Message-ID: <CAA8EJpowdjcN8KzGRVLrGx8L8Fi5Drs-C62VZKd5VbmDHsCg+Q@mail.gmail.com>
Date: Sat, 30 Mar 2024 16:37:08 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Marijn Suijten <marijn.suijten@...ainline.org>
Cc: Sumit Semwal <sumit.semwal@...aro.org>, Caleb Connolly <caleb.connolly@...aro.org>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Sam Ravnborg <sam@...nborg.org>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
	Vinod Koul <vkoul@...nel.org>, Caleb Connolly <caleb@...nolly.tech>
Subject: Re: [PATCH 3/3] drm: panel: Add LG sw43408 panel driver

On Sat, 30 Mar 2024 at 12:27, Marijn Suijten
<marijn.suijten@...ainline.org> wrote:
>
> On 2024-03-30 05:59:30, Dmitry Baryshkov wrote:
> > From: Sumit Semwal <sumit.semwal@...aro.org>
> >
> > LG SW43408 is 1080x2160, 4-lane MIPI-DSI panel, used in some Pixel3
> > phones.
> >
> > Whatever init sequence we have for this panel isn't capable of
> > initialising it completely, toggling the reset gpio ever causes the
> > panel to die. Until this is resolved we avoid resetting the panel. The
>
> Are you sure it is avoided?  This patch seems to be toggling reset_gpio in
> sw43408_prepare()?
>
> > disable/unprepare functions only put the panel to sleep mode and
> > disable the backlight.
> >
> > Signed-off-by: Sumit Semwal <sumit.semwal@...aro.org>
> > [vinod: Add DSC support]
> > Signed-off-by: Vinod Koul <vkoul@...nel.org>
> > [caleb: cleanup and support turning off the panel]
> > Signed-off-by: Caleb Connolly <caleb@...nolly.tech>
> > [DB: partially rewrote the driver and fixed DSC programming]
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > ---
> >  MAINTAINERS                              |   8 +
> >  drivers/gpu/drm/panel/Kconfig            |  11 ++
> >  drivers/gpu/drm/panel/Makefile           |   1 +
> >  drivers/gpu/drm/panel/panel-lg-sw43408.c | 322 +++++++++++++++++++++++++++++++
> >  4 files changed, 342 insertions(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 4b511a55101c..f4cf7ee97376 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -6755,6 +6755,14 @@ S:     Maintained
> >  F:   Documentation/devicetree/bindings/display/panel/jadard,jd9365da-h3.yaml
> >  F:   drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> >
> > +DRM DRIVER FOR LG SW43408 PANELS
> > +M:   Sumit Semwal <sumit.semwal@...aro.org>
> > +M:   Caleb Connolly <caleb.connolly@...aro.org>
> > +S:   Maintained
> > +T:   git git://anongit.freedesktop.org/drm/drm-misc
> > +F:   Documentation/devicetree/bindings/display/panel/lg,sw43408.yaml
> > +F:   drivers/gpu/drm/panel/panel-lg-sw43408.c
> > +
> >  DRM DRIVER FOR LOGICVC DISPLAY CONTROLLER
> >  M:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> >  S:   Supported
> > diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> > index d037b3b8b999..f94c702735cb 100644
> > --- a/drivers/gpu/drm/panel/Kconfig
> > +++ b/drivers/gpu/drm/panel/Kconfig
> > @@ -335,6 +335,17 @@ config DRM_PANEL_LG_LG4573
> >         Say Y here if you want to enable support for LG4573 RGB panel.
> >         To compile this driver as a module, choose M here.
> >
> > +config DRM_PANEL_LG_SW43408
> > +     tristate "LG SW43408 panel"
> > +     depends on OF
> > +     depends on DRM_MIPI_DSI
> > +     depends on BACKLIGHT_CLASS_DEVICE
> > +     help
> > +       Say Y here if you want to enable support for LG sw43408 panel.
> > +       The panel has a 1080x2160 resolution and uses
> > +       24 bit RGB per pixel. It provides a MIPI DSI interface to
> > +       the host and has a built-in LED backlight.
> > +
> >  config DRM_PANEL_MAGNACHIP_D53E6EA8966
> >       tristate "Magnachip D53E6EA8966 DSI panel"
> >       depends on OF && SPI
> > diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> > index f156d7fa0bcc..a75687d13caf 100644
> > --- a/drivers/gpu/drm/panel/Makefile
> > +++ b/drivers/gpu/drm/panel/Makefile
> > @@ -34,6 +34,7 @@ obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK050H3146W) += panel-leadtek-ltk050h3146w.o
> >  obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += panel-leadtek-ltk500hd1829.o
> >  obj-$(CONFIG_DRM_PANEL_LG_LB035Q02) += panel-lg-lb035q02.o
> >  obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
> > +obj-$(CONFIG_DRM_PANEL_LG_SW43408) += panel-lg-sw43408.o
> >  obj-$(CONFIG_DRM_PANEL_MAGNACHIP_D53E6EA8966) += panel-magnachip-d53e6ea8966.o
> >  obj-$(CONFIG_DRM_PANEL_NEC_NL8048HL11) += panel-nec-nl8048hl11.o
> >  obj-$(CONFIG_DRM_PANEL_NEWVISION_NV3051D) += panel-newvision-nv3051d.o
> > diff --git a/drivers/gpu/drm/panel/panel-lg-sw43408.c b/drivers/gpu/drm/panel/panel-lg-sw43408.c
> > new file mode 100644
> > index 000000000000..365d25e14d54
> > --- /dev/null
> > +++ b/drivers/gpu/drm/panel/panel-lg-sw43408.c
> > @@ -0,0 +1,322 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2019-2024 Linaro Ltd
> > + * Author: Sumit Semwal <sumit.semwal@...aro.org>
> > + *    Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > + */
> > +
> > +#include <linux/backlight.h>
> > +#include <linux/delay.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/regulator/consumer.h>
> > +
> > +#include <video/mipi_display.h>
> > +
> > +#include <drm/drm_mipi_dsi.h>
> > +#include <drm/drm_panel.h>
> > +#include <drm/drm_probe_helper.h>
> > +#include <drm/display/drm_dsc.h>
> > +#include <drm/display/drm_dsc_helper.h>
> > +
> > +#define NUM_SUPPLIES 2
> > +
> > +struct sw43408_panel {
> > +     struct drm_panel base;
> > +     struct mipi_dsi_device *link;
> > +
> > +     const struct drm_display_mode *mode;
> > +
> > +     struct regulator_bulk_data supplies[NUM_SUPPLIES];
> > +
> > +     struct gpio_desc *reset_gpio;
> > +};
> > +
> > +static inline struct sw43408_panel *to_panel_info(struct drm_panel *panel)
> > +{
> > +     return container_of(panel, struct sw43408_panel, base);
> > +}
> > +
> > +static int sw43408_unprepare(struct drm_panel *panel)
> > +{
> > +     struct sw43408_panel *ctx = to_panel_info(panel);
> > +     int ret;
> > +
> > +     ret = mipi_dsi_dcs_set_display_off(ctx->link);
> > +     if (ret < 0)
> > +             dev_err(panel->dev, "set_display_off cmd failed ret = %d\n", ret);
> > +
> > +     ret = mipi_dsi_dcs_enter_sleep_mode(ctx->link);
> > +     if (ret < 0)
> > +             dev_err(panel->dev, "enter_sleep cmd failed ret = %d\n", ret);
> > +
> > +     msleep(100);
> > +
> > +     gpiod_set_value(ctx->reset_gpio, 1);
> > +
> > +     return regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
> > +}
> > +
> > +static int sw43408_program(struct drm_panel *panel)
> > +{
> > +     struct sw43408_panel *ctx = to_panel_info(panel);
> > +     struct drm_dsc_picture_parameter_set pps;
> > +     u8 dsc_en = 0x11;
>
> Yeah, this is completely strange. Bit 0, 0x1, is to enable DSC which is
> normal. 0x10 however, which is bit 4, selects PPS table 2.  Do you ever set
> pps_identifier in struct drm_dsc_picture_parameter_set to 2?  Or is the table
> that you send below bogus and/or not used?  Maybe the Driver IC on the other
> end of the DSI link has a default PPS table with identifier 2 that works out of
> the box?

Note, MIPI standard also requires two bytes argument. I suspect that
LG didn't fully follow the standard here.
Basically that's the reason why I went for the _raw function instead
of adding PPS and codec arguments to the existing function.

>
> > +     mipi_dsi_dcs_write_seq(ctx->link, MIPI_DCS_SET_GAMMA_CURVE, 0x02);
> > +
> > +     mipi_dsi_dcs_set_tear_on(ctx->link, MIPI_DSI_DCS_TEAR_MODE_VBLANK);
> > +
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0x53, 0x0c, 0x30);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0x55, 0x00, 0x70, 0xdf, 0x00, 0x70, 0xdf);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xf7, 0x01, 0x49, 0x0c);
> > +
> > +     mipi_dsi_dcs_exit_sleep_mode(ctx->link);
> > +
> > +     msleep(135);
> > +
> > +     mipi_dsi_compression_mode_raw(ctx->link, &dsc_en, 1);
>
> Even though I think we should change this function to describe the known
> bit layout of command 0x7 per the VESA DSI spec, for now replace 1 with
> sizeof(dsc_en)?

If dsc_en were an array, it would have been a proper thing. Maybe I
should change it to the array to remove confusion.

>
> > +
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xb0, 0xac);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xe5,
> > +                            0x00, 0x3a, 0x00, 0x3a, 0x00, 0x0e, 0x10);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xb5,
> > +                            0x75, 0x60, 0x2d, 0x5d, 0x80, 0x00, 0x0a, 0x0b,
> > +                            0x00, 0x05, 0x0b, 0x00, 0x80, 0x0d, 0x0e, 0x40,
> > +                            0x00, 0x0c, 0x00, 0x16, 0x00, 0xb8, 0x00, 0x80,
> > +                            0x0d, 0x0e, 0x40, 0x00, 0x0c, 0x00, 0x16, 0x00,
> > +                            0xb8, 0x00, 0x81, 0x00, 0x03, 0x03, 0x03, 0x01,
> > +                            0x01);
> > +     msleep(85);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xcd,
> > +                            0x00, 0x00, 0x00, 0x19, 0x19, 0x19, 0x19, 0x19,
> > +                            0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19,
> > +                            0x16, 0x16);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xcb, 0x80, 0x5c, 0x07, 0x03, 0x28);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xc0, 0x02, 0x02, 0x0f);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0x55, 0x04, 0x61, 0xdb, 0x04, 0x70, 0xdb);
> > +     mipi_dsi_dcs_write_seq(ctx->link, 0xb0, 0xca);
> > +
> > +     mipi_dsi_dcs_set_display_on(ctx->link);
>
> Any specific reason to not have the (un)blanking sequence in the enable/disable
> callbacks and leaving display configuration in (un)prepare?

We are back to the question on when it's fine to send the commands. I
think the current agreement is to send everything in the
prepare/unprepare, because of some strange hosts.

> > +     msleep(50);
> > +
> > +     ctx->link->mode_flags &= ~MIPI_DSI_MODE_LPM;
> > +
> > +     drm_dsc_pps_payload_pack(&pps, ctx->link->dsc);
> > +     mipi_dsi_picture_parameter_set(ctx->link, &pps);
>
> I'm always surprised why this is sent _after_ turning the display on (unblanking
> it).  Wouldn't that cause unnecessary corruption?

No idea. I followed the dowsntream command sequences here. Most likely
the panel is not fully on until it receives the full frame to be
displayed.

> > +
> > +     ctx->link->mode_flags |= MIPI_DSI_MODE_LPM;
> > +
> > +     return 0;
> > +}
> > +
> > +static int sw43408_prepare(struct drm_panel *panel)
> > +{
> > +     struct sw43408_panel *ctx = to_panel_info(panel);
> > +     int ret;
> > +
> > +     ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     usleep_range(5000, 6000);
> > +
> > +     gpiod_set_value(ctx->reset_gpio, 0);
> > +     usleep_range(9000, 10000);
> > +     gpiod_set_value(ctx->reset_gpio, 1);
> > +     usleep_range(1000, 2000);
> > +     gpiod_set_value(ctx->reset_gpio, 0);
> > +     usleep_range(9000, 10000);
> > +
> > +     ret = sw43408_program(panel);
> > +     if (ret)
> > +             goto poweroff;
> > +
> > +     return 0;
> > +
> > +poweroff:
> > +     gpiod_set_value(ctx->reset_gpio, 1);
> > +     regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
> > +     return ret;
> > +}
> > +
> > +static int sw43408_get_modes(struct drm_panel *panel,
> > +                           struct drm_connector *connector)
> > +{
> > +     struct sw43408_panel *ctx = to_panel_info(panel);
> > +
> > +     return drm_connector_helper_get_modes_fixed(connector, ctx->mode);
> > +}
> > +
> > +static int sw43408_backlight_update_status(struct backlight_device *bl)
> > +{
> > +     struct mipi_dsi_device *dsi = bl_get_data(bl);
> > +     uint16_t brightness = backlight_get_brightness(bl);
> > +
> > +     return mipi_dsi_dcs_set_display_brightness_large(dsi, brightness);
> > +}
> > +
> > +const struct backlight_ops sw43408_backlight_ops = {
> > +     .update_status = sw43408_backlight_update_status,
> > +};
> > +
> > +static int sw43408_backlight_init(struct sw43408_panel *ctx)
> > +{
> > +     struct device *dev = &ctx->link->dev;
> > +     const struct backlight_properties props = {
> > +             .type = BACKLIGHT_PLATFORM,
> > +             .brightness = 255,
> > +             .max_brightness = 255,
> > +     };
> > +
> > +     ctx->base.backlight = devm_backlight_device_register(dev, dev_name(dev), dev,
> > +                                                     ctx->link,
> > +                                                     &sw43408_backlight_ops,
> > +                                                     &props);
> > +
> > +     if (IS_ERR(ctx->base.backlight))
> > +             return dev_err_probe(dev, PTR_ERR(ctx->base.backlight),
> > +                                  "Failed to create backlight\n");
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct drm_panel_funcs sw43408_funcs = {
> > +     .unprepare = sw43408_unprepare,
> > +     .prepare = sw43408_prepare,
> > +     .get_modes = sw43408_get_modes,
> > +};
> > +
> > +static const struct drm_display_mode sw43408_default_mode = {
> > +     .clock = 152340,
> > +
> > +     .hdisplay = 1080,
> > +     .hsync_start = 1080 + 20,
> > +     .hsync_end = 1080 + 20 + 32,
> > +     .htotal = 1080 + 20 + 32 + 20,
> > +
> > +     .vdisplay = 2160,
> > +     .vsync_start = 2160 + 20,
> > +     .vsync_end = 2160 + 20 + 4,
> > +     .vtotal = 2160 + 20 + 4 + 20,
> > +
> > +     .width_mm = 62,
> > +     .height_mm = 124,
> > +
> > +     .type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
> > +};
> > +
> > +static const struct of_device_id sw43408_of_match[] = {
> > +     { .compatible = "lg,sw43408", .data = &sw43408_default_mode },
> > +     { /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, sw43408_of_match);
> > +
> > +static int sw43408_add(struct sw43408_panel *ctx)
> > +{
> > +     struct device *dev = &ctx->link->dev;
> > +     int ret;
> > +
> > +     ctx->supplies[0].supply = "vddi"; /* 1.88 V */
> > +     ctx->supplies[0].init_load_uA = 62000;
> > +     ctx->supplies[1].supply = "vpnl"; /* 3.0 V */
> > +     ctx->supplies[1].init_load_uA = 857000;
> > +
> > +     ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ctx->supplies),
> > +                                   ctx->supplies);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     ctx->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> > +     if (IS_ERR(ctx->reset_gpio)) {
> > +             dev_err(dev, "cannot get reset gpio %ld\n",
> > +                           PTR_ERR(ctx->reset_gpio));
> > +             return PTR_ERR(ctx->reset_gpio);
> > +     }
> > +
> > +     ret = sw43408_backlight_init(ctx);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     ctx->base.prepare_prev_first = true;
> > +
> > +     drm_panel_init(&ctx->base, dev, &sw43408_funcs, DRM_MODE_CONNECTOR_DSI);
> > +
> > +     drm_panel_add(&ctx->base);
> > +     return ret;
> > +}
> > +
> > +static int sw43408_probe(struct mipi_dsi_device *dsi)
> > +{
> > +     struct sw43408_panel *ctx;
> > +     struct drm_dsc_config *dsc;
> > +     int ret;
> > +
> > +     ctx = devm_kzalloc(&dsi->dev, sizeof(*ctx), GFP_KERNEL);
> > +     if (!ctx)
> > +             return -ENOMEM;
> > +
> > +     ctx->mode = of_device_get_match_data(&dsi->dev);
> > +     dsi->mode_flags = MIPI_DSI_MODE_LPM;
> > +     dsi->format = MIPI_DSI_FMT_RGB888;
> > +     dsi->lanes = 4;
> > +
> > +     ctx->link = dsi;
> > +     mipi_dsi_set_drvdata(dsi, ctx);
> > +
> > +     ret = sw43408_add(ctx);
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     /* The panel is DSC panel only, set the dsc params */
> > +     dsc = devm_kzalloc(&dsi->dev, sizeof(*dsc), GFP_KERNEL);
>
> We've recently decided to store struct drm_dsc_config in struct sw43408_panel
> and save on an extra allocation.
>
> > +     if (!dsc)
> > +             return -ENOMEM;
> > +
> > +     dsc->dsc_version_major = 0x1;
> > +     dsc->dsc_version_minor = 0x1;
> > +
> > +     dsc->slice_height = 16;
> > +     dsc->slice_width = 540;
> > +     dsc->slice_count = 2;
>
> Maybe incorporate with a comment that slice_count * slice_width == the width of
> the mode?

ack

>
> - Marijn
>
> > +     dsc->bits_per_component = 8;
> > +     dsc->bits_per_pixel = 8 << 4;
> > +     dsc->block_pred_enable = true;
> > +
> > +     dsi->dsc = dsc;
> > +
> > +     return mipi_dsi_attach(dsi);
> > +}
> > +
> > +static void sw43408_remove(struct mipi_dsi_device *dsi)
> > +{
> > +     struct sw43408_panel *ctx = mipi_dsi_get_drvdata(dsi);
> > +     int ret;
> > +
> > +     ret = sw43408_unprepare(&ctx->base);
> > +     if (ret < 0)
> > +             dev_err(&dsi->dev, "failed to unprepare panel: %d\n",
> > +                           ret);
> > +
> > +     ret = mipi_dsi_detach(dsi);
> > +     if (ret < 0)
> > +             dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", ret);
> > +
> > +     drm_panel_remove(&ctx->base);
> > +}
> > +
> > +static struct mipi_dsi_driver sw43408_driver = {
> > +     .driver = {
> > +             .name = "panel-lg-sw43408",
> > +             .of_match_table = sw43408_of_match,
> > +     },
> > +     .probe = sw43408_probe,
> > +     .remove = sw43408_remove,
> > +};
> > +module_mipi_dsi_driver(sw43408_driver);
> > +
> > +MODULE_AUTHOR("Sumit Semwal <sumit.semwal@...aro.org>");
> > +MODULE_DESCRIPTION("LG SW436408 MIPI-DSI LED panel");
> > +MODULE_LICENSE("GPL");
> >
> > --
> > 2.39.2
> >



-- 
With best wishes
Dmitry

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