Hi,
On Fri, Oct 6, 2023 at 11:07 PM Cong Yang
<[email protected]> 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, i2c_hid_core_suspend before ili9882t_disable.
> This doesn't look very spec-compliant.
Presumably you could be more spec compliant if we used
"panel_follower" in this case? Would that be a better solution?
> 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 <[email protected]>
> ---
> 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};
Can't you just replace the last 0x00 above with "page" and get rid of
the manual assignment below?
> + int ret;
> +
> + switch_cmd[2] = page;
> +
> + ret = mipi_dsi_dcs_write(dsi, ILI9882T_DCS_SWITCH_PAGE, switch_cmd, 3);
Instead of hardcoding 3, should use ARRAY_SIZE().
> + if (ret) {
> + dev_err(&dsi->dev,
> + "error switching panel controller page (%d)\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
optional: It feels like it would be nice to somehow use the
"_INIT_SWITCH_PAGE_CMD" macro I suggested in patch #1 instead of
having to hardcode 0x98, 0x82 again. In patch #1 I already suggested
breaking out the function to send a sequence of commands. If you had
that function take a pointer instead of hardcoding it to look at
->init_cmds then you could probably use the same function that you do
at init time?
> 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);
nit: use 40000, 41000 instead of 40000, 50000. Linux almost always
uses the longer delay, so that'll save ~9 ms. The only reason for the
range is to optimize kernel wakeups which is really not a concern
here.