Message-ID: <9d50bc4e-e747-47fa-03cf-4dbd33f778dd@quicinc.com>
Date:   Thu, 25 May 2023 15:28:46 -0700
From:   Jessica Zhang <quic_jesszhan@...cinc.com>
To:     Marijn Suijten <marijn.suijten@...ainline.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC:     Neil Armstrong <neil.armstrong@...aro.org>,
        <devicetree@...r.kernel.org>, Sam Ravnborg <sam@...nborg.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        "Rob Herring" <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Subject: Re: [PATCH 2/2] drm/panel: Add driver for Visionox r66451 panel



On 5/23/2023 1:33 PM, Jessica Zhang wrote:
> 
> 
> On 5/21/2023 3:28 AM, Marijn Suijten wrote:
>> On 2023-05-18 03:19:49, Dmitry Baryshkov wrote:
>>> On 16/05/2023 23:20, Jessica Zhang wrote:
>>>> Add support for the 1080x2340 Visionox R66451 AMOLED DSI panel that
>>>> comes with the Qualcomm HDK8350 display expansion pack.
>>>>
>>>> The panel enables display compression (DSC v1.2) by default.
>>>>
>>>> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
>>>> ---
>>>>    drivers/gpu/drm/panel/Kconfig                 |   8 +
>>>>    drivers/gpu/drm/panel/Makefile                |   1 +
>>>>    drivers/gpu/drm/panel/panel-visionox-r66451.c | 395 
>>>> ++++++++++++++++++++++++++
>>>>    3 files changed, 404 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/panel/Kconfig 
>>>> b/drivers/gpu/drm/panel/Kconfig
>>>> index 29cf5fa39ff2..9c2c36dbddf3 100644
>>>> --- a/drivers/gpu/drm/panel/Kconfig
>>>> +++ b/drivers/gpu/drm/panel/Kconfig
>>>> @@ -766,6 +766,14 @@ config DRM_PANEL_VISIONOX_VTDR6130
>>>>          Say Y here if you want to enable support for Visionox
>>>>          VTDR6130 1080x2400 AMOLED DSI panel.
>>>> +config DRM_PANEL_VISIONOX_R66451
>>>> +    tristate "Visionox R66451"
>>>> +    depends on OF
>>>> +    depends on DRM_MIPI_DSI
>>>> +    help
>>>> +      Say Y here if you want to enable support for Visionox
>>>> +      R66451 1080x2340 AMOLED DSI panel.
>>>> +
>>>>    config DRM_PANEL_WIDECHIPS_WS2401
>>>>        tristate "Widechips WS2401 DPI panel driver"
>>>>        depends on SPI && GPIOLIB
>>>> diff --git a/drivers/gpu/drm/panel/Makefile 
>>>> b/drivers/gpu/drm/panel/Makefile
>>>> index b3e8ba29edd3..e043a92ee676 100644
>>>> --- a/drivers/gpu/drm/panel/Makefile
>>>> +++ b/drivers/gpu/drm/panel/Makefile
>>>> @@ -78,5 +78,6 @@ obj-$(CONFIG_DRM_PANEL_TPO_TPG110) += 
>>>> panel-tpo-tpg110.o
>>>>    obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o
>>>>    obj-$(CONFIG_DRM_PANEL_VISIONOX_RM69299) += panel-visionox-rm69299.o
>>>>    obj-$(CONFIG_DRM_PANEL_VISIONOX_VTDR6130) += 
>>>> panel-visionox-vtdr6130.o
>>>> +obj-$(CONFIG_DRM_PANEL_VISIONOX_R66451) += panel-visionox-r66451.o
>>>>    obj-$(CONFIG_DRM_PANEL_WIDECHIPS_WS2401) += panel-widechips-ws2401.o
>>>>    obj-$(CONFIG_DRM_PANEL_XINPENG_XPP055C272) += 
>>>> panel-xinpeng-xpp055c272.o
>>>> diff --git a/drivers/gpu/drm/panel/panel-visionox-r66451.c 
>>>> b/drivers/gpu/drm/panel/panel-visionox-r66451.c
>>>> new file mode 100644
>>>> index 000000000000..e3648ead3e84
>>>> --- /dev/null
>>>> +++ b/drivers/gpu/drm/panel/panel-visionox-r66451.c
>>>> @@ -0,0 +1,395 @@
>>>> +//SPDX-License-Identifier: GPL-2.0-only
>>>> +//Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights 
>>>> reserved.
>>>> +
>>>> +#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 <drm/drm_mipi_dsi.h>
>>>> +#include <drm/drm_modes.h>
>>>> +#include <drm/drm_panel.h>
>>>> +#include <drm/display/drm_dsc.h>
>>>> +#include <drm/display/drm_dsc_helper.h>
>>>> +
>>>> +#include <video/mipi_display.h>
>>>> +
>>>> +struct visionox_r66451 {
>>>> +    struct drm_panel panel;
>>>> +    struct mipi_dsi_device *dsi;
>>>> +    struct gpio_desc *reset_gpio;
>>>> +    struct regulator_bulk_data supplies[2];
>>>> +    bool prepared, enabled;
>>>> +};
>>>> +
>>>> +static inline struct visionox_r66451 *to_visionox_r66451(struct 
>>>> drm_panel *panel)
>>>> +{
>>>> +    return container_of(panel, struct visionox_r66451, panel);
>>>> +}
>>>> +
>>>> +static void visionox_r66451_reset(struct visionox_r66451 *ctx)
>>>> +{
>>>> +    gpiod_set_value_cansleep(ctx->reset_gpio, 0);
>>>> +    usleep_range(10000, 10100);
>>>> +    gpiod_set_value_cansleep(ctx->reset_gpio, 1);
>>>> +    usleep_range(10000, 10100);
>>>> +    gpiod_set_value_cansleep(ctx->reset_gpio, 0);
>>>> +    usleep_range(10000, 10100);
>>>> +}
>>>> +
>>>> +static int visionox_r66451_on(struct visionox_r66451 *ctx)
>>>> +{
>>>> +    struct mipi_dsi_device *dsi = ctx->dsi;
>>>> +    struct device *dev = &dsi->dev;
>>>> +    int ret;
>>>> +
>>>> +    dsi->mode_flags |= MIPI_DSI_MODE_LPM;
>>>> +
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xb0, 0x00);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xc2,
>>>> +                   0x09, 0x24, 0x0c, 0x00, 0x00, 0x0c, 0x00, 0x00, 
>>>> 0x00,
>>>> +                   0x09, 0x3c);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xd7,
>>>> +                   0x00, 0xb9, 0x3c, 0x00, 0x40, 0x04, 0x00, 0xa0, 
>>>> 0x0a,
>>>> +                   0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x19,
>>>> +                   0x3c, 0x00, 0x40, 0x04, 0x00, 0xa0, 0x0a);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xb0, 0x80);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xde,
>>>> +                   0x40, 0x00, 0x18, 0x00, 0x18, 0x00, 0x18, 0x00, 
>>>> 0x18,
>>>> +                   0x10, 0x00, 0x18, 0x00, 0x18, 0x00, 0x18, 0x02, 
>>>> 0x00, 0x00);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xb0, 0x04);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xe8, 0x00, 0x02);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xe4, 0x00, 0x08);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xb0, 0x00);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xc4,
>>>> +                   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x00,
>>>> +                   0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x32);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xcf,
>>>> +                   0x64, 0x0b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x08,
>>>> +                   0x00, 0x0b, 0x77, 0x01, 0x01, 0x01, 0x01, 0x01, 
>>>> 0x01,
>>>> +                   0x02, 0x02, 0x02, 0x02, 0x02, 0x03);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xd3,
>>>> +                   0x45, 0x00, 0x00, 0x01, 0x13, 0x15, 0x00, 0x15, 
>>>> 0x07,
>>>> +                   0x0f, 0x77, 0x77, 0x77, 0x37, 0xb2, 0x11, 0x00, 
>>>> 0xa0,
>>>> +                   0x3c, 0x9c);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xd7,
>>>> +                   0x00, 0xb9, 0x34, 0x00, 0x40, 0x04, 0x00, 0xa0, 
>>>> 0x0a,
>>>> +                   0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x19,
>>>> +                   0x34, 0x00, 0x40, 0x04, 0x00, 0xa0, 0x0a);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xd8,
>>>> +                   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x00,
>>>> +                   0x3a, 0x00, 0x3a, 0x00, 0x3a, 0x00, 0x3a, 0x00, 
>>>> 0x3a,
>>>> +                   0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x00,
>>>> +                   0x00, 0x0a, 0x00, 0x0a, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x00,
>>>> +                   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x0a,
>>>> +                   0x00, 0x32, 0x00, 0x0a, 0x00, 0x22);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xdf,
>>>> +                   0x50, 0x42, 0x58, 0x81, 0x2d, 0x00, 0x00, 0x00, 
>>>> 0x00,
>>>> +                   0x00, 0x00, 0x6b, 0x00, 0x00, 0x00, 0x00, 0x00, 
>>>> 0x00,
>>>> +                   0x00, 0x00, 0x01, 0x0f, 0xff, 0xd4, 0x0e, 0x00, 
>>>> 0x00,
>>>> +                   0x00, 0x00, 0x00, 0x00, 0x0f, 0x53, 0xf1, 0x00, 
>>>> 0x00,
>>>> +                   0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xf7, 0x01);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xb0, 0x80);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xe4, 0x34, 0xb4, 0x00, 0x00, 0x00, 
>>>> 0x39, 0x04, 0x09, 0x34);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xe6, 0x00);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xb0, 0x04);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xdf, 0x50, 0x40);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xf3, 0x50, 0x00, 0x00, 0x00, 0x00);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xf2, 0x11);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xf3, 0x01, 0x00, 0x00, 0x00, 0x01);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xf4, 0x00, 0x02);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xf2, 0x19);
>>>> +    mipi_dsi_dcs_write_seq(dsi, 0xdf, 0x50, 0x42);
>>>> +    mipi_dsi_dcs_set_tear_on(dsi, MIPI_DSI_DCS_TEAR_MODE_VBLANK);
>>>> +    mipi_dsi_dcs_write_seq(dsi, MIPI_DCS_SET_COLUMN_ADDRESS, 0x00, 
>>>> 0x00, 0x04, 0x37);
>>>
>>> Please use mipi_dsi_dcs_set_column_address(dsi, 0, 1080 - 1);
>>>
>>>> +    mipi_dsi_dcs_write_seq(dsi, MIPI_DCS_SET_PAGE_ADDRESS, 0x00, 
>>>> 0x00, 0x09, 0x23);
>>>
>>> mipi_dsi_dcs_set_page_address(dsi, 0, 2340 - 1);
>>
>> Yes please, thanks for already pointing these two out.
>>
>>>
>>>> +
>>>> +    ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
>>>> +    if (ret < 0) {
>>>> +        dev_err(dev, "Failed to exit sleep mode: %d\n", ret);
>>>> +        return ret;
>>>> +    }
>>>> +    msleep(120);
>>>> +
>>>> +    ret = mipi_dsi_dcs_set_display_on(dsi);
>>>
>>> Should the mipi_dsi_dcs_set_display_on() (and maybe exit sleep mode) be
>>> a a part of _enable()? Correspondingly _off should IMO be a part of
>>> _disable callback().
>>>
>>>> +    if (ret < 0) {
>>>> +        dev_err(dev, "Failed on set display on: %d\n", ret);
>>>> +        return ret;
>>>> +    }
>>>> +    msleep(20);
>>>
>>>
>>> Do we need to add here the following line?
>>>
>>> dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
>>>
>>>
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int visionox_r66451_off(struct visionox_r66451 *ctx)
>>>> +{
>>>> +    struct mipi_dsi_device *dsi = ctx->dsi;
>>>> +    struct device *dev = &dsi->dev;
>>>> +    int ret;
>>>> +
>>>> +    dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
>>>> +
>>>> +    ret = mipi_dsi_dcs_set_display_off(dsi);
>>>> +    if (ret < 0) {
>>>> +        dev_err(dev, "Failed to set display off: %d\n", ret);
>>>> +        return ret;
>>>> +    }
>>>> +    msleep(20);
>>>> +
>>>> +    ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
>>>> +    if (ret < 0) {
>>>> +        dev_err(dev, "Failed to enter sleep mode: %d\n", ret);
>>>> +        return ret;
>>>> +    }
>>>> +    msleep(120);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int visionox_r66451_prepare(struct drm_panel *panel)
>>>> +{
>>>> +    struct visionox_r66451 *ctx = to_visionox_r66451(panel);
>>>> +    struct device *dev = &ctx->dsi->dev;
>>>> +    int ret;
>>>> +
>>>> +    if (ctx->prepared)
>>>> +        return 0;
>>>> +
>>>> +    ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies),
>>>> +                    ctx->supplies);
>>>> +    if (ret < 0)
>>>> +        return ret;
>>>> +
>>>> +    visionox_r66451_reset(ctx);
>>>> +
>>>> +    ret = visionox_r66451_on(ctx);
>>>> +    if (ret < 0) {
>>>> +        dev_err(dev, "Failed to initialize panel: %d\n", ret);
>>>> +        gpiod_set_value_cansleep(ctx->reset_gpio, 1);
>>>> +        regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), 
>>>> ctx->supplies);
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    ctx->prepared = true;
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int visionox_r66451_unprepare(struct drm_panel *panel)
>>>> +{
>>>> +    struct visionox_r66451 *ctx = to_visionox_r66451(panel);
>>>> +    struct device *dev = &ctx->dsi->dev;
>>>> +    int ret;
>>>> +
>>>> +    if (!ctx->prepared)
>>>> +        return 0;
>>>> +
>>>> +    ret = visionox_r66451_off(ctx);
>>>> +    if (ret < 0)
>>>> +        dev_err(dev, "Failed to un-initialize panel: %d\n", ret);
>>>> +
>>>> +    gpiod_set_value_cansleep(ctx->reset_gpio, 1);
>>>> +    regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
>>>> +
>>>> +    ctx->prepared = false;
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static const struct drm_display_mode visionox_r66451_mode = {
>>>> +    .clock = (1080 + 95 + 1 + 40) * (2340 + 25 + 1 + 4) * 120 / 1000,
>>>> +    .hdisplay = 1080,
>>>> +    .hsync_start = 1080 + 95,
>>>> +    .hsync_end = 1080 + 95 + 1,
>>>> +    .htotal = 1080 + 95 + 1 + 40,
>>>> +    .vdisplay = 2340,
>>>> +    .vsync_start = 2340 + 25,
>>>> +    .vsync_end = 2340 + 25 + 1,
>>>> +    .vtotal = 2340 + 25 + 1 + 4,
>>>> +    .width_mm = 0,
>>>> +    .height_mm = 0,
>>>
>>> Please provide real values here.
>>>
>>>> +};
>>>> +
>>>> +static int visionox_r66451_enable(struct drm_panel *panel)
>>>> +{
>>>> +    struct visionox_r66451 *ctx = to_visionox_r66451(panel);
>>>> +    struct mipi_dsi_device *dsi = ctx->dsi;
>>>> +    struct drm_dsc_picture_parameter_set pps;
>>>> +    int ret;
>>>> +
>>>> +    if (ctx->enabled)
>>>> +        return 0;
>>>> +
>>>> +    if (!dsi->dsc) {
>>>> +        dev_err(&dsi->dev, "DSC not attached to DSI\n");
>>>> +        return -ENODEV;
>>>> +    }
>>>> +
>>>> +    drm_dsc_pps_payload_pack(&pps, dsi->dsc);
>>>> +    ret = mipi_dsi_picture_parameter_set(dsi, &pps);
>>
>> This `ret` value is unused.
> 
> Hi Marijn,
> 
> Acked.
> 
>>
>> Do we also need to call mipi_dsi_compression_mode() to enable
>> compression? 
> 
>  From my understanding, DSC is enabled by default for this panel, so 
> it's not necessary to explicitly set it.
> 
>> This also selects PPS table 1 (which is supposedly the
>> default reset value, and the PPS that is uploaded by
>> mipi_dsi_picture_parameter_set()).  Note that it does set the algorithm
>> to "VESA DSC Standard 1.1" but i am unsure if it makes a difference
>> (docs for mipi_dsi_picture_parameter_set() say that it is "1.1" as well)
> 
> We noticed the same thing when trying to debug an unrelated panel issue. 
> FWIW, the raw PPS values being sent to the panel are correct and it's 
> not breaking DSC for us.
> 
>>
>>>> +
>>>> +    ctx->enabled = true;
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int visionox_r66451_disable(struct drm_panel *panel)
>>>> +{
>>>> +    struct visionox_r66451 *ctx = to_visionox_r66451(panel);
>>>> +
>>>> +    ctx->enabled = false;
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int visionox_r66451_get_modes(struct drm_panel *panel,
>>>> +                    struct drm_connector *connector)
>>>> +{
>>>> +    struct drm_display_mode *mode;
>>>> +
>>>> +    mode = drm_mode_duplicate(connector->dev, &visionox_r66451_mode);
>>>> +    if (!mode)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    drm_mode_set_name(mode);
>>>> +
>>>> +    mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
>>>> +    connector->display_info.width_mm = mode->width_mm;
>>>> +    connector->display_info.height_mm = mode->height_mm;
>>>> +    drm_mode_probed_add(connector, mode);
>>>
>>> Can we use drm_connector_helper_get_modes_fixed() instead?
>>
>> This does not set DRM_MODE_TYPE_DRIVER though; is that preferred?
>>
>>>> +
>>>> +    return 1;
>>>> +}
>>>> +
>>>> +static const struct drm_panel_funcs visionox_r66451_funcs = {
>>>> +    .prepare = visionox_r66451_prepare,
>>>> +    .unprepare = visionox_r66451_unprepare,
>>>> +    .get_modes = visionox_r66451_get_modes,
>>>> +    .enable = visionox_r66451_enable,
>>>> +    .disable = visionox_r66451_disable,
>>>> +};
>>>> +
>>>> +static int visionox_r66451_bl_update_status(struct backlight_device 
>>>> *bl)
>>>> +{
>>>> +    struct mipi_dsi_device *dsi = bl_get_data(bl);
>>>> +    u16 brightness = backlight_get_brightness(bl);
>>>> +
>>>> +    return mipi_dsi_dcs_set_display_brightness(dsi, 
>>>> cpu_to_le16(brightness));
>>>
>>> mipi_dsi_dcs_set_display_brightness() already converts the brightness,
>>> so you don't need cpu_to_le16 here.
>>
>> Tread carefully here: we've had the same issue and conversation on our
>> Sony panels where this extra inversion is required.
>> set_display_brightness() sends the bytes as little-endian to the panel
>> (and it even assumes little-endian in get_display_brightness()) but the
>> spec for 16-bit brightness values states that they have to be sent in
>> big-endian.  This is why c9d27c6be518b ("drm/mipi-dsi: Fix byte order of
>> 16-bit DCS set/get brightness") added
>> mipi_dsi_dcs_set_display_brightness_large().
>>
>> Jessica, if you need to have the endian swap here (should be very easy
>> to test with a real panel, but it should be given the max_brightness
>> value being over 8 bits) please switch to the _large() variant.
> 
> Got it, thanks for the heads up!

Hi Marijn,

Just wanted to update this thread -- I've checked the backlight 
brightness values in the sysfs and it matches the value being given in 
the panel driver (255), so I think it should be fine to use 
*_set_display_brightness() without the _large() variant.

Thanks,

Jessica Zhang

> 
>>
>>>> +}
>>>> +
>>>> +static const struct backlight_ops visionox_r66451_bl_ops = {
>>>> +    .update_status = visionox_r66451_bl_update_status,
>>
>> Should this implement get_brightness?
> 
> I don't believe so. As far as I know, get_brightness() is an optional op 
> for if the panel has a special HW readback for getting the brightness 
> value, and this panel doesn't have that. So the default behavior of 
> getting the current brightness property value should be fine.
> 
>>
>>>> +};
>>>> +
>>>> +static struct backlight_device *
>>>> +visionox_r66451_create_backlight(struct mipi_dsi_device *dsi)
>>>> +{
>>>> +    struct device *dev = &dsi->dev;
>>>> +    const struct backlight_properties props = {
>>>> +        .type = BACKLIGHT_RAW,
>>>> +        .brightness = 255,
>>>> +        .max_brightness = 4095,
>>>> +    };
>>>> +
>>>> +    return devm_backlight_device_register(dev, dev_name(dev), dev, 
>>>> dsi,
>>>> +                          &visionox_r66451_bl_ops, &props);
>>>> +}
>>>> +
>>>> +static int visionox_r66451_probe(struct mipi_dsi_device *dsi)
>>>> +{
>>>> +    struct device *dev = &dsi->dev;
>>>> +    struct visionox_r66451 *ctx;
>>>> +    struct drm_dsc_config *dsc;
>>>> +    int ret = 0;
>>>> +
>>>> +    ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>>>> +    if (!ctx)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    dsc = devm_kzalloc(dev, sizeof(*dsc), GFP_KERNEL);
>>>> +    if (!dsc)
>>>> +        return -ENOMEM;
>>>> +
>>>> +    /* Set DSC params */
>>>> +    dsc->dsc_version_major = 0x1;
>>>> +    dsc->dsc_version_minor = 0x2;
>>>> +
>>>> +    dsc->slice_height = 20;
>>>> +    dsc->slice_width = 540;
>>>> +    dsc->slice_count = 2;
>>>> +    dsc->bits_per_component = 8;
>>>> +    dsc->bits_per_pixel = 0x8 << 4;
>>
>> What's the 0x for?  bpc is also just "8" and not 0x8.
> 
> Is there a functional difference between 0x8 vs 8? I can drop the "0x" 
> if you prefer it as decimal instead of hex.
> 
> Thanks,
> 
> Jessica Zhang
> 
>>
>> - Marijn
>>
>>>> +    dsc->block_pred_enable = true;
>>>> +
>>>> +    dsi->dsc = dsc;
>>>> +
>>>> +    ctx->supplies[0].supply = "vddio";
>>>> +    ctx->supplies[1].supply = "vdd";
>>>> +
>>>> +    ret = devm_regulator_bulk_get(&dsi->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))
>>>> +        return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio), "Failed 
>>>> to get reset-gpios\n");
>>>> +
>>>> +    ctx->dsi = dsi;
>>>> +    mipi_dsi_set_drvdata(dsi, ctx);
>>>> +
>>>> +    dsi->lanes = 4;
>>>> +    dsi->format = MIPI_DSI_FMT_RGB888;
>>>> +    dsi->mode_flags = MIPI_DSI_MODE_LPM | 
>>>> MIPI_DSI_CLOCK_NON_CONTINUOUS;
>>>> +
>>>> +    drm_panel_init(&ctx->panel, dev, &visionox_r66451_funcs, 
>>>> DRM_MODE_CONNECTOR_DSI);
>>>> +    ctx->panel.backlight = visionox_r66451_create_backlight(dsi);
>>>> +    if (IS_ERR(ctx->panel.backlight))
>>>> +        return dev_err_probe(dev, PTR_ERR(ctx->panel.backlight),
>>>> +                "Failed to create backlight\n");
>>>> +
>>>> +    drm_panel_add(&ctx->panel);
>>>> +
>>>> +    ret = mipi_dsi_attach(dsi);
>>>> +    if (ret < 0) {
>>>> +        dev_err(dev, "Failed to attach to DSI host: %d\n", ret);
>>>> +        drm_panel_remove(&ctx->panel);
>>>> +    }
>>>> +
>>>> +    return ret;
>>>> +}
>>>> +
>>>> +static void visionox_r66451_remove(struct mipi_dsi_device *dsi)
>>>> +{
>>>> +    struct visionox_r66451 *ctx = mipi_dsi_get_drvdata(dsi);
>>>> +    int ret;
>>>> +
>>>> +    ret = mipi_dsi_detach(dsi);
>>>> +    if (ret < 0)
>>>> +        dev_err(&dsi->dev, "Failed to detach DSI host: %d\n", ret);
>>>> +
>>>> +    drm_panel_remove(&ctx->panel);
>>>> +}
>>>> +
>>>> +static const struct of_device_id visionox_r66451_of_match[] = {
>>>> +    {.compatible = "visionox,r66451"},
>>>> +    { /*sentinel*/ }
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, visionox_r66451_of_match);
>>>> +
>>>> +static struct mipi_dsi_driver visionox_r66451_driver = {
>>>> +    .probe = visionox_r66451_probe,
>>>> +    .remove = visionox_r66451_remove,
>>>> +    .driver = {
>>>> +        .name = "panel-visionox-r66451",
>>>> +        .of_match_table = visionox_r66451_of_match,
>>>> +    },
>>>> +};
>>>> +
>>>> +module_mipi_dsi_driver(visionox_r66451_driver);
>>>> +
>>>> +MODULE_AUTHOR("Jessica Zhang <quic_jesszhan@...cinc.com>");
>>>> +MODULE_DESCRIPTION("Panel driver for the Visionox R66451 AMOLED DSI 
>>>> panel");
>>>> +MODULE_LICENSE("GPL");
>>>>
>>>
>>> -- 
>>> With best wishes
>>> Dmitry
>>>

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