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SubjectRe: [PATCH V7 2/2] drm/panel: Add Sitronix ST7701 panel driver
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Den 11.01.2019 22.19, skrev Sam Ravnborg:
> Hi Jagan.
>
> Gave this another more detailed read - triggered some additional comments.
> Depite the comments it looks good, and this is all more or
> less cosmetic improvements.
>
> Sam
>
>> +struct st7701_panel_desc {
>> + const struct drm_display_mode *mode;
>> + unsigned int lanes;
>> + unsigned long flags;
>> + enum mipi_dsi_pixel_format format;
>> + const char *const *supply_names;
>> + unsigned int num_supplies;
>> + unsigned int panel_sleep_delay;
>> +};
>> +
>> +struct st7701 {
>> + struct drm_panel panel;
>> + struct mipi_dsi_device *dsi;
>> + const struct st7701_panel_desc *desc;
>> +
>> + struct backlight_device *backlight;
>> + struct regulator_bulk_data *supplies;
>> + unsigned int num_supplies;
> I cannot see that num_supplies in this struct are used?
>
>
>> + struct gpio_desc *reset;
>> + unsigned int sleep_delay;
>> +};
>> +
>> +static inline struct st7701 *panel_to_st7701(struct drm_panel *panel)
>> +{
>> + return container_of(panel, struct st7701, panel);
>> +}
>> +
>> +static inline int st7701_dsi_write(struct st7701 *st7701, const void *seq,
>> + size_t len)
>> +{
>> + return mipi_dsi_dcs_write_buffer(st7701->dsi, seq, len);
>> +}
>> +
>
>
>> +static int st7701_prepare(struct drm_panel *panel)
>> +{
>> + struct st7701 *st7701 = panel_to_st7701(panel);
>> + int ret;
>> +
>> + gpiod_set_value(st7701->reset, 0);
>> + msleep(20);
>> +
>> + ret = regulator_bulk_enable(st7701->desc->num_supplies,
>> + st7701->supplies);
>> + if (ret < 0)
>> + return ret;
>> + msleep(20);
>> +
>> + gpiod_set_value(st7701->reset, 1);
>> + msleep(20);
>> +
>> + gpiod_set_value(st7701->reset, 0);
>> + msleep(30);
>> +
>> + gpiod_set_value(st7701->reset, 1);
>> + msleep(150);
>> +
>> + st7701_init_sequence(st7701);
>> +
>> + return 0;
>> +}
>> +
>
>> +static int st7701_unprepare(struct drm_panel *panel)
>> +{
>> + struct st7701 *st7701 = panel_to_st7701(panel);
>> +
>> + ST7701_DSI(st7701, MIPI_DCS_EXIT_SLEEP_MODE, 0x00);
>> +
>> + msleep(st7701->sleep_delay);
>> +
>> + gpiod_set_value(st7701->reset, 0);
>> +
>> + gpiod_set_value(st7701->reset, 1);
>> +
>> + gpiod_set_value(st7701->reset, 0);
> No timing constrains here? In prepare there are sleeps intermixed.
>
>> +
>> + regulator_bulk_disable(st7701->desc->num_supplies, st7701->supplies);
>> +
>> + return 0;
>> +}
>> +
>> +static int st7701_get_modes(struct drm_panel *panel)
>> +{
>> + struct st7701 *st7701 = panel_to_st7701(panel);
>> + const struct drm_display_mode *desc_mode = st7701->desc->mode;
>> + struct drm_display_mode *mode;
>> +
>> + mode = drm_mode_duplicate(panel->drm, desc_mode);
>> + if (!mode) {
>> + dev_err(&st7701->dsi->dev, "failed to add mode %ux%ux@%u\n",
>> + desc_mode->hdisplay, desc_mode->vdisplay,
>> + desc_mode->vrefresh);
> Use something like:
> DRM_DEV_ERROR(st7701->dev, "failed to add mode" DRM_MODE_FMT ",
> DRM_MODE_ARG(desc_mode));
>
>> + return -ENOMEM;
>> + }
>> +
>> + drm_mode_set_name(mode);
>> + drm_mode_probed_add(panel->connector, mode);
>> +
>> + panel->connector->display_info.width_mm = desc_mode->width_mm;
>> + panel->connector->display_info.height_mm = desc_mode->height_mm;
>> +
>> + return 1;
>> +}
>> +
>
>> +static const struct st7701_panel_desc ts8550b_desc = {
>> + .mode = &ts8550b_mode,
>> + .lanes = 2,
>> + .flags = MIPI_DSI_MODE_VIDEO,
>> + .format = MIPI_DSI_FMT_RGB888,
>> + .supply_names = ts8550b_supply_names,
>> + .num_supplies = ARRAY_SIZE(ts8550b_supply_names),
>> + .panel_sleep_delay = 80, /* panel need extra 80ms for sleep out cmd */
> In the only place this is used there is added 120 ms too.
> Looks inconsistent - do we have the same delay twice?
>
>
>> +
>> +static int st7701_dsi_probe(struct mipi_dsi_device *dsi)
>> +{
>> + const struct st7701_panel_desc *desc;
>> + struct device_node *np;
>> + struct st7701 *st7701;
>> + int ret, i;
>> +
>> + st7701 = devm_kzalloc(&dsi->dev, sizeof(*st7701), GFP_KERNEL);
>> + if (!st7701)
>> + return -ENOMEM;
>> +
>> + desc = of_device_get_match_data(&dsi->dev);
>> + dsi->mode_flags = desc->flags;
>> + dsi->format = desc->format;
>> + dsi->lanes = desc->lanes;
>> +
>> + st7701->supplies = devm_kcalloc(&dsi->dev, desc->num_supplies,
>> + sizeof(*st7701->supplies),
>> + GFP_KERNEL);
>> + if (!st7701->supplies)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < desc->num_supplies; i++)
>> + st7701->supplies[i].supply = desc->supply_names[i];
>> +
>> + ret = devm_regulator_bulk_get(&dsi->dev, desc->num_supplies,
>> + st7701->supplies);
>> + if (ret < 0)
>> + return ret;
>> +
>> + st7701->reset = devm_gpiod_get(&dsi->dev, "reset", GPIOD_OUT_LOW);
>> + if (IS_ERR(st7701->reset)) {
>> + dev_err(&dsi->dev, "Couldn't get our reset GPIO\n");
>> + return PTR_ERR(st7701->reset);
>> + }
>> +
>> + np = of_parse_phandle(dsi->dev.of_node, "backlight", 0);
>> + if (np) {
>> + st7701->backlight = of_find_backlight_by_node(np);
>> + of_node_put(np);
>> +
>> + if (!st7701->backlight)
>> + return -EPROBE_DEFER;
>> + }
> This is a simpler variant of the above:
> st7701->backlight = devm_of_find_backlight(dsi->dev);
> if (IS_ERR(st7701->backlight))
> return PTR_ERR(st7701->backlight);
>
> Suggested by Noralf in another thread for a similar driver.
>
>
>> +
>> + drm_panel_init(&st7701->panel);
>> +
>> + /* We need to wait 120ms after a sleep out command */
>> + st7701->sleep_delay = 120 + desc->panel_sleep_delay;
> This is the other place where we add 120 to the previous 80 - in total 200 ms.
>
>> + st7701->panel.funcs = &st7701_funcs;
>> + st7701->panel.dev = &dsi->dev;
>> +
>> + ret = drm_panel_add(&st7701->panel);
>> + if (ret < 0)
>> + return ret;
>> +
>> + mipi_dsi_set_drvdata(dsi, st7701);
>> + st7701->dsi = dsi;
>
>> + st7701->desc = desc;
> This assignment could come earlier, so we do not have it unassigned when calling
> other functions. As it is now it works so you can safely ignore this comment.
>
>> +
>> + return mipi_dsi_attach(dsi);
>> +}
>> +
>> +static int st7701_dsi_remove(struct mipi_dsi_device *dsi)
>> +{
>> + struct st7701 *st7701 = mipi_dsi_get_drvdata(dsi);
>> +
>> + mipi_dsi_detach(dsi);
>> + drm_panel_remove(&st7701->panel);
>> +
>> + if (st7701->backlight)
>> + put_device(&st7701->backlight->dev);
>
> Use:
> backlight_put(st7701->backlight);

This happens automatically on driver detach if devm_of_find_backlight()
is used

Noralf.

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