2022-07-07 08:41:37

by allen

Subject: [PATCH 1/3] drm/bridge: it6505: Modified power sequence

From: allen chen <[email protected]>

Change power sequence to meet it6505 data sheet requirement when boot on.

Signed-off-by: Pin-Yen Lin <[email protected]>
Signed-off-by: Allen Chen <[email protected]>

---
drivers/gpu/drm/bridge/ite-it6505.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index 2d119e3016b3..aa5e0aa1af85 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -3029,7 +3029,7 @@ static int it6505_init_pdata(struct it6505 *it6505)
return PTR_ERR(pdata->ovdd);
}

- pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+ pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
if (IS_ERR(pdata->gpiod_reset)) {
dev_err(dev, "gpiod_reset gpio not found");
return PTR_ERR(pdata->gpiod_reset);
--
2.25.1

2022-07-12 08:14:34

by Robert Foss

Subject: Re: [PATCH 1/3] drm/bridge: it6505: Modified power sequence

Hi Allen,

On Thu, 7 Jul 2022 at 10:06, allen <[email protected]> wrote:
>
> From: allen chen <[email protected]>
>
> Change power sequence to meet it6505 data sheet requirement when boot on.
>
> Signed-off-by: Pin-Yen Lin <[email protected]>
> Signed-off-by: Allen Chen <[email protected]>
>
> ---
> drivers/gpu/drm/bridge/ite-it6505.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 2d119e3016b3..aa5e0aa1af85 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -3029,7 +3029,7 @@ static int it6505_init_pdata(struct it6505 *it6505)
> return PTR_ERR(pdata->ovdd);
> }
>
> - pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> + pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);

Making this change is problematic since it requires a corresponding
change in all of the device trees that use this device. It's against
policy to change this interface after it has been introduced.

Unless anyone thinks otherwise, I would like to see this patch dropped.

> if (IS_ERR(pdata->gpiod_reset)) {
> dev_err(dev, "gpiod_reset gpio not found");
> return PTR_ERR(pdata->gpiod_reset);
> --
> 2.25.1
>

2022-07-12 09:34:35

by Pin-yen Lin

Subject: Re: [PATCH 1/3] drm/bridge: it6505: Modified power sequence

Hi Robert,

On Tue, Jul 12, 2022 at 4:07 PM Robert Foss <[email protected]> wrote:
>
> Hi Allen,
>
> On Thu, 7 Jul 2022 at 10:06, allen <[email protected]> wrote:
> >
> > From: allen chen <[email protected]>
> >
> > Change power sequence to meet it6505 data sheet requirement when boot on.
> >
> > Signed-off-by: Pin-Yen Lin <[email protected]>
> > Signed-off-by: Allen Chen <[email protected]>
> >
> > ---
> > drivers/gpu/drm/bridge/ite-it6505.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> > index 2d119e3016b3..aa5e0aa1af85 100644
> > --- a/drivers/gpu/drm/bridge/ite-it6505.c
> > +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> > @@ -3029,7 +3029,7 @@ static int it6505_init_pdata(struct it6505 *it6505)
> > return PTR_ERR(pdata->ovdd);
> > }
> >
> > - pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> > + pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>
> Making this change is problematic since it requires a corresponding
> change in all of the device trees that use this device. It's against
> policy to change this interface after it has been introduced.
>
> Unless anyone thinks otherwise, I would like to see this patch dropped.

I don't really understand why this would require corresponding change
in device trees.

Currently there's no real it6505 user on upstream. Also, the GPIO
value will be changed
in it6505_poweron, so this change only affects the power on sequence of it6505.

>
> > if (IS_ERR(pdata->gpiod_reset)) {
> > dev_err(dev, "gpiod_reset gpio not found");
> > return PTR_ERR(pdata->gpiod_reset);
> > --
> > 2.25.1
> >

2022-07-12 10:08:44

by Chen-Yu Tsai

Subject: Re: [PATCH 1/3] drm/bridge: it6505: Modified power sequence

On Tue, Jul 12, 2022 at 4:08 PM Robert Foss <[email protected]> wrote:
>
> Hi Allen,
>
> On Thu, 7 Jul 2022 at 10:06, allen <[email protected]> wrote:
> >
> > From: allen chen <[email protected]>
> >
> > Change power sequence to meet it6505 data sheet requirement when boot on.
> >
> > Signed-off-by: Pin-Yen Lin <[email protected]>
> > Signed-off-by: Allen Chen <[email protected]>
> >
> > ---
> > drivers/gpu/drm/bridge/ite-it6505.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> > index 2d119e3016b3..aa5e0aa1af85 100644
> > --- a/drivers/gpu/drm/bridge/ite-it6505.c
> > +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> > @@ -3029,7 +3029,7 @@ static int it6505_init_pdata(struct it6505 *it6505)
> > return PTR_ERR(pdata->ovdd);
> > }
> >
> > - pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> > + pdata->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>
> Making this change is problematic since it requires a corresponding
> change in all of the device trees that use this device. It's against
> policy to change this interface after it has been introduced.
>
> Unless anyone thinks otherwise, I would like to see this patch dropped.

I think you're confusing GPIO_ACTIVE_{LOW,HIGH} flags in the device tree
vs GPIOD_OUT_{LOW,HIGH}, which just sets the "default" state the GPIO
should be in when it is requested.

This change doesn't impact the device tree.


Regards
ChenYu

> > if (IS_ERR(pdata->gpiod_reset)) {
> > dev_err(dev, "gpiod_reset gpio not found");
> > return PTR_ERR(pdata->gpiod_reset);
> > --
> > 2.25.1
> >