From: "Luca Weiss" <luca.weiss@fairphone.com> To: "Thomas Zimmermann" <tzimmermann@suse.de>, "Luca Weiss" <luca.weiss@fairphone.com>, "Neil Armstrong" <neil.armstrong@linaro.org>, "Jessica Zhang" <jesszhan0024@gmail.com>, "Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>, "Maxime Ripard" <mripard@kernel.org>, "David Airlie" <airlied@gmail.com>, "Simona Vetter" <simona@ffwll.ch>, "Rob Herring" <robh@kernel.org>, "Krzysztof Kozlowski" <krzk+dt@kernel.org>, "Conor Dooley" <conor+dt@kernel.org>, "Bjorn Andersson" <andersson@kernel.org>, "Konrad Dybcio" <konradybcio@kernel.org> Cc: <~postmarketos/upstreaming@lists.sr.ht>, <phone-devel@vger.kernel.org>, <dri-devel@lists.freedesktop.org>, <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <linux-arm-msm@vger.kernel.org> Subject: Re: [PATCH 2/4] drm/panel: Add driver for Novatek NT37705 panel Date: Fri, 15 May 2026 16:31:51 +0200 [thread overview] Message-ID: <DIJBNGDNXE0L.2I0H4PBDDODOP@fairphone.com> (raw) In-Reply-To: <c06623ba-b19c-471a-becb-2fafddb3583c@suse.de> On Fri May 8, 2026 at 10:06 AM CEST, Thomas Zimmermann wrote: > Hi > > Am 01.05.26 um 15:52 schrieb Luca Weiss: >> Add support for the 2484x1116 AMOLED panel from BOE (BJ631JHM-T71-D900) >> bundled with a NT37705 driver IC, as found on the Fairphone (Gen. 6) >> smartphone. >> >> The panel can also be configured in 10-bit (RGB101010) mode, however >> currently it's configured in 8-bit (RGB888) since there's some issues in >> the Qualcomm DPU driver when driving this panel in 10-bit. >> >> Signed-off-by: Luca Weiss <luca.weiss@fairphone.com> >> --- >> drivers/gpu/drm/panel/Kconfig | 11 + >> drivers/gpu/drm/panel/Makefile | 1 + >> drivers/gpu/drm/panel/panel-novatek-nt37705.c | 413 ++++++++++++++++++++++++++ >> 3 files changed, 425 insertions(+) >> >> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig >> index 979109c27b9b..59ab3f29d8ef 100644 >> --- a/drivers/gpu/drm/panel/Kconfig >> +++ b/drivers/gpu/drm/panel/Kconfig >> @@ -624,6 +624,17 @@ config DRM_PANEL_NOVATEK_NT37700F >> Say Y here if you want to enable support for Novatek NT37700F DSI >> panel module. The panel has a resolution of 1080x2160. >> >> +config DRM_PANEL_NOVATEK_NT37705 >> + tristate "Novatek NT37705-based DSI panel" >> + depends on OF >> + depends on DRM_MIPI_DSI >> + depends on BACKLIGHT_CLASS_DEVICE >> + select DRM_KMS_HELPER >> + help >> + Say Y here if you want to enable support for Novatek NT37705-based >> + display panels, such as the one found in the The Fairphone (Gen. 6) > > Duplicate 'the' Marketing really wanted to have it be "The Fairphone". Will change and make it saner. > >> + smartphone. >> + >> config DRM_PANEL_NOVATEK_NT37801 >> tristate "Novatek NT37801/NT37810 AMOLED DSI panel" >> depends on OF >> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile >> index 0d694acbfbb6..94639bc58ca8 100644 >> --- a/drivers/gpu/drm/panel/Makefile >> +++ b/drivers/gpu/drm/panel/Makefile >> @@ -61,6 +61,7 @@ obj-$(CONFIG_DRM_PANEL_NOVATEK_NT36523) += panel-novatek-nt36523.o >> obj-$(CONFIG_DRM_PANEL_NOVATEK_NT36672A) += panel-novatek-nt36672a.o >> obj-$(CONFIG_DRM_PANEL_NOVATEK_NT36672E) += panel-novatek-nt36672e.o >> obj-$(CONFIG_DRM_PANEL_NOVATEK_NT37700F) += panel-novatek-nt37700f.o >> +obj-$(CONFIG_DRM_PANEL_NOVATEK_NT37705) += panel-novatek-nt37705.o >> obj-$(CONFIG_DRM_PANEL_NOVATEK_NT37801) += panel-novatek-nt37801.o >> obj-$(CONFIG_DRM_PANEL_NOVATEK_NT39016) += panel-novatek-nt39016.o >> obj-$(CONFIG_DRM_PANEL_MANTIX_MLAF057WE51) += panel-mantix-mlaf057we51.o >> diff --git a/drivers/gpu/drm/panel/panel-novatek-nt37705.c b/drivers/gpu/drm/panel/panel-novatek-nt37705.c >> new file mode 100644 >> index 000000000000..27bd8072ccd1 >> --- /dev/null >> +++ b/drivers/gpu/drm/panel/panel-novatek-nt37705.c >> @@ -0,0 +1,413 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * Generated with linux-mdss-dsi-panel-driver-generator from vendor device tree. >> + * Copyright (c) 2026 Luca Weiss <luca.weiss@fairphone.com> >> + */ >> + >> +#include <linux/backlight.h> >> +#include <linux/delay.h> >> +#include <linux/gpio/consumer.h> >> +#include <linux/mod_devicetable.h> >> +#include <linux/module.h> >> +#include <linux/regulator/consumer.h> >> + >> +#include <video/mipi_display.h> >> + >> +#include <drm/display/drm_dsc.h> >> +#include <drm/display/drm_dsc_helper.h> > > IIRC this requires > > select DRM_DISPLAY_DSC_HELPER > > in the Kconfig. Maybe double-check. Will check. Always difficult to figure out the proper dependencies in a fully-featured defconfig build. > >> +#include <drm/drm_mipi_dsi.h> >> +#include <drm/drm_modes.h> >> +#include <drm/drm_panel.h> >> +#include <drm/drm_probe_helper.h> >> + >> +struct nt37705_panel { >> + struct drm_panel panel; >> + struct mipi_dsi_device *dsi; >> + struct drm_dsc_config dsc; >> + struct regulator_bulk_data *supplies; >> + struct gpio_desc *reset_gpio; >> +}; >> + >> +static const struct regulator_bulk_data nt37705_supplies[] = { >> + { .supply = "vddio" }, >> + { .supply = "dvdd" }, >> + { .supply = "vci" }, >> +}; >> + >> +static inline struct nt37705_panel *to_nt37705_panel(struct drm_panel *panel) >> +{ >> + return container_of_const(panel, struct nt37705_panel, panel); > > Either just use container_of or build something that respects the > input's const-ness. I really don't get what you mean here? Why is container_of_const() bad here? > >> +} >> + >> +static void nt37705_reset(struct nt37705_panel *ctx) >> +{ >> + gpiod_set_value_cansleep(ctx->reset_gpio, 0); >> + usleep_range(10000, 11000); >> + gpiod_set_value_cansleep(ctx->reset_gpio, 1); >> + usleep_range(5000, 6000); >> + gpiod_set_value_cansleep(ctx->reset_gpio, 0); >> + usleep_range(10000, 11000); >> +} >> + >> +static int nt37705_on(struct nt37705_panel *ctx) >> +{ >> + struct mipi_dsi_multi_context dsi_ctx = { .dsi = ctx->dsi }; >> + >> + ctx->dsi->mode_flags |= MIPI_DSI_MODE_LPM; >> + >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, >> + 0x55, 0xaa, 0x52, 0x08, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x1b); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, 0x18); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x1c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, >> + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, >> + 0x00, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x2c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x00, 0x01, 0x01, 0x01, 0x00, 0x05, 0x05, >> + 0x05, 0x00, 0x05, 0x05, 0x05, 0x00, 0x00, >> + 0x00, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x3c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x0b, >> + 0x0b, 0x00, 0x00, 0x0b, 0x0b, 0x00, 0x00, >> + 0x00, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x4c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, >> + 0x1d, 0x00, 0x00, 0x00, 0x1d, 0x00, 0x00, >> + 0x00, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x5c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, >> + 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, >> + 0x01, 0x01); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x6c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x0b, >> + 0x77, 0x77, 0x00, 0x00, 0x0b, 0x00, 0x1d, >> + 0x00, 0x1d); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x7c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x0b, >> + 0x77, 0x77, 0x00, 0x00, 0x0b, 0x00, 0x1d, >> + 0x00, 0x1d); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x8c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, >> + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, >> + 0x00, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x9c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x11, 0x11, 0x20, 0x02, 0x00, 0x03, 0x00, >> + 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0xa4); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, 0x00, 0xc0, 0x40, 0x08); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0xa8); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, >> + 0x22); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0xb0); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xba, >> + 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, >> + 0x22); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, >> + 0x55, 0xaa, 0x52, 0x08, 0x01); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x05); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc5, 0x15, 0x15, 0x15, 0xdd); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, >> + 0x55, 0xaa, 0x52, 0x08, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x0e); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb5, 0x32); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, >> + 0x55, 0xaa, 0x52, 0x00, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xff, 0xaa, 0x55, 0xa5, 0x80); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x19); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf2, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x1a); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf4, 0x55); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x11); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf8, 0x01, 0x7f); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x2d); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf8, 0x01, 0x20); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xff, 0xaa, 0x55, 0xa5, 0x81); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x05); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfe, 0x3c); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x02); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf9, 0x04); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x1e); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfb, 0x0f); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x0f); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf5, 0x20); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x0d); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfb, 0x80); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xff, 0xaa, 0x55, 0xa5, 0x83); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x12); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfe, 0x41); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x13); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfd, 0x21); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xff, 0xaa, 0x55, 0xa5, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x35); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, MIPI_DCS_WRITE_CONTROL_DISPLAY, >> + 0x20); >> + mipi_dsi_dcs_set_column_address_multi(&dsi_ctx, 0x0000, 0x045b); >> + mipi_dsi_dcs_set_page_address_multi(&dsi_ctx, 0x0000, 0x09b3); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, MIPI_DCS_SET_GAMMA_CURVE, 0x00); >> + mipi_dsi_dcs_set_display_brightness_multi(&dsi_ctx, 0xbb0d); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6f, 0x04); >> + mipi_dsi_dcs_set_display_brightness_multi(&dsi_ctx, 0xfe0f); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x81, 0x01, 0x19); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x03, 0x01); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x90, 0x03, 0x03); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x91, >> + 0x89, 0x28, 0x00, 0x0c, 0xd2, 0x00, 0x02, >> + 0x2f, 0x01, 0x18, 0x00, 0x07, 0x09, 0x75, >> + 0x08, 0x34, 0x10, 0xf0); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x2f, 0x02); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x5a, 0x01); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x2f, 0x30); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x6d, 0x00); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x11, 0x00); >> + mipi_dsi_msleep(&dsi_ctx, 120); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x29, 0x00); >> + mipi_dsi_msleep(&dsi_ctx, 22); >> + >> + return dsi_ctx.accum_err; >> +} >> + >> +static int nt37705_off(struct nt37705_panel *ctx) >> +{ >> + struct mipi_dsi_multi_context dsi_ctx = { .dsi = ctx->dsi }; >> + >> + ctx->dsi->mode_flags &= ~MIPI_DSI_MODE_LPM; >> + >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x28, 0x00); >> + mipi_dsi_msleep(&dsi_ctx, 20); >> + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x10, 0x00); >> + mipi_dsi_msleep(&dsi_ctx, 120); >> + >> + return dsi_ctx.accum_err; >> +} >> + >> +static int nt37705_prepare(struct drm_panel *panel) >> +{ >> + struct nt37705_panel *ctx = to_nt37705_panel(panel); >> + struct device *dev = &ctx->dsi->dev; >> + struct drm_dsc_picture_parameter_set pps; >> + int ret; >> + >> + ret = regulator_bulk_enable(ARRAY_SIZE(nt37705_supplies), ctx->supplies); >> + if (ret < 0) { > > Common style is to check for errors with > > if (ret) > > Here and everywhere else. At least for regulator_bulk_enable() "ret < 0" is actually more popular than just "ret". Kernel doc says "Return: 0 on success or a negative error number on failure." so a positive integer should in theory never happen so they're equivalent. (git grep -h -A2 regulator_bulk_enable | grep if | sed 's|^[ \t]\+||' | sed 's| {$||' | sort | uniq -c) Thanks for the review! Regards Luca