[v4,2/3] drm/panel: ili9882t: Avoid blurred screen from fast sleep

Commit Message

cong yang Oct. 13, 2023, 9:18 a.m. UTC

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, as i2c_hid_core_suspend before ili9882t_disable.
If move the ili9882t_enter_sleep_mode function to ili9882t_unprepare,
touch reset will pull low before panel entersleep, which does not meet
the timing requirements.. 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 <[e-mail]>
---
 drivers/gpu/drm/panel/panel-ilitek-ili9882t.c | 22 ++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

Comments

Doug Anderson Oct. 13, 2023, 9:43 p.m. UTC | #1

Hi,

On Fri, Oct 13, 2023 at 2:19 AM Cong Yang
<[e-mail]> wrote:
>
> 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, as i2c_hid_core_suspend before ili9882t_disable.
> If move the ili9882t_enter_sleep_mode function to ili9882t_unprepare,
> touch reset will pull low before panel entersleep, which does not meet
> the timing requirements.. 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 <[e-mail]>
> ---
>  drivers/gpu/drm/panel/panel-ilitek-ili9882t.c | 22 ++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)

As talked about in response to the previous version [1], we can work
to see if we can improve the sequencing. However, for now this seems
fine.

Reviewed-by: Douglas Anderson <[e-mail]>

[1] https://lore.kernel.org/r/CAD=FV=[e-mail]

Doug Anderson Oct. 19, 2023, 9:50 p.m. UTC | #2

Hi,

On Fri, Oct 13, 2023 at 2:43 PM Doug Anderson <[e-mail]> wrote:
>
> Hi,
>
> On Fri, Oct 13, 2023 at 2:19 AM Cong Yang
> <[e-mail]> wrote:
> >
> > 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, as i2c_hid_core_suspend before ili9882t_disable.
> > If move the ili9882t_enter_sleep_mode function to ili9882t_unprepare,
> > touch reset will pull low before panel entersleep, which does not meet
> > the timing requirements.. 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 <[e-mail]>
> > ---
> >  drivers/gpu/drm/panel/panel-ilitek-ili9882t.c | 22 ++++++++++++++++++-
> >  1 file changed, 21 insertions(+), 1 deletion(-)
>
> As talked about in response to the previous version [1], we can work
> to see if we can improve the sequencing. However, for now this seems
> fine.
>
> Reviewed-by: Douglas Anderson <[e-mail]>
>
> [1] https://lore.kernel.org/r/CAD=FV=[e-mail]

Pushed to drm-misc-next:

5820a1932ce8 drm/panel: ili9882t: Avoid blurred screen from fast sleep

Patch

diff --git a/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c b/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c
index 93a40c2f1483..267a5307041c 100644
--- a/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c
+++ b/drivers/gpu/drm/panel/panel-ilitek-ili9882t.c
@@ -463,6 +463,24 @@  static int ili9882t_init_dcs_cmd(struct ili9882t *ili)
 	return 0;
 }
 
+static int ili9882t_switch_page(struct mipi_dsi_device *dsi, u8 page)
+{
+	int ret;
+	const struct panel_init_cmd cmd = _INIT_SWITCH_PAGE_CMD(page);
+
+	ret = mipi_dsi_dcs_write(dsi, cmd.data[0],
+				 cmd.len <= 1 ? NULL :
+				 &cmd.data[1],
+				 cmd.len - 1);
+	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;
@@ -484,8 +502,10 @@  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);
@@ -546,7 +566,7 @@  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);
+	msleep(50);
 	gpiod_set_value(ili->enable_gpio, 1);
 	usleep_range(6000, 10000);