd->spi, tx_buffer, 2);
+
+	mutex_unlock(&smd->tx_mutex);
+
+	return ret;
+}
+
+static int sharp_memory_clear_display(struct sharp_memory_device *smd)
+{
+	int ret;
+	u8 vcom = smd->vcom;
+	u8 *tx_buffer = smd->tx_buffer;
+
+	mutex_lock(&smd->tx_mutex);
+
+	sharp_memory_set_tx_buffer_mode(&tx_buffer[0], SHARP_MEMORY_DISPLAY_CLEAR_MODE, vcom);
+	tx_buffer[1] = 0; // write dummy data
+	ret = sharp_memory_spi_write(smd->spi, tx_buffer, 2);
+
+	mutex_unlock(&smd->tx_mutex);
+
+	return ret;
+}
+
+static void sharp_memory_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect,
+				  struct drm_format_conv_state *fmtconv_state)
+{
+	struct drm_rect clip;
+	struct sharp_memory_device *smd = drm_to_sharp_memory_device(fb->dev);
+
+	/* Always update a full line regardless of what is dirty */
+	clip.x1 = 0;
+	clip.x2 = fb->width;
+	clip.y1 = rect->y1;
+	clip.y2 = rect->y2;
+
+	sharp_memory_update_display(smd, fb, clip, fmtconv_state);
+}
+
+static int sharp_memory_plane_atomic_check(struct drm_plane *plane,
+					   struct drm_atomic_state *state)
+{
+	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+	struct sharp_memory_device *smd;
+	struct drm_crtc_state *crtc_state;
+
+	smd = container_of(plane, struct sharp_memory_device, plane);
+	crtc_state = drm_atomic_get_new_crtc_state(state, &smd->crtc);
+
+	return drm_atomic_helper_check_plane_state(plane_state, crtc_state,
+						   DRM_PLANE_NO_SCALING,
+						   DRM_PLANE_NO_SCALING,
+						   false, false);
+}
+
+static void sharp_memory_plane_atomic_update(struct drm_plane *plane,
+					     struct drm_atomic_state *state)
+{
+	struct drm_plane_state *old_state = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_plane_state *plane_state = plane->state;
+	struct drm_format_conv_state fmtcnv_state = DRM_FORMAT_CONV_STATE_INIT;
+	struct sharp_memory_device *smd;
+	struct drm_rect rect;
+
+	smd = container_of(plane, struct sharp_memory_device, plane);
+	if (!smd->crtc.state->active)
+		return;
+
+	if (drm_atomic_helper_damage_merged(old_state, plane_state, &rect))
+		sharp_memory_fb_dirty(plane_state->fb, &rect, &fmtcnv_state);
+
+	drm_format_conv_state_release(&fmtcnv_state);
+}
+
+static const struct drm_plane_helper_funcs sharp_memory_plane_helper_funcs = {
+	.prepare_fb = drm_gem_plane_helper_prepare_fb,
+	.atomic_check = sharp_memory_plane_atomic_check,
+	.atomic_update = sharp_memory_plane_atomic_update,
+};
+
+static bool sharp_memory_format_mod_supported(struct drm_plane *plane,
+					      u32 format,
+					      u64 modifier)
+{
+	return modifier == DRM_FORMAT_MOD_LINEAR;
+}
+
+static const struct drm_plane_funcs sharp_memory_plane_funcs = {
+	.update_plane = drm_atomic_helper_update_plane,
+	.disable_plane = drm_atomic_helper_disable_plane,
+	.destroy = drm_plane_cleanup,
+	.reset = drm_atomic_helper_plane_reset,
+	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
+	.format_mod_supported = sharp_memory_format_mod_supported,
+};
+
+static enum drm_mode_status sharp_memory_crtc_mode_valid(struct drm_crtc *crtc,
+							 const struct drm_display_mode *mode)
+{
+	struct sharp_memory_device *smd = drm_to_sharp_memory_device(crtc->dev);
+
+	return drm_crtc_helper_mode_valid_fixed(crtc, mode, smd->mode);
+}
+
+static int sharp_memory_crtc_check(struct drm_crtc *crtc,
+				   struct drm_atomic_state *state)
+{
+	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
+	int ret;
+
+	if (!crtc_state->enable)
+		goto out;
+
+	ret = drm_atomic_helper_check_crtc_primary_plane(crtc_state);
+	if (ret)
+		return ret;
+
+out:
+	return drm_atomic_add_affected_planes(state, crtc);
+}
+
+static int sharp_memory_sw_vcom_signal_thread(void *data)
+{
+	struct sharp_memory_device *smd = data;
+
+	while (!kthread_should_stop()) {
+		smd->vcom ^= 1; // Toggle vcom
+		sharp_memory_maintain_display(smd);
+		msleep(1000);
+	}
+
+	return 0;
+}
+
+static void sharp_memory_crtc_enable(struct drm_crtc *crtc,
+				     struct drm_atomic_state *state)
+{
+	struct pwm_state pwm_state;
+	struct sharp_memory_device *smd = drm_to_sharp_memory_device(crtc->dev);
+
+	sharp_memory_clear_display(smd);
+
+	if (smd->enable_gpio)
+		gpiod_set_value(smd->enable_gpio, 1);
+
+	switch (smd->vcom_mode) {
+	case SHARP_MEMORY_SOFTWARE_VCOM:
+		smd->sw_vcom_signal = kthread_run(sharp_memory_sw_vcom_signal_thread,
+						  smd, "sw_vcom_signal");
+		break;
+
+	case SHARP_MEMORY_EXTERNAL_VCOM:
+		break;
+
+	case SHARP_MEMORY_PWM_VCOM:
+		pwm_init_state(smd->pwm_vcom_signal, &pwm_state);
+		pwm_set_relative_duty_cycle(&pwm_state, 1, 10);
+		pwm_state.enabled = true;
+		pwm_apply_might_sleep(smd->pwm_vcom_signal, &pwm_state);
+		break;
+	}
+}
+
+static void sharp_memory_crtc_disable(struct drm_crtc *crtc,
+				      struct drm_atomic_state *state)
+{
+	struct sharp_memory_device *smd = drm_to_sharp_memory_device(crtc->dev);
+
+	sharp_memory_clear_display(smd);
+
+	if (smd->enable_gpio)
+		gpiod_set_value(smd->enable_gpio, 0);
+
+	switch (smd->vcom_mode) {
+	case SHARP_MEMORY_SOFTWARE_VCOM:
+		kthread_stop(smd->sw_vcom_signal);
+		break;
+
+	case SHARP_MEMORY_EXTERNAL_VCOM:
+		break;
+
+	case SHARP_MEMORY_PWM_VCOM:
+		pwm_disable(smd->pwm_vcom_signal);
+		break;
+	}
+}
+
+static const struct drm_crtc_helper_funcs sharp_memory_crtc_helper_funcs = {
+	.mode_valid = sharp_memory_crtc_mode_valid,
+	.atomic_check = sharp_memory_crtc_check,
+	.atomic_enable = sharp_memory_crtc_enable,
+	.atomic_disable = sharp_memory_crtc_disable,
+};
+
+static const struct drm_crtc_funcs sharp_memory_crtc_funcs = {
+	.reset = drm_atomic_helper_crtc_reset,
+	.destroy = drm_crtc_cleanup,
+	.set_config = drm_atomic_helper_set_config,
+	.page_flip = drm_atomic_helper_page_flip,
+	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+};
+
+static const struct drm_encoder_funcs sharp_memory_encoder_funcs = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static int sharp_memory_connector_get_modes(struct drm_connector *connector)
+{
+	struct sharp_memory_device *smd = drm_to_sharp_memory_device(connector->dev);
+
+	return drm_connector_helper_get_modes_fixed(connector, smd->mode);
+}
+
+static const struct drm_connector_helper_funcs sharp_memory_connector_hfuncs = {
+	.get_modes = sharp_memory_connector_get_modes,
+};
+
+static const struct drm_connector_funcs sharp_memory_connector_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+
+};
+
+static const struct drm_mode_config_funcs sharp_memory_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static const struct drm_display_mode sharp_memory_ls010b7dh04_mode = {
+	DRM_SIMPLE_MODE(128, 128, 18, 18),
+};
+
+static const struct drm_display_mode sharp_memory_ls011b7dh03_mode = {
+	DRM_SIMPLE_MODE(160, 68, 25, 10),
+};
+
+static const struct drm_display_mode sharp_memory_ls012b7dd01_mode = {
+	DRM_SIMPLE_MODE(184, 38, 29, 6),
+};
+
+static const struct drm_display_mode sharp_memory_ls013b7dh03_mode = {
+	DRM_SIMPLE_MODE(128, 128, 23, 23),
+};
+
+static const struct drm_display_mode sharp_memory_ls013b7dh05_mode = {
+	DRM_SIMPLE_MODE(144, 168, 20, 24),
+};
+
+static const struct drm_display_mode sharp_memory_ls018b7dh02_mode = {
+	DRM_SIMPLE_MODE(230, 303, 27, 36),
+};
+
+static const struct drm_display_mode sharp_memory_ls027b7dh01_mode = {
+	DRM_SIMPLE_MODE(400, 240, 58, 35),
+};
+
+static const struct drm_display_mode sharp_memory_ls032b7dd02_mode = {
+	DRM_SIMPLE_MODE(336, 536, 42, 68),
+};
+
+static const struct drm_display_mode sharp_memory_ls044q7dh01_mode = {
+	DRM_SIMPLE_MODE(320, 240, 89, 67),
+};
+
+static const struct spi_device_id sharp_memory_ids[] = {
+	{"ls010b7dh04", (kernel_ulong_t)&sharp_memory_ls010b7dh04_mode},
+	{"ls011b7dh03", (kernel_ulong_t)&sharp_memory_ls011b7dh03_mode},
+	{"ls012b7dd01", (kernel_ulong_t)&sharp_memory_ls012b7dd01_mode},
+	{"ls013b7dh03", (kernel_ulong_t)&sharp_memory_ls013b7dh03_mode},
+	{"ls013b7dh05", (kernel_ulong_t)&sharp_memory_ls013b7dh05_mode},
+	{"ls018b7dh02", (kernel_ulong_t)&sharp_memory_ls018b7dh02_mode},
+	{"ls027b7dh01", (kernel_ulong_t)&sharp_memory_ls027b7dh01_mode},
+	{"ls027b7dh01a", (kernel_ulong_t)&sharp_memory_ls027b7dh01_mode},
+	{"ls032b7dd02", (kernel_ulong_t)&sharp_memory_ls032b7dd02_mode},
+	{"ls044q7dh01", (kernel_ulong_t)&sharp_memory_ls044q7dh01_mode},
+	{},
+};
+MODULE_DEVICE_TABLE(spi, sharp_memory_ids);
+
+static const struct of_device_id sharp_memory_of_match[] = {
+	{.compatible = "sharp,ls010b7dh04", &sharp_memory_ls010b7dh04_mode},
+	{.compatible = "sharp,ls011b7dh03", &sharp_memory_ls011b7dh03_mode},
+	{.compatible = "sharp,ls012b7dd01", &sharp_memory_ls012b7dd01_mode},
+	{.compatible = "sharp,ls013b7dh03", &sharp_memory_ls013b7dh03_mode},
+	{.compatible = "sharp,ls013b7dh05", &sharp_memory_ls013b7dh05_mode},
+	{.compatible = "sharp,ls018b7dh02", &sharp_memory_ls018b7dh02_mode},
+	{.compatible = "sharp,ls027b7dh01", &sharp_memory_ls027b7dh01_mode},
+	{.compatible = "sharp,ls027b7dh01a", &sharp_memory_ls027b7dh01_mode},
+	{.compatible = "sharp,ls032b7dd02", &sharp_memory_ls032b7dd02_mode},
+	{.compatible = "sharp,ls044q7dh01", &sharp_memory_ls044q7dh01_mode},
+	{},
+};
+MODULE_DEVICE_TABLE(of, sharp_memory_of_match);
+
+static const u32 sharp_memory_formats[] = {
+	DRM_FORMAT_XRGB8888,
+};
+
+static int sharp_memory_pipe_init(struct drm_device *dev,
+				  struct sharp_memory_device *smd,
+				  const u32 *formats, unsigned int format_count,
+				  const u64 *format_modifiers)
+{
+	int ret;
+	struct drm_encoder *encoder = &smd->encoder;
+	struct drm_plane *plane = &smd->plane;
+	struct drm_crtc *crtc = &smd->crtc;
+	struct drm_connector *connector = &smd->connector;
+
+	drm_plane_helper_add(plane, &sharp_memory_plane_helper_funcs);
+	ret = drm_universal_plane_init(dev, plane, 0,
+				       &sharp_memory_plane_funcs,
+				       formats, format_count,
+				       format_modifiers,
+				       DRM_PLANE_TYPE_PRIMARY, NULL);
+	if (ret)
+		return ret;
+
+	drm_crtc_helper_add(crtc, &sharp_memory_crtc_helper_funcs);
+	ret = drm_crtc_init_with_planes(dev, crtc, plane, NULL,
+					&sharp_memory_crtc_funcs, NULL);
+	if (ret)
+		return ret;
+
+	encoder->possible_crtcs = drm_crtc_mask(crtc);
+	ret = drm_encoder_init(dev, encoder, &sharp_memory_encoder_funcs,
+			       DRM_MODE_ENCODER_NONE, NULL);
+	if (ret)
+		return ret;
+
+	ret = drm_connector_init(&smd->drm, &smd->connector,
+				 &sharp_memory_connector_funcs,
+				 DRM_MODE_CONNECTOR_SPI);
+	if (ret)
+		return ret;
+
+	drm_connector_helper_add(&smd->connector,
+				 &sharp_memory_connector_hfuncs);
+
+	return drm_connector_attach_encoder(connector, encoder);
+}
+
+static int sharp_memory_init_pwm_vcom_signal(struct sharp_memory_device *smd)
+{
+	struct pwm_state state;
+	struct device *dev = &smd->spi->dev;
+
+	smd->pwm_vcom_signal = devm_pwm_get(dev, NULL);
+	if (IS_ERR(smd->pwm_vcom_signal))
+		return dev_err_probe(dev, -EINVAL, "Could not get pwm device\n");
+
+	pwm_init_state(smd->pwm_vcom_signal, &state);
+	state.enabled = false;
+	pwm_apply_might_sleep(smd->pwm_vcom_signal, &state);
+
+	return 0;
+}
+
+static int sharp_memory_probe(struct spi_device *spi)
+{
+	int ret;
+	struct device *dev;
+	struct sharp_memory_device *smd;
+	struct drm_device *drm;
+	const char *vcom_mode_str;
+
+	dev = &spi->dev;
+
+	ret = spi_setup(spi);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to setup spi device\n");
+
+	if (!dev->coherent_dma_mask) {
+		ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to set dma mask\n");
+	}
+
+	smd = devm_drm_dev_alloc(dev, &sharp_memory_drm_driver,
+				 struct sharp_memory_device, drm);
+	if (!smd)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, smd);
+
+	smd->spi = spi;
+	drm = &smd->drm;
+	ret = drmm_mode_config_init(drm);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize drm config\n");
+
+	smd->enable_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH);
+	if (!smd->enable_gpio)
+		dev_warn(dev, "Enable gpio not defined\n");
+
+	/*
+	 * VCOM is a signal that prevents DC bias from being built up in
+	 * the panel resulting in pixels being forever stuck in one state.
+	 *
+	 * This driver supports three different methods to generate this
+	 * signal depending on EXTMODE pin:
+	 *
+	 * software (EXTMODE = L) - This mode uses a kthread to
+	 * periodically send a "maintain display" message to the display,
+	 * toggling the vcom bit on and off with each message
+	 *
+	 * external (EXTMODE = H) - This mode relies on an external
+	 * clock to generate the signal on the EXTCOMM pin
+	 *
+	 * pwm (EXTMODE = H) - This mode uses a pwm device to generate
+	 * the signal on the EXTCOMM pin
+	 *
+	 */
+	if (device_property_read_string(dev, "sharp,vcom-mode", &vcom_mode_str))
+		return dev_err_probe(dev, -EINVAL,
+				     "Unable to find sharp,vcom-mode node in device tree\n");
+
+	if (!strcmp("software", vcom_mode_str)) {
+		smd->vcom_mode = SHARP_MEMORY_SOFTWARE_VCOM;
+
+	} else if (!strcmp("external", vcom_mode_str)) {
+		smd->vcom_mode = SHARP_MEMORY_EXTERNAL_VCOM;
+
+	} else if (!strcmp("pwm", vcom_mode_str)) {
+		smd->vcom_mode = SHARP_MEMORY_PWM_VCOM;
+		ret = sharp_memory_init_pwm_vcom_signal(smd);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to initialize external COM signal\n");
+	} else {
+		return dev_err_probe(dev, -EINVAL, "Invalid value set for vcom-mode\n");
+	}
+
+	drm->mode_config.funcs = &sharp_memory_mode_config_funcs;
+	smd->mode = spi_get_device_match_data(spi);
+
+	smd->pitch = (SHARP_ADDR_PERIOD + smd->mode->hdisplay + SHARP_DUMMY_PERIOD) / 8;
+	smd->tx_buffer_size = (SHARP_MODE_PERIOD +
+			       (SHARP_ADDR_PERIOD + (smd->mode->hdisplay) + SHARP_DUMMY_PERIOD) *
+			       smd->mode->vdisplay) / 8;
+
+	smd->tx_buffer = devm_kzalloc(dev, smd->tx_buffer_size, GFP_KERNEL);
+	if (!smd->tx_buffer)
+		return -ENOMEM;
+
+	mutex_init(&smd->tx_mutex);
+
+	drm->mode_config.min_width = smd->mode->hdisplay;
+	drm->mode_config.max_width = smd->mode->hdisplay;
+	drm->mode_config.min_height = smd->mode->vdisplay;
+	drm->mode_config.max_height = smd->mode->vdisplay;
+
+	ret = sharp_memory_pipe_init(drm, smd, sharp_memory_formats,
+				     ARRAY_SIZE(sharp_memory_formats),
+				     NULL);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize display pipeline.\n");
+
+	drm_plane_enable_fb_damage_clips(&smd->plane);
+	drm_mode_config_reset(drm);
+
+	ret = drm_dev_register(drm, 0);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register drm device.\n");
+
+	drm_fbdev_dma_setup(drm, 0);
+
+	return 0;
+}
+
+static void sharp_memory_remove(struct spi_device *spi)
+{
+	struct sharp_memory_device *smd = spi_get_drvdata(spi);
+
+	drm_dev_unplug(&smd->drm);
+	drm_atomic_helper_shutdown(&smd->drm);
+}
+
+static struct spi_driver sharp_memory_spi_driver = {
+	.driver = {
+		.name = "sharp_memory",
+		.of_match_table = sharp_memory_of_match,
+	},
+	.probe = sharp_memory_probe,
+	.remove = sharp_memory_remove,
+	.id_table = sharp_memory_ids,
+};
+module_spi_driver(sharp_memory_spi_driver);
+
+MODULE_AUTHOR("Alex Lanzano <lanzano.alex@gmail.com>");
+MODULE_DESCRIPTION("SPI Protocol driver for the sharp_memory display");
+MODULE_LICENSE("GPL");
-- 
2.46.2

Re: [PATCH v8 0/2] Add driver for Sharp Memory LCD

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 1155 bytes --]

Hello,

On Tue, Oct 01, 2024 at 11:37:35PM -0400, Alex Lanzano wrote:
> This patch series add support for the monochrome Sharp Memory LCD
> panels. This series is based off of the work done by Mehdi Djait.
> 
> References:
> https://lore.kernel.org/dri-devel/71a9dbf4609dbba46026a31f60261830163a0b99.1701267411.git.mehdi.djait@bootlin.com/
> https://www.sharpsde.com/fileadmin/products/Displays/2016_SDE_App_Note_for_Memory_LCD_programming_V1.3.pdf
> 
> Co-developed-by: Mehdi Djait <mehdi.djait@bootlin.com>
> Signed-off-by: Mehdi Djait <mehdi.djait@bootlin.com>
> Signed-off-by: Alex Lanzano <lanzano.alex@gmail.com>
> ---
> Changes in v8:
> - Addressed review comments from Uwe
>     - Replace pwm_get_state with pwm_init_state
>     - Use pwm_set_relative_duty_cycle instead of manually setting period and duty cycle

You didn't explicitly mention that it's fine if the PWM doesn't emit the
inactive state when you call pwm_disable(). You're code should continue
to work if you drop all calls to pwm_disable().

Ideally you mention that in a code comment to make others reading your
code understand that.

Best regards
Uwe

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH v8 2/2] drm/tiny: Add driver for Sharp Memory LCD

[Markus Elfring]

…
> +++ b/drivers/gpu/drm/tiny/sharp-memory.c
> @@ -0,0 +1,681 @@
…
> +static int sharp_memory_maintain_display(struct sharp_memory_device *smd)
> +{
…
> +	u8 *tx_buffer = smd->tx_buffer;
> +
> +	mutex_lock(&smd->tx_mutex);
…
> +	mutex_unlock(&smd->tx_mutex);
> +
> +	return ret;
> +}
…

Will development interests grow for the application of a statement
like “guard(mutex)(&smd->tx_mutex);”?
https://elixir.bootlin.com/linux/v6.12-rc1/source/include/linux/mutex.h#L201

Regards,
Markus

Re: [PATCH v8 2/2] drm/tiny: Add driver for Sharp Memory LCD

[Greg KH]

On Wed, Oct 02, 2024 at 10:56:42AM +0200, Markus Elfring wrote:
> …
> > +++ b/drivers/gpu/drm/tiny/sharp-memory.c
> > @@ -0,0 +1,681 @@
> …
> > +static int sharp_memory_maintain_display(struct sharp_memory_device *smd)
> > +{
> …
> > +	u8 *tx_buffer = smd->tx_buffer;
> > +
> > +	mutex_lock(&smd->tx_mutex);
> …
> > +	mutex_unlock(&smd->tx_mutex);
> > +
> > +	return ret;
> > +}
> …
> 
> Will development interests grow for the application of a statement
> like “guard(mutex)(&smd->tx_mutex);”?
> https://elixir.bootlin.com/linux/v6.12-rc1/source/include/linux/mutex.h#L201


Hi,

This is the semi-friendly patch-bot of Greg Kroah-Hartman.

Markus, you seem to have sent a nonsensical or otherwise pointless
review comment to a patch submission on a Linux kernel developer mailing
list.  I strongly suggest that you not do this anymore.  Please do not
bother developers who are actively working to produce patches and
features with comments that, in the end, are a waste of time.

Patch submitter, please ignore Markus's suggestion; you do not need to
follow it at all.  The person/bot/AI that sent it is being ignored by
almost all Linux kernel maintainers for having a persistent pattern of
behavior of producing distracting and pointless commentary, and
inability to adapt to feedback.  Please feel free to also ignore emails
from them.

thanks,

greg k-h's patch email bot

Re: [PATCH v8 0/2] Add driver for Sharp Memory LCD

[Alex Lanzano]

On Wed, Oct 02, 2024 at 09:56:38AM GMT, Uwe Kleine-König wrote:
> Hello,
> 
> On Tue, Oct 01, 2024 at 11:37:35PM -0400, Alex Lanzano wrote:
> > This patch series add support for the monochrome Sharp Memory LCD
> > panels. This series is based off of the work done by Mehdi Djait.
> > 
> > References:
> > https://lore.kernel.org/dri-devel/71a9dbf4609dbba46026a31f60261830163a0b99.1701267411.git.mehdi.djait@bootlin.com/
> > https://www.sharpsde.com/fileadmin/products/Displays/2016_SDE_App_Note_for_Memory_LCD_programming_V1.3.pdf
> > 
> > Co-developed-by: Mehdi Djait <mehdi.djait@bootlin.com>
> > Signed-off-by: Mehdi Djait <mehdi.djait@bootlin.com>
> > Signed-off-by: Alex Lanzano <lanzano.alex@gmail.com>
> > ---
> > Changes in v8:
> > - Addressed review comments from Uwe
> >     - Replace pwm_get_state with pwm_init_state
> >     - Use pwm_set_relative_duty_cycle instead of manually setting period and duty cycle
> 
> You didn't explicitly mention that it's fine if the PWM doesn't emit the
> inactive state when you call pwm_disable(). You're code should continue
> to work if you drop all calls to pwm_disable().
> 
> Ideally you mention that in a code comment to make others reading your
> code understand that.

Sorry about that! The intent of the code is to stop the pwm from outputing
when the display is disabled since the signal is no longer needed. If
it's best to emit the inactive state rather than calling pwm_disable()
I'm fine with making that change.

Best regards,
Alex

Re: [PATCH v8 0/2] Add driver for Sharp Memory LCD

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 2154 bytes --]

Hello Alex,

On Wed, Oct 02, 2024 at 10:33:13PM -0400, Alex Lanzano wrote:
> On Wed, Oct 02, 2024 at 09:56:38AM GMT, Uwe Kleine-König wrote:
> > On Tue, Oct 01, 2024 at 11:37:35PM -0400, Alex Lanzano wrote:
> > > Changes in v8:
> > > - Addressed review comments from Uwe
> > >     - Replace pwm_get_state with pwm_init_state
> > >     - Use pwm_set_relative_duty_cycle instead of manually setting period and duty cycle
> > 
> > You didn't explicitly mention that it's fine if the PWM doesn't emit the
> > inactive state when you call pwm_disable(). You're code should continue
> > to work if you drop all calls to pwm_disable().
> > 
> > Ideally you mention that in a code comment to make others reading your
> > code understand that.
> 
> Sorry about that! The intent of the code is to stop the pwm from outputing
> when the display is disabled since the signal is no longer needed. If
> it's best to emit the inactive state rather than calling pwm_disable()
> I'm fine with making that change.

Calling pwm_disable() is best iff you don't care about the output any
more. If however you rely on it to emit the inactive level,
pwm_disable() is wrong. I don't know enough about your display to judge
from here.

The code to disable the display looks (simplified) as follows:

	if (smd->enable_gpio)
		gpiod_set_value(smd->enable_gpio, 0);

	pwm_disable(smd->pwm_vcom_signal);

so maybe the logic you need is:

	if (smd->enable_gpio) {
		gpiod_set_value(smd->enable_gpio, 0);

		/*
		 * In the presence of a GPIO to disable the display the
		 * behaviour of the PWM doesn't matter and we can
		 * just disable it.
		 */
		pwm_disable(smd->pwm_vcom_signal);
	} else {
		struct pwm_state state;

		/*
		 * However without a GPIO driving the display's output
		 * enable pin the PWM must emit the inactive level,
		 * which isn't guaranteed when calling pwm_disable(), so
		 * configure it for duty_cycle = 0.
		 */
		 pwm_init_state(smd->pwm_vcom_signal, &state);
		 state.duty_cycle = 0;
		 state.enabled = true;
		 pwm_apply_might_sleep(smd->pwm_vcom_signal, &state);
	}

?

Best regards
Uwe

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH v8 0/2] Add driver for Sharp Memory LCD

[Alex Lanzano]

On Thu, Oct 03, 2024 at 11:27:43AM GMT, Uwe Kleine-König wrote:
> Hello Alex,
> 
> On Wed, Oct 02, 2024 at 10:33:13PM -0400, Alex Lanzano wrote:
> > On Wed, Oct 02, 2024 at 09:56:38AM GMT, Uwe Kleine-König wrote:
> > > On Tue, Oct 01, 2024 at 11:37:35PM -0400, Alex Lanzano wrote:
> > > > Changes in v8:
> > > > - Addressed review comments from Uwe
> > > >     - Replace pwm_get_state with pwm_init_state
> > > >     - Use pwm_set_relative_duty_cycle instead of manually setting period and duty cycle
> > > 
> > > You didn't explicitly mention that it's fine if the PWM doesn't emit the
> > > inactive state when you call pwm_disable(). You're code should continue
> > > to work if you drop all calls to pwm_disable().
> > > 
> > > Ideally you mention that in a code comment to make others reading your
> > > code understand that.
> > 
> > Sorry about that! The intent of the code is to stop the pwm from outputing
> > when the display is disabled since the signal is no longer needed. If
> > it's best to emit the inactive state rather than calling pwm_disable()
> > I'm fine with making that change.
> 
> Calling pwm_disable() is best iff you don't care about the output any
> more. If however you rely on it to emit the inactive level,
> pwm_disable() is wrong. I don't know enough about your display to judge
> from here.
> 
> The code to disable the display looks (simplified) as follows:
> 
> 	if (smd->enable_gpio)
> 		gpiod_set_value(smd->enable_gpio, 0);
> 
> 	pwm_disable(smd->pwm_vcom_signal);
> 
> so maybe the logic you need is:
> 
> 	if (smd->enable_gpio) {
> 		gpiod_set_value(smd->enable_gpio, 0);
> 
> 		/*
> 		 * In the presence of a GPIO to disable the display the
> 		 * behaviour of the PWM doesn't matter and we can
> 		 * just disable it.
> 		 */
> 		pwm_disable(smd->pwm_vcom_signal);
> 	} else {
> 		struct pwm_state state;
> 
> 		/*
> 		 * However without a GPIO driving the display's output
> 		 * enable pin the PWM must emit the inactive level,
> 		 * which isn't guaranteed when calling pwm_disable(), so
> 		 * configure it for duty_cycle = 0.
> 		 */
> 		 pwm_init_state(smd->pwm_vcom_signal, &state);
> 		 state.duty_cycle = 0;
> 		 state.enabled = true;
> 		 pwm_apply_might_sleep(smd->pwm_vcom_signal, &state);
> 	}
> 

Ahh, understood. I looked over the datasheet again. It looks like in the
case where no enable gpio pin is defined we'll need to keep the pwm pulsing
since display hardware would still be enabled.

I'll fix this up in the disable and probe functions.

Best regards,
Alex