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 at 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 at denx.de>
>> + *
>> + * 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 at samsung.com>
>> + *
>> + * 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
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
