diff mbox series

[v7,05/10] drm: bridge: samsung-dsim: Add atomic_check

Message ID 20221005151309.7278-6-jagan@amarulasolutions.com
State New
Headers show
Series drm: bridge: Add Samsung MIPI DSIM bridge | expand

Commit Message

Jagan Teki Oct. 5, 2022, 3:13 p.m. UTC 
Look like an explicit fixing up of mode_flags is required for DSIM IP
present in i.MX8M Mini/Nano SoCs.

At least the LCDIF + DSIM needs active low sync polarities in order
to correlate the correct sync flags of the surrounding components in
the chain to make sure the whole pipeline can work properly.

On the other hand the i.MX 8M Mini Applications Processor Reference Manual,
Rev. 3, 11/2020 says.
"13.6.3.5.2 RGB interface
 Vsync, Hsync, and VDEN are active high signals."

No clear evidence about whether it can be documentation issues or
something, so added a comment FIXME for this and updated the active low
sync polarities using SAMSUNG_DSIM_TYPE_IMX8MM hw_type.

v7:
* fix the hw_type checking logic

v6:
* none

v5:
* rebase based new bridge changes [mszyprow]
* remove DSIM_QUIRK_FIXUP_SYNC_POL
* add hw_type check for sync polarities change.

v4:
* none

v3:
* add DSIM_QUIRK_FIXUP_SYNC_POL to handle mode_flasg fixup

v2:
* none

v1:
* fix mode flags in atomic_check instead of mode_fixup

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

Comments

Marek Vasut Oct. 15, 2022, 9:23 p.m. UTC | #1 
On 10/5/22 17:13, Jagan Teki wrote:
> Look like an explicit fixing up of mode_flags is required for DSIM IP
> present in i.MX8M Mini/Nano SoCs.
> 
> At least the LCDIF + DSIM needs active low sync polarities in order
> to correlate the correct sync flags of the surrounding components in
> the chain to make sure the whole pipeline can work properly.
> 
> On the other hand the i.MX 8M Mini Applications Processor Reference Manual,
> Rev. 3, 11/2020 says.
> "13.6.3.5.2 RGB interface
>   Vsync, Hsync, and VDEN are active high signals."
> 
> No clear evidence about whether it can be documentation issues or
> something, so added a comment FIXME for this and updated the active low
> sync polarities using SAMSUNG_DSIM_TYPE_IMX8MM hw_type.

[...]

> +static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
> +				     struct drm_bridge_state *bridge_state,
> +				     struct drm_crtc_state *crtc_state,
> +				     struct drm_connector_state *conn_state)
> +{
> +	struct samsung_dsim *dsi = bridge_to_dsi(bridge);
> +	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
> +
> +	if (dsi->plat_data->hw_type == SAMSUNG_DSIM_TYPE_IMX8MM) {
> +		/**
> +		 * FIXME:
> +		 * At least LCDIF + DSIM needs active low sync,
> +		 * but i.MX 8M Mini Applications Processor Reference Manual,
> +		 * Rev. 3, 11/2020 says
> +		 *
> +		 * 13.6.3.5.2 RGB interface
> +		 * Vsync, Hsync, and VDEN are active high signals.
> +		 */
> +		adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> +		adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> +	}

It would be good to explain what exactly is going on here in the 
comment, the comment says "Vsync, Hsync, and VDEN are active high 
signals." and the code below does exact opposite and sets NxSYNC flags.

Yes, the MX8MM/MN does need HS/VS/DE active LOW, it is a quirk of that 
MXSFB-DSIM glue logic. The MX8MP needs the exact opposite on all three, 
active HIGH.

It would also be good to mention both MX8MM and MX8MN are affected, not 
only MX8MM.
Jagan Teki Oct. 17, 2022, 3:54 a.m. UTC | #2 
On Sun, Oct 16, 2022 at 2:53 AM Marek Vasut <marex@denx.de> wrote:
>
> On 10/5/22 17:13, Jagan Teki wrote:
> > Look like an explicit fixing up of mode_flags is required for DSIM IP
> > present in i.MX8M Mini/Nano SoCs.
> >
> > At least the LCDIF + DSIM needs active low sync polarities in order
> > to correlate the correct sync flags of the surrounding components in
> > the chain to make sure the whole pipeline can work properly.
> >
> > On the other hand the i.MX 8M Mini Applications Processor Reference Manual,
> > Rev. 3, 11/2020 says.
> > "13.6.3.5.2 RGB interface
> >   Vsync, Hsync, and VDEN are active high signals."
> >
> > No clear evidence about whether it can be documentation issues or
> > something, so added a comment FIXME for this and updated the active low
> > sync polarities using SAMSUNG_DSIM_TYPE_IMX8MM hw_type.
>
> [...]
>
> > +static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
> > +                                  struct drm_bridge_state *bridge_state,
> > +                                  struct drm_crtc_state *crtc_state,
> > +                                  struct drm_connector_state *conn_state)
> > +{
> > +     struct samsung_dsim *dsi = bridge_to_dsi(bridge);
> > +     struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
> > +
> > +     if (dsi->plat_data->hw_type == SAMSUNG_DSIM_TYPE_IMX8MM) {
> > +             /**
> > +              * FIXME:
> > +              * At least LCDIF + DSIM needs active low sync,
> > +              * but i.MX 8M Mini Applications Processor Reference Manual,
> > +              * Rev. 3, 11/2020 says
> > +              *
> > +              * 13.6.3.5.2 RGB interface
> > +              * Vsync, Hsync, and VDEN are active high signals.
> > +              */
> > +             adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> > +             adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> > +     }
>
> It would be good to explain what exactly is going on here in the
> comment, the comment says "Vsync, Hsync, and VDEN are active high
> signals." and the code below does exact opposite and sets NxSYNC flags.
>
> Yes, the MX8MM/MN does need HS/VS/DE active LOW, it is a quirk of that
> MXSFB-DSIM glue logic. The MX8MP needs the exact opposite on all three,
> active HIGH.

This is what exactly is mentioned in the comments.

2nd line mentioned the active low of signals.
> > +              * At least LCDIF + DSIM needs active low sync,

from 3rd line onwards it mentioned what reference manual is referring

Not quite understand what is misleading here.

>
> It would also be good to mention both MX8MM and MX8MN are affected, not
> only MX8MM.

I think I can do this once I refer to the MX8MN manual.

Jagan.
Marek Vasut Oct. 17, 2022, 7:23 a.m. UTC | #3 
On 10/17/22 05:54, Jagan Teki wrote:
> On Sun, Oct 16, 2022 at 2:53 AM Marek Vasut <marex@denx.de> wrote:
>>
>> On 10/5/22 17:13, Jagan Teki wrote:
>>> Look like an explicit fixing up of mode_flags is required for DSIM IP
>>> present in i.MX8M Mini/Nano SoCs.
>>>
>>> At least the LCDIF + DSIM needs active low sync polarities in order
>>> to correlate the correct sync flags of the surrounding components in
>>> the chain to make sure the whole pipeline can work properly.
>>>
>>> On the other hand the i.MX 8M Mini Applications Processor Reference Manual,
>>> Rev. 3, 11/2020 says.
>>> "13.6.3.5.2 RGB interface
>>>    Vsync, Hsync, and VDEN are active high signals."
>>>
>>> No clear evidence about whether it can be documentation issues or
>>> something, so added a comment FIXME for this and updated the active low
>>> sync polarities using SAMSUNG_DSIM_TYPE_IMX8MM hw_type.
>>
>> [...]
>>
>>> +static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
>>> +                                  struct drm_bridge_state *bridge_state,
>>> +                                  struct drm_crtc_state *crtc_state,
>>> +                                  struct drm_connector_state *conn_state)
>>> +{
>>> +     struct samsung_dsim *dsi = bridge_to_dsi(bridge);
>>> +     struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
>>> +
>>> +     if (dsi->plat_data->hw_type == SAMSUNG_DSIM_TYPE_IMX8MM) {
>>> +             /**
>>> +              * FIXME:
>>> +              * At least LCDIF + DSIM needs active low sync,
>>> +              * but i.MX 8M Mini Applications Processor Reference Manual,
>>> +              * Rev. 3, 11/2020 says
>>> +              *
>>> +              * 13.6.3.5.2 RGB interface
>>> +              * Vsync, Hsync, and VDEN are active high signals.
>>> +              */
>>> +             adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
>>> +             adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
>>> +     }
>>
>> It would be good to explain what exactly is going on here in the
>> comment, the comment says "Vsync, Hsync, and VDEN are active high
>> signals." and the code below does exact opposite and sets NxSYNC flags.
>>
>> Yes, the MX8MM/MN does need HS/VS/DE active LOW, it is a quirk of that
>> MXSFB-DSIM glue logic. The MX8MP needs the exact opposite on all three,
>> active HIGH.
> 
> This is what exactly is mentioned in the comments.
> 
> 2nd line mentioned the active low of signals.
>>> +              * At least LCDIF + DSIM needs active low sync,
> 
> from 3rd line onwards it mentioned what reference manual is referring
> 
> Not quite understand what is misleading here.

This part:
"
+  * Vsync, Hsync, and VDEN are active high signals.
+  */
+  adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
"

Comment claims the signals are active high by quoting datasheet, and 
then sets the exact opposite on next line of code.

Have a look at this patch, I updated the comment there for MX8MP too:
[PATCH] drm: bridge: samsung-dsim: Add i.MX8M Plus support
Jagan Teki Oct. 17, 2022, 7:51 a.m. UTC | #4 
On Mon, Oct 17, 2022 at 12:53 PM Marek Vasut <marex@denx.de> wrote:
>
> On 10/17/22 05:54, Jagan Teki wrote:
> > On Sun, Oct 16, 2022 at 2:53 AM Marek Vasut <marex@denx.de> wrote:
> >>
> >> On 10/5/22 17:13, Jagan Teki wrote:
> >>> Look like an explicit fixing up of mode_flags is required for DSIM IP
> >>> present in i.MX8M Mini/Nano SoCs.
> >>>
> >>> At least the LCDIF + DSIM needs active low sync polarities in order
> >>> to correlate the correct sync flags of the surrounding components in
> >>> the chain to make sure the whole pipeline can work properly.
> >>>
> >>> On the other hand the i.MX 8M Mini Applications Processor Reference Manual,
> >>> Rev. 3, 11/2020 says.
> >>> "13.6.3.5.2 RGB interface
> >>>    Vsync, Hsync, and VDEN are active high signals."
> >>>
> >>> No clear evidence about whether it can be documentation issues or
> >>> something, so added a comment FIXME for this and updated the active low
> >>> sync polarities using SAMSUNG_DSIM_TYPE_IMX8MM hw_type.
> >>
> >> [...]
> >>
> >>> +static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
> >>> +                                  struct drm_bridge_state *bridge_state,
> >>> +                                  struct drm_crtc_state *crtc_state,
> >>> +                                  struct drm_connector_state *conn_state)
> >>> +{
> >>> +     struct samsung_dsim *dsi = bridge_to_dsi(bridge);
> >>> +     struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
> >>> +
> >>> +     if (dsi->plat_data->hw_type == SAMSUNG_DSIM_TYPE_IMX8MM) {
> >>> +             /**
> >>> +              * FIXME:
> >>> +              * At least LCDIF + DSIM needs active low sync,
> >>> +              * but i.MX 8M Mini Applications Processor Reference Manual,
> >>> +              * Rev. 3, 11/2020 says
> >>> +              *
> >>> +              * 13.6.3.5.2 RGB interface
> >>> +              * Vsync, Hsync, and VDEN are active high signals.
> >>> +              */
> >>> +             adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> >>> +             adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> >>> +     }
> >>
> >> It would be good to explain what exactly is going on here in the
> >> comment, the comment says "Vsync, Hsync, and VDEN are active high
> >> signals." and the code below does exact opposite and sets NxSYNC flags.
> >>
> >> Yes, the MX8MM/MN does need HS/VS/DE active LOW, it is a quirk of that
> >> MXSFB-DSIM glue logic. The MX8MP needs the exact opposite on all three,
> >> active HIGH.
> >
> > This is what exactly is mentioned in the comments.
> >
> > 2nd line mentioned the active low of signals.
> >>> +              * At least LCDIF + DSIM needs active low sync,
> >
> > from 3rd line onwards it mentioned what reference manual is referring
> >
> > Not quite understand what is misleading here.
>
> This part:
> "
> +  * Vsync, Hsync, and VDEN are active high signals.
> +  */
> +  adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> "
>
> Comment claims the signals are active high by quoting datasheet, and
> then sets the exact opposite on next line of code.

The comment stated what is done first and then gave the datasheet
reference. look this sequence seems confusing, I will recheck and
update the best possible comment.

>
> Have a look at this patch, I updated the comment there for MX8MP too:
> [PATCH] drm: bridge: samsung-dsim: Add i.MX8M Plus support

I will check.

Thanks,
Jagan.
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 563781bb27c4..b46346232c52 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1315,6 +1315,31 @@  static void samsung_dsim_atomic_post_disable(struct drm_bridge *bridge,
 	pm_runtime_put_sync(dsi->dev);
 }
 
+static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
+				     struct drm_bridge_state *bridge_state,
+				     struct drm_crtc_state *crtc_state,
+				     struct drm_connector_state *conn_state)
+{
+	struct samsung_dsim *dsi = bridge_to_dsi(bridge);
+	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
+
+	if (dsi->plat_data->hw_type == SAMSUNG_DSIM_TYPE_IMX8MM) {
+		/**
+		 * FIXME:
+		 * At least LCDIF + DSIM needs active low sync,
+		 * but i.MX 8M Mini Applications Processor Reference Manual,
+		 * Rev. 3, 11/2020 says
+		 *
+		 * 13.6.3.5.2 RGB interface
+		 * Vsync, Hsync, and VDEN are active high signals.
+		 */
+		adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
+		adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
+	}
+
+	return 0;
+}
+
 static void samsung_dsim_mode_set(struct drm_bridge *bridge,
 				  const struct drm_display_mode *mode,
 				  const struct drm_display_mode *adjusted_mode)
@@ -1353,6 +1378,7 @@  static const struct drm_bridge_funcs samsung_dsim_bridge_funcs = {
 	.atomic_duplicate_state		= drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state		= drm_atomic_helper_bridge_destroy_state,
 	.atomic_reset			= drm_atomic_helper_bridge_reset,
+	.atomic_check			= samsung_dsim_atomic_check,
 	.atomic_pre_enable		= samsung_dsim_atomic_pre_enable,
 	.atomic_enable			= samsung_dsim_atomic_enable,
 	.atomic_disable			= samsung_dsim_atomic_disable,