Re: [PATCH] drm/panel: Add JDI LT070ME05000 WUXGA DSI Panel

[Vinay Simha]

Thierry Reding,

Thanks for the review. Will address your reviews and resend the patches.

On Wed, Apr 13, 2016 at 7:19 PM, Thierry Reding
<thierry.reding@xxxxxxxxx> wrote:
> On Wed, Apr 13, 2016 at 11:58:04AM +0530, Vinay Simha BN wrote:
>> Add support for the JDI lt070me05000 WUXGA DSI panel used in
>> Nexus 7 2013 devices.
>>
>> Programming sequence for the panel is was originally found in the
>> android-msm-flo-3.4-lollipop-release branch from:
>>     https://android.googlesource.com/kernel/msm.git
>>
>> And video mode setting is from dsi-panel-jdi-dualmipi1-video.dtsi
>> file in:
>>     git://codeaurora.org/kernel/msm-3.10.git  LNX.LA.3.6_rb1.27
>>
>> Other fixes folded in were provided
>> by Archit Taneja <archit.taneja@xxxxxxxxx>
>>
>> Signed-off-by: Vinay Simha BN <simhavcs@xxxxxxxxx>
>> [sumit.semwal: Ported to the drm/panel framework]
>> Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
>> [jstultz: Cherry-picked to mainline, folded down other fixes
>>  from Vinay and Archit]
>> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
>> ---
>>  .../bindings/display/panel/jdi,lt070me05000.txt    |  27 +
>>  .../devicetree/bindings/vendor-prefixes.txt        |   1 +
>>  drivers/gpu/drm/panel/Kconfig                      |  11 +
>>  drivers/gpu/drm/panel/Makefile                     |   1 +
>>  drivers/gpu/drm/panel/panel-jdi-lt070me05000.c     | 685 +++++++++++++++++++++
>>  5 files changed, 725 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/display/panel/jdi,lt070me05000.txt
>>  create mode 100644 drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
>
> What's the difference between this and the patch you sent earlier? I'm
> going to assume that the newer one is the correct patch, so I'll ignore
> the previous patch.
>
>> diff --git a/Documentation/devicetree/bindings/display/panel/jdi,lt070me05000.txt b/Documentation/devicetree/bindings/display/panel/jdi,lt070me05000.txt
>> new file mode 100644
>> index 0000000..35c5ac7
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/display/panel/jdi,lt070me05000.txt
>
> The binding documentation should be a separate patch.
>
>> @@ -0,0 +1,27 @@
>> +JDI model LT070ME05000 1920x1200 7" DSI Panel
>> +
>> +Basic data sheet is at:
>> +     http://panelone.net/en/7-0-inch/JDI_LT070ME05000_7.0_inch-datasheet
>> +
>> +This panel has video mode implemented currently in the driver.
>
> That's information irrelevant to the DT binding, since you're presumably
> talking about the Linux drm/panel driver, whereas the DT binding is
> supposed to specify the description of the panel hardware in OS-agnostic
> terms.
>
>> +Required properties:
>> +- compatible: should be "jdi,lt070me05000"
>> +
>> +Optional properties:
>> +- power-supply: phandle of the regulator that provides the supply voltage
>> +- reset-gpio: phandle of gpio for reset line
>> +- backlight: phandle of the backlight device attached to the panel
>> +
>> +Example:
>> +
>> +     dsi@54300000 {
>> +             panel: panel@0 {
>> +                     compatible = "jdi,lt070me05000";
>> +                     reg = <0>;
>> +
>> +                     power-supply = <...>;
>> +                     reset-gpio = <...>;
>> +                     backlight = <...>;
>> +             };
>> +     };
>> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> index a580f3e..ec42bb4 100644
>> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
>> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> @@ -130,6 +130,7 @@ invensense        InvenSense Inc.
>>  isee ISEE 2007 S.L.
>>  isil Intersil
>>  issi Integrated Silicon Solutions Inc.
>> +jdi  Japan Display Inc.
>>  jedec        JEDEC Solid State Technology Association
>>  karo Ka-Ro electronics GmbH
>>  keymile      Keymile GmbH
>
> This should be a separate patch as well.
>
>> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
>> index 1500ab9..f41690e 100644
>> --- a/drivers/gpu/drm/panel/Kconfig
>> +++ b/drivers/gpu/drm/panel/Kconfig
>> @@ -61,6 +61,17 @@ config DRM_PANEL_SHARP_LQ101R1SX01
>>         To compile this driver as a module, choose M here: the module
>>         will be called panel-sharp-lq101r1sx01.
>>
>> +config DRM_PANEL_JDI_LT070ME05000
>> +     tristate "JDI LT070ME05000 WUXGA DSI 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 JDI WUXGA DSI video/
>> +       command mode panel as found in Google Nexus 7 (2013) devices.
>> +       The panel has a 1200(RGB)Ã1920 (WUXGA) resolution and uses
>> +       24 bit RGB per pixel.
>> +
>>  config DRM_PANEL_SHARP_LS043T1LE01
>>       tristate "Sharp LS043T1LE01 qHD video mode panel"
>>       depends on OF
>
> Please keep these sorted alphabetically. I do realize that the list
> isn't sorted quite correctly at the moment, so you may as well leave
> this as-is and I'll fix up the order when applying and after fixing
> the current ordering.
>
>> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
>> index f277eed..e6c6fc8 100644
>> --- a/drivers/gpu/drm/panel/Makefile
>> +++ b/drivers/gpu/drm/panel/Makefile
>> @@ -5,3 +5,4 @@ obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
>>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E8AA0) += panel-samsung-s6e8aa0.o
>>  obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
>>  obj-$(CONFIG_DRM_PANEL_SHARP_LS043T1LE01) += panel-sharp-ls043t1le01.o
>> +obj-$(CONFIG_DRM_PANEL_JDI_LT070ME05000) += panel-jdi-lt070me05000.o
>
> Same here.
>
>> diff --git a/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c b/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
>> new file mode 100644
>> index 0000000..051aa1b
>> --- /dev/null
>> +++ b/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
>> @@ -0,0 +1,685 @@
>> +/*
>> + * Copyright (C) 2015 InforceComputing
>> + * Author: Vinay Simha BN <simhavcs@xxxxxxxxx>
>> + *
>> + * Copyright (C) 2015 Linaro Ltd
>> + * Author: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
>
> Should either of those copyright lines include 2016? We're a pretty good
> way into 2016, and I'd be surprised if this wasn't touched this year at
> all.
>
>> +/*
>> + * From internet archives, the panel for Nexus 7 2nd Gen, 2013 model is a
>> + * JDI model LT070ME05000, and its data sheet is at:
>> + *  http://panelone.net/en/7-0-inch/JDI_LT070ME05000_7.0_inch-datasheet
>> + */
>
> This comment is oddly placed here above the struct jdi_panel definition.
> Perhaps move that information into the header comment?
>
>> +struct jdi_panel {
>> +     struct drm_panel base;
>> +     struct mipi_dsi_device *dsi;
>> +
>> +     /* TODO: Add backilght support */
>
> "backlight". Also if this is still TODO, why even have parts of the code
> here? Just drop everything that's not used and move that to a follow-up
> patch that implements full support.
>
>> +     struct backlight_device *backlight;
>> +     struct regulator *supply;
>> +     struct gpio_desc *reset_gpio;
>> +     struct gpio_desc *enable_gpio;
>> +     struct gpio_desc *vcc_gpio;
>> +
>> +     struct regulator *backlit;
>> +     struct regulator *lvs7;
>> +     struct regulator *avdd;
>> +     struct regulator *iovdd;
>> +     struct gpio_desc *pwm_gpio;
>
> Most of these resources aren't specified in the device tree binding, so
> your driver doesn't properly implement the binding. You'll have to fix
> the driver or the binding.
>
>> +
>> +     bool prepared;
>> +     bool enabled;
>> +
>> +     const struct drm_display_mode *mode;
>> +};
>> +
>> +static inline struct jdi_panel *to_jdi_panel(struct drm_panel *panel)
>> +{
>> +     return container_of(panel, struct jdi_panel, base);
>> +}
>> +
>> +static char MCAP[2] = {0xB0, 0x00};
>> +static char interface_setting_cmd[6] = {0xB3, 0x04, 0x08, 0x00, 0x22, 0x00};
>> +static char interface_setting[6] = {0xB3, 0x26, 0x08, 0x00, 0x20, 0x00};
>
> Please make all of these (and the ones below) arrays of u8, since that's
> the type used in the prototype of the function that receives these as
> parameters. Also, please use consistent capitalization and a space after
> { and before }.
>
>> +static char interface_ID_setting[2] = {0xB4, 0x0C};
>> +static char DSI_control[3] = {0xB6, 0x3A, 0xD3};
>> +
>> +static char tear_scan_line[3] = {0x44, 0x03, 0x00};
>
> This is a standard DCS command, please turn this into a generic helper
> such as mipi_dsi_dcs_set_tear_scanline().
>
>> +/* for fps control, set fps to 60.32Hz */
>> +static char LTPS_timing_setting[2] = {0xC6, 0x78};
>> +static char sequencer_timing_control[2] = {0xD6, 0x01};
>> +
>> +/* set brightness */
>> +static char write_display_brightness[] = {0x51, 0xFF};
>
> Same here.
>
>> +/* enable LEDPWM pin output, turn on LEDPWM output, turn off pwm dimming */
>> +static char write_control_display[] = {0x53, 0x24};
>
> And here.
>
>> +/*
>> + * choose cabc mode, 0x00(-0%), 0x01(-15%), 0x02(-40%), 0x03(-54%),
>> + * disable SRE(sunlight readability enhancement)
>> + */
>> +static char write_cabc[] = {0x55, 0x00};
>
> And here.
>
>> +static int jdi_panel_init(struct jdi_panel *jdi)
>> +{
>> +     struct mipi_dsi_device *dsi = jdi->dsi;
>> +     int ret;
>> +
>> +     dsi->mode_flags |= MIPI_DSI_MODE_LPM;
>> +
>> +     if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO) {
>> +             ret = mipi_dsi_dcs_soft_reset(dsi);
>> +             if (ret < 0)
>> +                     return ret;
>> +
>> +             mdelay(10);
>
> Please don't use mdelay() because it will busy-loop for a very long time
> and waste precious CPU cycles. Instead, use usleep_range() for these
> cases (or msleep() for durations longer than ~10 ms). Same goes for the
> other occurrences below.
>
>> +
>> +             ret = mipi_dsi_dcs_set_pixel_format(dsi, 0x70);
>> +             if (ret < 0)
>> +                     return ret;
>
> There are symbolic constants for the pixel formats, use them to convey
> meaning.
>
>> +
>> +             ret = mipi_dsi_dcs_set_column_address(dsi, 0x0000, 0x04AF);
>> +             if (ret < 0)
>> +                     return ret;
>> +
>> +             ret = mipi_dsi_dcs_set_page_address(dsi, 0x0000, 0x077F);
>> +             if (ret < 0)
>> +                     return ret;
>
> These should be parameterized on the panel width and height, to make it
> clear where the values come from.
>
>> +
>> +             ret = mipi_dsi_dcs_set_tear_on(dsi,
>> +                                            MIPI_DSI_DCS_TEAR_MODE_VBLANK);
>> +             if (ret < 0)
>> +                     return ret;
>> +             mdelay(5);
>> +
>> +             ret = mipi_dsi_generic_write(dsi, tear_scan_line,
>> +                                          sizeof(tear_scan_line));
>> +             if (ret < 0)
>> +                     return ret;
>
> Like I mentioned earlier, this should be a generic helper to help make
> its intention clearer.
>
>> +
>> +             ret = mipi_dsi_dcs_write_buffer(dsi, write_display_brightness,
>> +                                             sizeof(write_display_brightness)
>> +                                             );
>> +             if (ret < 0)
>> +                     return ret;
>> +
>> +             ret = mipi_dsi_dcs_write_buffer(dsi, write_control_display,
>> +                                             sizeof(write_control_display));
>> +             if (ret < 0)
>> +                     return ret;
>> +
>> +             ret = mipi_dsi_dcs_write_buffer(dsi, write_cabc,
>> +                                             sizeof(write_cabc));
>> +             if (ret < 0)
>> +                     return ret;
>
> Same for these. I don't currently have access to the DCS 1.3
> specification, but I suspect that some of the parameters for these
> commands could be defined via symbolic names.
>
>> +
>> +             ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
>> +             if (ret < 0)
>> +                     return ret;
>> +             mdelay(120);
>> +
>> +             ret = mipi_dsi_generic_write(dsi, MCAP, sizeof(MCAP));
>> +             if (ret < 0)
>> +                     return ret;
>> +             mdelay(10);
>> +
>> +             ret = mipi_dsi_generic_write(dsi, interface_setting,
>> +                                          sizeof(interface_setting));
>> +             if (ret < 0)
>> +                     return ret;
>> +             mdelay(20);
>> +
>> +             backlight_control4[18] = 0x04;
>> +             backlight_control4[19] = 0x00;
>> +
>> +             ret = mipi_dsi_generic_write(dsi, backlight_control4,
>> +                                          sizeof(backlight_control4));
>> +             if (ret < 0)
>> +                     return ret;
>> +             mdelay(20);
>> +
>> +             MCAP[1] = 0x03;
>> +             ret = mipi_dsi_generic_write(dsi, MCAP, sizeof(MCAP));
>> +             if (ret < 0)
>> +                     return ret;
>
> That's odd. Doesn't this break idempotence of this function? You modify
> the global MCAP array by writing 0x03 to MCAP[1], so when this function
> is called a second time, MCAP[1] will be 0x03 already in the first call
> a few lines above, instead of the 0x00 that it was initially.
>
>> +     } else {
>> +             /*
>> +              * TODO : need to verify panel settings when
>> +              * dsi cmd mode supported for apq8064 - simhavcs
>> +              */
>> +             ret = mipi_dsi_dcs_soft_reset(dsi);
>> +             if (ret < 0)
>> +                     return ret;
>
> This whole else clause is dead code because the condition for the if
> clause is always true. Just drop it and add it back when you properly
> support both modes.
>
>> +static int jdi_panel_on(struct jdi_panel *jdi)
>> +{
>> +     struct mipi_dsi_device *dsi = jdi->dsi;
>> +     int ret;
>> +
>> +     dsi->mode_flags |= MIPI_DSI_MODE_LPM;
>> +
>> +     ret = mipi_dsi_dcs_set_display_on(dsi);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     return 0;
>> +}
>> +
>> +static int jdi_panel_off(struct jdi_panel *jdi)
>> +{
>> +     struct mipi_dsi_device *dsi = jdi->dsi;
>> +     int ret;
>> +
>> +     dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
>
> Should this not be cleared at the end of the function so that the below
> commands still get run in LP mode?
>
>> +
>> +     ret = mipi_dsi_dcs_set_display_off(dsi);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     ret = mipi_dsi_dcs_set_tear_off(dsi);
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     msleep(100);
>> +
>> +     return 0;
>> +}
>> +
>> +static int jdi_panel_disable(struct drm_panel *panel)
>> +{
>> +     struct jdi_panel *jdi = to_jdi_panel(panel);
>> +
>> +     if (!jdi->enabled)
>> +             return 0;
>> +
>> +     DRM_DEBUG("disable\n");
>
> This doesn't look very useful debug information. I think you should
> remove it. Same for other similar occurrences below.
>
>> +static const struct drm_panel_funcs jdi_panel_funcs = {
>> +             .disable = jdi_panel_disable,
>> +             .unprepare = jdi_panel_unprepare,
>> +             .prepare = jdi_panel_prepare,
>> +             .enable = jdi_panel_enable,
>> +             .get_modes = jdi_panel_get_modes,
>> +};
>> +
>> +static const struct of_device_id jdi_of_match[] = {
>> +             { .compatible = "jdi,lt070me05000", },
>> +             { }
>> +};
>> +MODULE_DEVICE_TABLE(of, jdi_of_match);
>
> A single tab is enough to indent the above.
>
>> +static int jdi_panel_add(struct jdi_panel *jdi)
>> +{
>> +     struct device *dev = &jdi->dsi->dev;
>> +     int ret;
>> +
>> +     jdi->mode = &default_mode;
>
> What do you keep this around for?
>
>> +
>> +     /* lvs5 */
>> +     jdi->supply = devm_regulator_get(dev, "power");
>> +     if (IS_ERR(jdi->supply))
>> +             return PTR_ERR(jdi->supply);
>> +
>> +     /* l17 */
>> +     jdi->backlit = devm_regulator_get(dev, "backlit");
>> +     if (IS_ERR(jdi->supply))
>> +             return PTR_ERR(jdi->supply);
>> +
>> +     jdi->lvs7 = devm_regulator_get(dev, "lvs7");
>> +     if (IS_ERR(jdi->lvs7))
>> +             return PTR_ERR(jdi->lvs7);
>> +
>> +     jdi->avdd = devm_regulator_get(dev, "avdd");
>> +     if (IS_ERR(jdi->avdd))
>> +             return PTR_ERR(jdi->avdd);
>> +
>> +     jdi->iovdd = devm_regulator_get(dev, "iovdd");
>> +     if (IS_ERR(jdi->iovdd))
>> +             return PTR_ERR(jdi->iovdd);
>> +
>> +     jdi->vcc_gpio = devm_gpiod_get(dev, "vcc", GPIOD_OUT_LOW);
>> +     if (IS_ERR(jdi->vcc_gpio)) {
>> +             dev_err(dev, "cannot get vcc-gpio %ld\n",
>> +                     PTR_ERR(jdi->vcc_gpio));
>> +             jdi->vcc_gpio = NULL;
>> +     } else {
>> +             gpiod_direction_output(jdi->vcc_gpio, 0);
>> +     }
>> +
>> +     jdi->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>> +     if (IS_ERR(jdi->reset_gpio)) {
>> +             dev_err(dev, "cannot get reset-gpios %ld\n",
>> +                     PTR_ERR(jdi->reset_gpio));
>> +             jdi->reset_gpio = NULL;
>> +     } else {
>> +             gpiod_direction_output(jdi->reset_gpio, 0);
>> +     }
>> +
>> +     jdi->enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
>> +     if (IS_ERR(jdi->enable_gpio)) {
>> +             dev_err(dev, "cannot get enable-gpio %ld\n",
>> +                     PTR_ERR(jdi->enable_gpio));
>> +             jdi->enable_gpio = NULL;
>> +     } else {
>> +             gpiod_direction_output(jdi->enable_gpio, 0);
>> +     }
>> +
>> +     jdi->pwm_gpio = devm_gpiod_get(dev, "pwm", GPIOD_OUT_LOW);
>> +     if (IS_ERR(jdi->pwm_gpio)) {
>> +             dev_err(dev, "cannot get pwm-gpio %ld\n",
>> +                     PTR_ERR(jdi->pwm_gpio));
>> +             jdi->pwm_gpio = NULL;
>> +     } else {
>> +             gpiod_direction_output(jdi->pwm_gpio, 0);
>> +     }
>
> As I said earlier, most of these aren't specified in the binding, fix
> either the binding or the code.
>
>> +     /* we don't have backlight right now, proceed further */
>> +#ifdef BACKLIGHT
>> +     np = of_parse_phandle(dev->of_node, "backlight", 0);
>> +     if (np) {
>> +             jdi->backlight = of_find_backlight_by_node(np);
>> +             of_node_put(np);
>> +
>> +             if (!jdi->backlight)
>> +                     return -EPROBE_DEFER;
>> +     }
>> +#endif
>
> Again, if you don't support it, don't submit it. We don't want dead code
> in the kernel.
>
>> +MODULE_AUTHOR("Sumit Semwal <sumit.semwal@xxxxxxxxxx>");
>> +MODULE_AUTHOR("Vinay Simha BN <simhavcs@xxxxxxxxx>");
>> +MODULE_DESCRIPTION("JDI WUXGA LT070ME05000 DSI video/command mode panel driver");
>
> Technically this doesn't support command mode yet, so you might want to
> remove that from the description to avoid confusion.
>
> Thierry



-- 
Regards,

Vinay Simha.B.N.