At present, we have found that there may be a problem of blurred screen during fast sleep/resume. The direct cause of the blurred screen is that the IC does not receive 0x28/0x10. Because of the particularity of the IC, before the panel enters sleep hid must stop scanning, i2c_hid_core_suspend before ili9882t_disable. This doesn't look very spec-compliant. So in order to solve this problem, the IC can handle it through the exception mechanism when it cannot receive 0X28/0X10 command. Handling exceptions requires a reset 50ms delay. Refer to vendor detailed analysis [1].
Ilitek vendor also suggested switching the page before entering sleep to avoid panel IC not receiving 0x28/0x10 command. Note: 0x28 is display off, 0x10 is sleep in. [1]: https://github.com/ILITEK-LoganLin/Document/tree/main/ILITEK_Power_Sequence Signed-off-by: Cong Yang <yangco...@huaqin.corp-partner.google.com> --- drivers/gpu/drm/panel/panel-ilitek-ili9882t.c | 21 ++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c b/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c index bbfcffe65623..0a1dd987b204 100644 --- a/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c +++ b/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c @@ -423,6 +423,23 @@ static inline struct ili9882t *to_ili9882t(struct drm_panel *panel) return container_of(panel, struct ili9882t, base); } +static int ili9882t_switch_page(struct mipi_dsi_device *dsi, u8 page) +{ + u8 switch_cmd[] = {0x98, 0x82, 0x00}; + int ret; + + switch_cmd[2] = page; + + ret = mipi_dsi_dcs_write(dsi, ILI9882T_DCS_SWITCH_PAGE, switch_cmd, 3); + if (ret) { + dev_err(&dsi->dev, + "error switching panel controller page (%d)\n", ret); + return ret; + } + + return 0; +} + static int ili9882t_enter_sleep_mode(struct ili9882t *ili) { struct mipi_dsi_device *dsi = ili->dsi; @@ -444,8 +461,10 @@ static int ili9882t_enter_sleep_mode(struct ili9882t *ili) static int ili9882t_disable(struct drm_panel *panel) { struct ili9882t *ili = to_ili9882t(panel); + struct mipi_dsi_device *dsi = ili->dsi; int ret; + ili9882t_switch_page(dsi, 0x00); ret = ili9882t_enter_sleep_mode(ili); if (ret < 0) { dev_err(panel->dev, "failed to set panel off: %d\n", ret); @@ -507,7 +526,7 @@ static int ili9882t_prepare(struct drm_panel *panel) gpiod_set_value(ili->enable_gpio, 1); usleep_range(1000, 2000); gpiod_set_value(ili->enable_gpio, 0); - usleep_range(1000, 2000); + usleep_range(40000, 50000); gpiod_set_value(ili->enable_gpio, 1); usleep_range(6000, 10000); -- 2.25.1
