Re: [PATCH] drm/panel: add lg4573 driver
From: Heiko Schocher
Date: Mon Jun 08 2015 - 04:13:47 EST
Hello Thierry,
Am 05.06.2015 14:19, schrieb Thierry Reding:
On Wed, May 06, 2015 at 09:49:33AM +0200, Heiko Schocher wrote:
The patch adds LG4573 parallel RGB panel driver with SPI control interface.
The driver uses drm_panel framework.
This should be obvious by the location of the driver. Can you instead
provide information about the type or resolution of the panel?
.../devicetree/bindings/panel/lg,lg4573.txt | 42 +++
drivers/gpu/drm/panel/Kconfig | 8 +
drivers/gpu/drm/panel/Makefile | 1 +
drivers/gpu/drm/panel/panel-lg4573.c | 367 +++++++++++++++++++++
4 files changed, 418 insertions(+)
create mode 100644 Documentation/devicetree/bindings/panel/lg,lg4573.txt
create mode 100644 drivers/gpu/drm/panel/panel-lg4573.c
diff --git a/Documentation/devicetree/bindings/panel/lg,lg4573.txt b/Documentation/devicetree/bindings/panel/lg,lg4573.txt
new file mode 100644
index 0000000..55f495d
--- /dev/null
+++ b/Documentation/devicetree/bindings/panel/lg,lg4573.txt
@@ -0,0 +1,42 @@
+LG LG4573 TFT liquid crystal display with SPI control bus
Please capitalize "Liquid Crystal Display".
done.
+
+Required properties:
+ - compatible: "lg4573"
This is missing the vendor prefix.
fixed.
+ - reg: address of the panel on SPI bus
"on the"
fixed.
+ - display-timings: timings for the connected panel according to [1]
The timings are already implied by the compatible value, so there's no
need to list them in DT.
I look into it ... is there an example for a panel driver with fixed
timings? Should I do it like it is done in the
drivers/gpu/drm/panel/panel-simple.c driver?
+The panel must obey rules for SPI slave device specified in document [2].
+
+Optional properties:
+ - power-on-delay: delay after turning regulators on [ms]
How is this a board-specific property? I'd assume that the same panel
always requires the same delay. Perhaps if this is board-specific it
really should be in the corresponding regulator's
regulator-enable-ramp-delay? Then again the binding doesn't describe any
regulators, so what exactly is this delay used for?
I rework this, and drop it.
+
+[1]: Documentation/devicetree/bindings/video/display-timing.txt
+[2]: Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Example:
+
+ lcd_panel: display@0 {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ compatible = "lg,lg4573";
+ spi-max-frequency = <10000000>;
+ reset-gpios = <&gpio2 11 0>;
This isn't documented above.
removed.
+ reg = <0>;
+ power-on-delay = <10>;
+ display-timings {
+ 480x800p57 {
+ native-mode;
+ clock-frequency = <27000027>;
+ hactive = <480>;
+ vactive = <800>;
+ hfront-porch = <10>;
+ hback-porch = <59>;
+ hsync-len = <10>;
+ vback-porch = <15>;
+ vfront-porch = <15>;
+ vsync-len = <15>;
+ hsync-active = <1>;
+ vsync-active = <1>;
+ };
+ };
+ };
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 6d64c7b..29c3407 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -23,6 +23,14 @@ config DRM_PANEL_LD9040
depends on OF && SPI
select VIDEOMODE_HELPERS
+config DRM_PANEL_LG4573
+ tristate "LG4573 RGB/SPI panel"
I'd like to get into the habit of prefixing the panels with a vendor
prefix, so this should become something like:
config DRM_PANEL_LG_LG4573
tristate "LG LG4573 RGB/SPI panel"
I have a local patch that converts existing boards, so with this
conversion it'd fit right it.
done.
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index 4b2a043..715b95d 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -1,4 +1,5 @@
obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
obj-$(CONFIG_DRM_PANEL_LD9040) += panel-ld9040.o
+obj-$(CONFIG_DRM_PANEL_LG4573) += panel-lg4573.o
Similarly for filenames, this would become: panel-lg-lg4573.c
done.
obj-$(CONFIG_DRM_PANEL_S6E8AA0) += panel-s6e8aa0.o
obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
diff --git a/drivers/gpu/drm/panel/panel-lg4573.c b/drivers/gpu/drm/panel/panel-lg4573.c
new file mode 100644
index 0000000..9d5e5a5
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-lg4573.c
@@ -0,0 +1,367 @@
+/*
+ *
+ * Copyright (C) 2015 Heiko Schocher <hs@xxxxxxx>
+ *
+ * from:
+ * drivers/gpu/drm/panel/panel-ld9040.c
+ * ld9040 AMOLED LCD drm_panel driver.
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd
+ * Derived from drivers/video/backlight/ld9040.c
+ *
+ * Andrzej Hajda <a.hajda@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <drm/drmP.h>
+#include <drm/drm_panel.h>
+
+#include <linux/gpio/consumer.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <video/mipi_display.h>
+#include <video/of_videomode.h>
+#include <video/videomode.h>
+
+struct lg4573 {
+ struct device *dev;
+ struct drm_panel panel;
Might be a slight optimization to put panel first in the structure.
fixed.
+ u32 power_on_delay;
+ struct videomode vm;
+};
+
+static inline struct lg4573 *panel_to_lg4573(struct drm_panel *panel)
+{
+ return container_of(panel, struct lg4573, panel);
+}
+
+static int lg4573_spi_write_u16(struct lg4573 *ctx, u16 data)
+{
+ struct spi_device *spi = to_spi_device(ctx->dev);
+ struct spi_transfer xfer = {
+ .len = 2,
No need for this padding. A single space will do.
fixed.
+ };
+ struct spi_message msg;
+ u16 temp = htons(data);
htons() always has this association to network programming. Perhaps it'd
be better to use cpu_to_be16() here?
yep, fixed.
+
+ dev_dbg(ctx->dev, "writing data: %x\n", data);
+ xfer.tx_buf = &temp;
+ spi_message_init(&msg);
+ spi_message_add_tail(&xfer, &msg);
+
+ return spi_sync(spi, &msg);
+}
+
+static void lg4573_spi_write_u16_array(struct lg4573 *ctx, u16 *buff, int size)
size should be of type size_t. Or in this case it's really a count, so
perhaps rename to count and make it unsigned int.
+{
+ int idx;
Then this would become unsigned int as well. And a more idiomatic name
would be i.
+
+ for (idx = 0; idx < size; idx++)
+ lg4573_spi_write_u16(ctx, buff[idx]);
+}
You completely ignore errors.
reworked this function complete and added error checking everywhere.
+static void lg4573_display_on(struct lg4573 *ctx)
+{
+ static u16 sleep_out = 0x7011;
+ static u16 display_on = 0x7029;
These seem to be (0x70 << 8 | MIPI_DCS_EXIT_SLEEP) and (0x70 << 8 |
MIPI_DCS_SET_DISPLAY_ON). Perhaps that 0x70 just means it's followed by
a MIPI DCS command, so I'm thinking perhaps you should add a function
such as lg4573_spi_write_dcs() which only takes the DCS command to avoid
all the repetition.
done.
+
+ lg4573_spi_write_u16(ctx, sleep_out);
+ msleep(ctx->power_on_delay);
+ lg4573_spi_write_u16(ctx, display_on);
+}
This also ignores errors. And the post-regulator delay is used here but
I don't see any regulators being powered up. According to the MIPI DCS
specification there needs to be a delay of 5 ms after the EXIT_SLEEP
command and any other command (120 ms if the command is ENTER_SLEEP).
Perhaps that's what you're after here? It would mean that the delay is
not board-specific and hence doesn't belong in DT.
removed.
+static int lg4573_display_off(struct lg4573 *ctx)
+{
+ static u16 display_off = 0x7028;
+ static u16 sleep_in = 0x7010;
More standard DCS commands. Also unnecessary tab, it should be a single
space instead.
reworked.
+
+ lg4573_spi_write_u16(ctx, display_off);
+ msleep(ctx->power_on_delay);
+ lg4573_spi_write_u16(ctx, sleep_in);
+ return 0;
+}
Also it's weird that this function returns a value. It always returns 0
so there's no point, really. You should perhaps think about propagating
any errors from the SPI write.
Yes, reworked.
+
+static void lg4573_display_mode_settings(struct lg4573 *ctx)
+{
+ static u16 display_mode_settings[] = {
+ 0x703A,
[...]
+ 0x7200,
+ };
Please make use of the 78/80 columns. Also, I don't suppose it'd be
possible to obtain symbolic names for these magic numbers? More of the
same below.
Fixed ... I try to find out more about this magic numbers, but I
can;t promise it ...
+static void lg4573_init(struct lg4573 *ctx)
+{
+ dev_dbg(ctx->dev, "initializing LCD\n");
+
+ lg4573_display_mode_settings(ctx);
+ lg4573_power_settings(ctx);
+ lg4573_gamma_settings(ctx);
+}
+
+static int lg4573_power_on(struct lg4573 *ctx)
+{
+ msleep(ctx->power_on_delay);
+ lg4573_display_on(ctx);
+ return 0;
+}
+
+static int lg4573_disable(struct drm_panel *panel)
+{
+ struct lg4573 *ctx = panel_to_lg4573(panel);
+
+ return lg4573_display_off(ctx);
+}
+
+static int lg4573_enable(struct drm_panel *panel)
+{
+ struct lg4573 *ctx = panel_to_lg4573(panel);
+ int ret;
+
+ lg4573_init(ctx);
+
+ ret = lg4573_power_on(ctx);
+
+ return ret;
+}
I think these should all propagate errors.
fixed.
+static int lg4573_get_modes(struct drm_panel *panel)
+{
+ struct drm_connector *connector = panel->connector;
+ struct lg4573 *ctx = panel_to_lg4573(panel);
+ struct drm_display_mode *mode;
+
+ mode = drm_mode_create(connector->dev);
+ if (!mode) {
+ DRM_ERROR("failed to create a new display mode\n");
+ return 0;
+ }
+
+ drm_display_mode_from_videomode(&ctx->vm, mode);
+
+ mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+ drm_mode_probed_add(connector, mode);
+
+ return 1;
+}
You can either use a hard-coded mode or use display timings along with
the helpers to convert the timings to a default mode. No need to parse
the information from DT.
Ok... see question above, could I do it like it is done in the
panel-simple driver? Or is there another way?
+static const struct drm_panel_funcs lg4573_drm_funcs = {
+ .disable = lg4573_disable,
+ .enable = lg4573_enable,
+ .get_modes = lg4573_get_modes,
+};
+
+static int lg4573_parse_dt(struct lg4573 *ctx)
+{
+ struct device *dev = ctx->dev;
+ struct device_node *np = dev->of_node;
+ int ret;
+
+ ret = of_get_videomode(np, &ctx->vm, 0);
+ if (ret < 0)
+ return ret;
+
+ of_property_read_u32(np, "power-on-delay", &ctx->power_on_delay);
+
+ return 0;
+}
+
+static int lg4573_probe(struct spi_device *spi)
+{
+ struct device *dev = &spi->dev;
+ struct lg4573 *ctx;
+ int ret;
+
+ ctx = devm_kzalloc(dev, sizeof(struct lg4573), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ spi_set_drvdata(spi, ctx);
+ ctx->dev = dev;
+
+ ret = lg4573_parse_dt(ctx);
+ if (ret < 0)
+ return ret;
+
+ spi->bits_per_word = 8;
+ ret = spi_setup(spi);
+ if (ret < 0) {
+ dev_err(dev, "spi setup failed.\n");
You might want to include the error code in the message. Also "SPI".
done.
+static const struct of_device_id lg4573_of_match[] = {
+ { .compatible = "lg,lg4573" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, lg4573_of_match);
+
+static struct spi_driver lg4573_driver = {
+ .probe = lg4573_probe,
+ .remove = lg4573_remove,
+ .driver = {
+ .name = "lg4573",
+ .owner = THIS_MODULE,
+ .of_match_table = lg4573_of_match,
+ },
No need for the padding. It's not consistent anyway.
fixed.
Thanks!
bye,
Heiko
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