| Message ID | 20230918125853.2249187-4-contact@jookia.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add FS035VG158 panel | expand |
On Mon, Sep 18, 2023 at 01:19:03PM -0700, Jessica Zhang wrote: > Hi John, > > Just wondering, is there some context to this change? I.e., was this made to > fix a specific issue? > > This seems like a pretty significant increase in wait time so, if it's not a > fix, I'm not sure if this would be an improvement on the current behavior. > > Thanks, > > Jessica Zhang Hi Jessica, Thank you for the feedback. This patch here is required by the data sheet if the screen was already running and was reset. This is necessary if for example the bootloader set up and had the screen running. However I have not tested this, it's possible the specific panels have shorter tolerances for resets. This is purely precautionary at this stage based on what the data sheet says. That said I will be investigating this specific use case with this panel over the next few months. I am okay separating out this patch until I have proof it's needed for my particular display. I don't know anything about the ltk display. The second sleep patch can probably be omitted as I don't think the panel being prepared then unprepared in rapid succession is a realistic situation, but I figured I might as well propose it to see if it's the right thing to do. Thanks for your time and review, John.
On Mon, Sep 18, 2023 at 11:01:15PM +0200, Paul Cercueil wrote: > The datasheet does say a 5ms sleep time is necesary after a reset. I > assume the 120ms delay you quote is when a *software* reset is > performed in Sleep-out mode. The code here does a hard-reset. > > Cheers, > -Paul Hello Paul, Section 7.3 of the data sheet (AC characteristic) says that the reset can take up to 120ms to complete if the reset is applied during sleep out mode. John.
diff --git a/drivers/gpu/drm/panel/panel-newvision-nv3052c.c b/drivers/gpu/drm/panel/panel-newvision-nv3052c.c index 90dea21f9856..2526b123b1f5 100644 --- a/drivers/gpu/drm/panel/panel-newvision-nv3052c.c +++ b/drivers/gpu/drm/panel/panel-newvision-nv3052c.c @@ -258,7 +258,7 @@ static int nv3052c_prepare(struct drm_panel *panel) gpiod_set_value_cansleep(priv->reset_gpio, 1); usleep_range(10, 1000); gpiod_set_value_cansleep(priv->reset_gpio, 0); - usleep_range(5000, 20000); + msleep(150); for (i = 0; i < ARRAY_SIZE(nv3052c_panel_regs); i++) { err = mipi_dbi_command(dbi, nv3052c_panel_regs[i].cmd,
The current code waits after resets for 5 to 20 milliseconds. This is appropriate when resetting a sleeping panel, but an awake panel requires at least 120ms of waiting. Sleep for 150ms so the panel always completes it reset properly. Signed-off-by: John Watts <contact@jookia.org> --- drivers/gpu/drm/panel/panel-newvision-nv3052c.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)