Re: [Intel-gfx] [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
Hi,
On Tue, Oct 18, 2022 at 11:28:35PM +0200, Mateusz Kwiatkowski wrote:
> W dniu 18.10.2022 o 12:00, Maxime Ripard pisze:
> > On Mon, Oct 17, 2022 at 12:31:31PM +0200, Noralf Trønnes wrote:
> >> Den 16.10.2022 20.52, skrev Mateusz Kwiatkowski:
> static int vc4_vec_connector_get_modes(struct drm_connector *connector)
> {
> -struct drm_connector_state *state = connector->state;
> struct drm_display_mode *mode;
>
> -mode = drm_mode_duplicate(connector->dev,
> -
> vc4_vec_tv_modes[state->tv.legacy_mode].mode);
> +mode = drm_mode_analog_ntsc_480i(connector->dev);
> if (!mode) {
> DRM_ERROR("Failed to create a new display mode\n");
> return -ENOMEM;
> }
>
> +mode->type |= DRM_MODE_TYPE_PREFERRED;
> drm_mode_probed_add(connector, mode);
>
> -return 1;
> +mode = drm_mode_analog_pal_576i(connector->dev);
> +if (!mode) {
> +DRM_ERROR("Failed to create a new display mode\n");
> +return -ENOMEM;
> +}
> +
> +drm_mode_probed_add(connector, mode);
> +
> +return 2;
> +}
> >>>
> >>> Referencing those previous discussions:
> >>> -
> >>> https://lore.kernel.org/dri-devel/0255f7c6-0484-6456-350d-cf24f3fee...@tronnes.org/
> >>> -
> >>> https://lore.kernel.org/dri-devel/c8f8015a-75da-afa8-ca7f-b2b134cac...@gmail.com/
> >>>
> >>> Unconditionally setting the 480i mode as DRM_MODE_TYPE_PREFERRED causes
> >>> Xorg
> >>> (at least on current Raspberry Pi OS) to display garbage when
> >>> video=Composite1:PAL is specified on the command line, so I'm afraid this
> >>> won't
> >>> do.
> >>>
> >>> As I see it, there are three viable solutions for this issue:
> >>>
> >>> a) Somehow query the video= command line option from this function, and
> >>> set
> >>>DRM_MODE_TYPE_PREFERRED appropriately. This would break the abstraction
> >>>provided by global DRM code, but should work fine.
> >>>
> >>> b) Modify drm_helper_probe_add_cmdline_mode() so that it sets
> >>>DRM_MODE_TYPE_PREFERRED in addition to DRM_MODE_TYPE_USERDEF. This
> >>> seems
> >>>pretty robust, but affects the entire DRM subsystem, which may break
> >>>userspace in different ways.
> >>>
> >>>- Maybe this could be mitigated by adding some additional conditions,
> >>> e.g.
> >>> setting the PREFERRED flag only if no modes are already flagged as
> >>> such
> >>> and/or only if the cmdline mode is a named one (~= analog TV mode)
> >>>
> >>> c) Forcing userspace (Xorg / Raspberry Pi OS) to get fixed and honor the
> >>> USERDEF
> >>>flag.
> >>>
> >>> Either way, hardcoding 480i as PREFERRED does not seem right.
> >>>
> >>
> >> My solution for this is to look at tv.mode to know which mode to mark as
> >> preferred. Maxime didn't like this since it changes things behind
> >> userspace's back. I don't see how that can cause any problems for
> >> userspace.
> >>
> >> If userspace uses atomic and sets tv_mode, it has to know which mode to
> >> use before hand, so it doesn't look at the preferreded flag.
> >>
> >> If it uses legacy and sets tv_mode, it can end up with a stale preferred
> >> flag, but no worse than not having the flag or that ntsc is always
> >> preferred.
> >>
> >> If it doesn't change tv_mode, there's no problem, the preferred flag
> >> doesn't change.
> >
> > I don't like it because I just see no way to make this reliable. When we
> > set tv_mode, we're not only going to change the preferred flag, but also
> > the order of the modes to make the preferred mode first.
> >
> > Since we just changed the mode lists, we also want to send a hotplug
> > event to userspace so that it gets notified of it. It will pick up the
> > new preferred mode, great.
> >
> > But what if it doesn't? There's no requirement for userspace to handle
> > hotplug events, and Kodi won't for example. So we just changed the TV
> > mode but not the actual mode, and that's it. It's just as broken for
> > Kodi as it is for X11 right now.
> >
> > If we can't get a bullet-proof solution, then I'm not convinced it's
> > worth addressing. Especially since it's already the current state, and
> > it doesn't seem to bother a lot of people.
>
> I wouldn't rely on the "doesn't seem to bother a lot of people" bit too much.
> Here's why:
>
> - Analog TV output is a relatively obscure feature in this day and age in the
> first place.
>
> - Out of the people interested in using it with VC4/VEC, many are actually
> using
> the downstream kernel from https://github.com/raspberrypi/linux instead of
> the
> upstream kernel, and/or firmware mode-switching instead of proper KMS.
>
> - The downstream kernel only reports modes that match the TV mode set at
> boot
> either via vc4.tv_norm=, or implie
Re: [Intel-gfx] [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
Hi Maxime,
W dniu 18.10.2022 o 12:00, Maxime Ripard pisze:
> On Mon, Oct 17, 2022 at 12:31:31PM +0200, Noralf Trønnes wrote:
>> Den 16.10.2022 20.52, skrev Mateusz Kwiatkowski:
static int vc4_vec_connector_get_modes(struct drm_connector *connector)
{
- struct drm_connector_state *state = connector->state;
struct drm_display_mode *mode;
- mode = drm_mode_duplicate(connector->dev,
-vc4_vec_tv_modes[state->tv.legacy_mode].mode);
+ mode = drm_mode_analog_ntsc_480i(connector->dev);
if (!mode) {
DRM_ERROR("Failed to create a new display mode\n");
return -ENOMEM;
}
+ mode->type |= DRM_MODE_TYPE_PREFERRED;
drm_mode_probed_add(connector, mode);
- return 1;
+ mode = drm_mode_analog_pal_576i(connector->dev);
+ if (!mode) {
+ DRM_ERROR("Failed to create a new display mode\n");
+ return -ENOMEM;
+ }
+
+ drm_mode_probed_add(connector, mode);
+
+ return 2;
+}
>>>
>>> Referencing those previous discussions:
>>> -
>>> https://lore.kernel.org/dri-devel/0255f7c6-0484-6456-350d-cf24f3fee...@tronnes.org/
>>> -
>>> https://lore.kernel.org/dri-devel/c8f8015a-75da-afa8-ca7f-b2b134cac...@gmail.com/
>>>
>>> Unconditionally setting the 480i mode as DRM_MODE_TYPE_PREFERRED causes Xorg
>>> (at least on current Raspberry Pi OS) to display garbage when
>>> video=Composite1:PAL is specified on the command line, so I'm afraid this
>>> won't
>>> do.
>>>
>>> As I see it, there are three viable solutions for this issue:
>>>
>>> a) Somehow query the video= command line option from this function, and set
>>>DRM_MODE_TYPE_PREFERRED appropriately. This would break the abstraction
>>>provided by global DRM code, but should work fine.
>>>
>>> b) Modify drm_helper_probe_add_cmdline_mode() so that it sets
>>>DRM_MODE_TYPE_PREFERRED in addition to DRM_MODE_TYPE_USERDEF. This seems
>>>pretty robust, but affects the entire DRM subsystem, which may break
>>>userspace in different ways.
>>>
>>>- Maybe this could be mitigated by adding some additional conditions,
>>> e.g.
>>> setting the PREFERRED flag only if no modes are already flagged as such
>>> and/or only if the cmdline mode is a named one (~= analog TV mode)
>>>
>>> c) Forcing userspace (Xorg / Raspberry Pi OS) to get fixed and honor the
>>> USERDEF
>>>flag.
>>>
>>> Either way, hardcoding 480i as PREFERRED does not seem right.
>>>
>>
>> My solution for this is to look at tv.mode to know which mode to mark as
>> preferred. Maxime didn't like this since it changes things behind
>> userspace's back. I don't see how that can cause any problems for userspace.
>>
>> If userspace uses atomic and sets tv_mode, it has to know which mode to
>> use before hand, so it doesn't look at the preferreded flag.
>>
>> If it uses legacy and sets tv_mode, it can end up with a stale preferred
>> flag, but no worse than not having the flag or that ntsc is always
>> preferred.
>>
>> If it doesn't change tv_mode, there's no problem, the preferred flag
>> doesn't change.
>
> I don't like it because I just see no way to make this reliable. When we
> set tv_mode, we're not only going to change the preferred flag, but also
> the order of the modes to make the preferred mode first.
>
> Since we just changed the mode lists, we also want to send a hotplug
> event to userspace so that it gets notified of it. It will pick up the
> new preferred mode, great.
>
> But what if it doesn't? There's no requirement for userspace to handle
> hotplug events, and Kodi won't for example. So we just changed the TV
> mode but not the actual mode, and that's it. It's just as broken for
> Kodi as it is for X11 right now.
>
> If we can't get a bullet-proof solution, then I'm not convinced it's
> worth addressing. Especially since it's already the current state, and
> it doesn't seem to bother a lot of people.
I wouldn't rely on the "doesn't seem to bother a lot of people" bit too much.
Here's why:
- Analog TV output is a relatively obscure feature in this day and age in the
first place.
- Out of the people interested in using it with VC4/VEC, many are actually using
the downstream kernel from https://github.com/raspberrypi/linux instead of the
upstream kernel, and/or firmware mode-switching instead of proper KMS.
- The downstream kernel only reports modes that match the TV mode set at boot
either via vc4.tv_norm=, or implied by the resolution set via video=; note
that video= is also set appropriately at boot by Pi firmware, based on the
value of sdtv_mode set in config.txt. See also the
vc4_vec_connector_get_modes() and vc4_vec_get_default_mode() functions in
https://github.com/raspberrypi/linux/blob/dbd073e4028580a09b6ee507e0c137441cb52650/drivers/gpu/drm/vc4/vc4_vec.c
- When firmware mode-switching is used, it sets the appropriate TV mode
Re: [Intel-gfx] [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
On Mon, Oct 17, 2022 at 12:31:31PM +0200, Noralf Trønnes wrote:
> Den 16.10.2022 20.52, skrev Mateusz Kwiatkowski:
> >> static int vc4_vec_connector_get_modes(struct drm_connector *connector)
> >> {
> >> - struct drm_connector_state *state = connector->state;
> >>struct drm_display_mode *mode;
> >>
> >> - mode = drm_mode_duplicate(connector->dev,
> >> -vc4_vec_tv_modes[state->tv.legacy_mode].mode);
> >> + mode = drm_mode_analog_ntsc_480i(connector->dev);
> >>if (!mode) {
> >>DRM_ERROR("Failed to create a new display mode\n");
> >>return -ENOMEM;
> >>}
> >>
> >> + mode->type |= DRM_MODE_TYPE_PREFERRED;
> >>drm_mode_probed_add(connector, mode);
> >>
> >> - return 1;
> >> + mode = drm_mode_analog_pal_576i(connector->dev);
> >> + if (!mode) {
> >> + DRM_ERROR("Failed to create a new display mode\n");
> >> + return -ENOMEM;
> >> + }
> >> +
> >> + drm_mode_probed_add(connector, mode);
> >> +
> >> + return 2;
> >> +}
> >
> > Referencing those previous discussions:
> > -
> > https://lore.kernel.org/dri-devel/0255f7c6-0484-6456-350d-cf24f3fee...@tronnes.org/
> > -
> > https://lore.kernel.org/dri-devel/c8f8015a-75da-afa8-ca7f-b2b134cac...@gmail.com/
> >
> > Unconditionally setting the 480i mode as DRM_MODE_TYPE_PREFERRED causes Xorg
> > (at least on current Raspberry Pi OS) to display garbage when
> > video=Composite1:PAL is specified on the command line, so I'm afraid this
> > won't
> > do.
> >
> > As I see it, there are three viable solutions for this issue:
> >
> > a) Somehow query the video= command line option from this function, and set
> >DRM_MODE_TYPE_PREFERRED appropriately. This would break the abstraction
> >provided by global DRM code, but should work fine.
> >
> > b) Modify drm_helper_probe_add_cmdline_mode() so that it sets
> >DRM_MODE_TYPE_PREFERRED in addition to DRM_MODE_TYPE_USERDEF. This seems
> >pretty robust, but affects the entire DRM subsystem, which may break
> >userspace in different ways.
> >
> >- Maybe this could be mitigated by adding some additional conditions,
> > e.g.
> > setting the PREFERRED flag only if no modes are already flagged as such
> > and/or only if the cmdline mode is a named one (~= analog TV mode)
> >
> > c) Forcing userspace (Xorg / Raspberry Pi OS) to get fixed and honor the
> > USERDEF
> >flag.
> >
> > Either way, hardcoding 480i as PREFERRED does not seem right.
> >
>
> My solution for this is to look at tv.mode to know which mode to mark as
> preferred. Maxime didn't like this since it changes things behind
> userspace's back. I don't see how that can cause any problems for userspace.
>
> If userspace uses atomic and sets tv_mode, it has to know which mode to
> use before hand, so it doesn't look at the preferreded flag.
>
> If it uses legacy and sets tv_mode, it can end up with a stale preferred
> flag, but no worse than not having the flag or that ntsc is always
> preferred.
>
> If it doesn't change tv_mode, there's no problem, the preferred flag
> doesn't change.
I don't like it because I just see no way to make this reliable. When we
set tv_mode, we're not only going to change the preferred flag, but also
the order of the modes to make the preferred mode first.
Since we just changed the mode lists, we also want to send a hotplug
event to userspace so that it gets notified of it. It will pick up the
new preferred mode, great.
But what if it doesn't? There's no requirement for userspace to handle
hotplug events, and Kodi won't for example. So we just changed the TV
mode but not the actual mode, and that's it. It's just as broken for
Kodi as it is for X11 right now.
If we can't get a bullet-proof solution, then I'm not convinced it's
worth addressing. Especially since it's already the current state, and
it doesn't seem to bother a lot of people.
Maxime
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Re: [Intel-gfx] [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
Hi Maxime,
Urgh. I cannot send e-mails apparently today, as I removed the second half of
the previous message. Here goes:
> @@ -454,13 +563,6 @@ static int vc4_vec_encoder_atomic_check(struct
> drm_encoder *encoder,
> struct drm_connector_state *conn_state)
> {
> const struct drm_display_mode *mode = &crtc_state->adjusted_mode;
You could add here something like:
+ const struct vc4_vec_tv_mode *tv_mode =
+ vc4_vec_tv_mode_lookup(conn_state->tv.mode);
+
+ if (!tv_mode)
+ return -EINVAL;
This should explicitly make it impossible to enter the equivalent condition in
vc4_vec_encoder_enable() that causes the problem mentioned in the previous
e-mail.
This is probably basically impossible already, but I triggered that when testing
a follow-up change I'd like to post shortly.
> - const struct vc4_vec_tv_mode *vec_mode;
> -
> - vec_mode = &vc4_vec_tv_modes[conn_state->tv.legacy_mode];
> -
> - if (conn_state->crtc &&
> - !drm_mode_equal(vec_mode->mode, &crtc_state->adjusted_mode))
> - return -EINVAL;
If you're removing the reference mode, then I think you should at least add
checks that the crtc_clock is set to 13.5 MHz (it's otherwise ignored) and that
crtc_htotal is either 858 or 864 (using a switch over reference_mode->htotal as
I proposed in my comment to patch 19/22 would double as such check), as all
other values causes VEC to output garbage.
Best regards,
Mateusz Kwiatkowski
Re: [Intel-gfx] [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
Hi Maxime,
> static int vc4_vec_connector_get_modes(struct drm_connector *connector)
> {
> - struct drm_connector_state *state = connector->state;
> struct drm_display_mode *mode;
>
> - mode = drm_mode_duplicate(connector->dev,
> - vc4_vec_tv_modes[state->tv.legacy_mode].mode);
> + mode = drm_mode_analog_ntsc_480i(connector->dev);
> if (!mode) {
> DRM_ERROR("Failed to create a new display mode\n");
> return -ENOMEM;
> }
>
> + mode->type |= DRM_MODE_TYPE_PREFERRED;
> drm_mode_probed_add(connector, mode);
>
> - return 1;
> + mode = drm_mode_analog_pal_576i(connector->dev);
> + if (!mode) {
> + DRM_ERROR("Failed to create a new display mode\n");
> + return -ENOMEM;
> + }
> +
> + drm_mode_probed_add(connector, mode);
> +
> + return 2;
> +}
Referencing those previous discussions:
-
https://lore.kernel.org/dri-devel/0255f7c6-0484-6456-350d-cf24f3fee...@tronnes.org/
-
https://lore.kernel.org/dri-devel/c8f8015a-75da-afa8-ca7f-b2b134cac...@gmail.com/
Unconditionally setting the 480i mode as DRM_MODE_TYPE_PREFERRED causes Xorg
(at least on current Raspberry Pi OS) to display garbage when
video=Composite1:PAL is specified on the command line, so I'm afraid this won't
do.
As I see it, there are three viable solutions for this issue:
a) Somehow query the video= command line option from this function, and set
DRM_MODE_TYPE_PREFERRED appropriately. This would break the abstraction
provided by global DRM code, but should work fine.
b) Modify drm_helper_probe_add_cmdline_mode() so that it sets
DRM_MODE_TYPE_PREFERRED in addition to DRM_MODE_TYPE_USERDEF. This seems
pretty robust, but affects the entire DRM subsystem, which may break
userspace in different ways.
- Maybe this could be mitigated by adding some additional conditions, e.g.
setting the PREFERRED flag only if no modes are already flagged as such
and/or only if the cmdline mode is a named one (~= analog TV mode)
c) Forcing userspace (Xorg / Raspberry Pi OS) to get fixed and honor the USERDEF
flag.
Either way, hardcoding 480i as PREFERRED does not seem right.
Note: this also applies to the sun4i version (patch 22/22).
> @@ -366,13 +472,16 @@ static void vc4_vec_encoder_enable(struct drm_encoder
> *encoder,
> struct drm_connector *connector = &vec->connector;
> struct drm_connector_state *conn_state =
> drm_atomic_get_new_connector_state(state, connector);
> - const struct vc4_vec_tv_mode *tv_mode =
> - &vc4_vec_tv_modes[conn_state->tv.legacy_mode];
> + const struct vc4_vec_tv_mode *tv_mode;
> int idx, ret;
>
> if (!drm_dev_enter(drm, &idx))
> return;
>
> + tv_mode = vc4_vec_tv_mode_lookup(conn_state->tv.mode);
> + if (!tv_mode)
> + goto err_dev_exit;
> +
> ret = pm_runtime_get_sync(&vec->pdev->dev);
> if (ret < 0) {
> DRM_ERROR("Failed to retain power domain: %d\n", ret);
If this (!tv_mode) condition is somehow triggered, the power management goes
somewhat crazy. vc4_vec_encoder_enable() cannot return an error, so when
vc4_vec_encoder_disable() is eventually called after a failed enable, it hangs
in pm_runtime_put() for quite a bit.
At least I think that's what's happening. Anyway, to solve this, I'd propose
this thing below:
Best regards,
Mateusz Kwiatkowski
Re: [Intel-gfx] [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
Den 13.10.2022 15.19, skrev Maxime Ripard:
> Now that the core can deal fine with analog TV modes, let's convert the vc4
> VEC driver to leverage those new features.
>
> We've added some backward compatibility to support the old TV mode property
> and translate it into the new TV norm property. We're also making use of
> the new analog TV atomic_check helper to make sure we trigger a modeset
> whenever the TV mode is updated.
>
> Acked-by: Noralf Trønnes
> Signed-off-by: Maxime Ripard
>
> ---
> @@ -276,19 +292,96 @@ static void vc4_vec_connector_reset(struct
> drm_connector *connector)
>
> static int vc4_vec_connector_get_modes(struct drm_connector *connector)
> {
> - struct drm_connector_state *state = connector->state;
> struct drm_display_mode *mode;
>
> - mode = drm_mode_duplicate(connector->dev,
> - vc4_vec_tv_modes[state->tv.legacy_mode].mode);
> + mode = drm_mode_analog_ntsc_480i(connector->dev);
> if (!mode) {
> DRM_ERROR("Failed to create a new display mode\n");
> return -ENOMEM;
> }
>
> + mode->type |= DRM_MODE_TYPE_PREFERRED;
> drm_mode_probed_add(connector, mode);
>
> - return 1;
> + mode = drm_mode_analog_pal_576i(connector->dev);
> + if (!mode) {
> + DRM_ERROR("Failed to create a new display mode\n");
> + return -ENOMEM;
I just remembered that you can't return an error from .get_modes, it
should only return the number of modes added. From doc:
* RETURNS:
*
* The number of modes added by calling drm_mode_probed_add().
See also the use of count in drm_helper_probe_single_connector_modes().
Patch 14 and 22 has the same issue.
Noralf.
> + }
> +
> + drm_mode_probed_add(connector, mode);
> +
> + return 2;
> +}
> +
> +static int
> +vc4_vec_connector_set_property(struct drm_connector *connector,
> +struct drm_connector_state *state,
> +struct drm_property *property,
> +uint64_t val)
> +{
> + struct vc4_vec *vec = connector_to_vc4_vec(connector);
> +
> + if (property != vec->legacy_tv_mode_property)
> + return -EINVAL;
> +
> + switch (val) {
> + case VC4_VEC_TV_MODE_NTSC:
> + state->tv.mode = DRM_MODE_TV_MODE_NTSC;
> + break;
> +
> + case VC4_VEC_TV_MODE_NTSC_J:
> + state->tv.mode = DRM_MODE_TV_MODE_NTSC_J;
> + break;
> +
> + case VC4_VEC_TV_MODE_PAL:
> + state->tv.mode = DRM_MODE_TV_MODE_PAL;
> + break;
> +
> + case VC4_VEC_TV_MODE_PAL_M:
> + state->tv.mode = DRM_MODE_TV_MODE_PAL_M;
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int
> +vc4_vec_connector_get_property(struct drm_connector *connector,
> +const struct drm_connector_state *state,
> +struct drm_property *property,
> +uint64_t *val)
> +{
> + struct vc4_vec *vec = connector_to_vc4_vec(connector);
> +
> + if (property != vec->legacy_tv_mode_property)
> + return -EINVAL;
> +
> + switch (state->tv.mode) {
> + case DRM_MODE_TV_MODE_NTSC:
> + *val = VC4_VEC_TV_MODE_NTSC;
> + break;
> +
> + case DRM_MODE_TV_MODE_NTSC_J:
> + *val = VC4_VEC_TV_MODE_NTSC_J;
> + break;
> +
> + case DRM_MODE_TV_MODE_PAL:
> + *val = VC4_VEC_TV_MODE_PAL;
> + break;
> +
> + case DRM_MODE_TV_MODE_PAL_M:
> + *val = VC4_VEC_TV_MODE_PAL_M;
> + break;
> +
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> }
>
> static const struct drm_connector_funcs vc4_vec_connector_funcs = {
> @@ -297,15 +390,19 @@ static const struct drm_connector_funcs
> vc4_vec_connector_funcs = {
> .reset = vc4_vec_connector_reset,
> .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> + .atomic_get_property = vc4_vec_connector_get_property,
> + .atomic_set_property = vc4_vec_connector_set_property,
> };
>
> static const struct drm_connector_helper_funcs
> vc4_vec_connector_helper_funcs = {
> + .atomic_check = drm_atomic_helper_connector_tv_check,
> .get_modes = vc4_vec_connector_get_modes,
> };
>
> static int vc4_vec_connector_init(struct drm_device *dev, struct vc4_vec
> *vec)
> {
> struct drm_connector *connector = &vec->connector;
> + struct drm_property *prop;
> int ret;
>
> connector->interlace_allowed = true;
> @@ -318,8 +415,17 @@ static int vc4_vec_connector_init(struct drm_device
> *dev, struct vc4_vec *vec)
> drm_connector_helper_add(connector, &vc4_vec_connector_helper_funcs);
>
> drm_objec
Re: [Intel-gfx] [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
Den 16.10.2022 20.52, skrev Mateusz Kwiatkowski:
> Hi Maxime,
>
>> static int vc4_vec_connector_get_modes(struct drm_connector *connector)
>> {
>> -struct drm_connector_state *state = connector->state;
>> struct drm_display_mode *mode;
>>
>> -mode = drm_mode_duplicate(connector->dev,
>> - vc4_vec_tv_modes[state->tv.legacy_mode].mode);
>> +mode = drm_mode_analog_ntsc_480i(connector->dev);
>> if (!mode) {
>> DRM_ERROR("Failed to create a new display mode\n");
>> return -ENOMEM;
>> }
>>
>> +mode->type |= DRM_MODE_TYPE_PREFERRED;
>> drm_mode_probed_add(connector, mode);
>>
>> -return 1;
>> +mode = drm_mode_analog_pal_576i(connector->dev);
>> +if (!mode) {
>> +DRM_ERROR("Failed to create a new display mode\n");
>> +return -ENOMEM;
>> +}
>> +
>> +drm_mode_probed_add(connector, mode);
>> +
>> +return 2;
>> +}
>
> Referencing those previous discussions:
> -
> https://lore.kernel.org/dri-devel/0255f7c6-0484-6456-350d-cf24f3fee...@tronnes.org/
> -
> https://lore.kernel.org/dri-devel/c8f8015a-75da-afa8-ca7f-b2b134cac...@gmail.com/
>
> Unconditionally setting the 480i mode as DRM_MODE_TYPE_PREFERRED causes Xorg
> (at least on current Raspberry Pi OS) to display garbage when
> video=Composite1:PAL is specified on the command line, so I'm afraid this
> won't
> do.
>
> As I see it, there are three viable solutions for this issue:
>
> a) Somehow query the video= command line option from this function, and set
>DRM_MODE_TYPE_PREFERRED appropriately. This would break the abstraction
>provided by global DRM code, but should work fine.
>
> b) Modify drm_helper_probe_add_cmdline_mode() so that it sets
>DRM_MODE_TYPE_PREFERRED in addition to DRM_MODE_TYPE_USERDEF. This seems
>pretty robust, but affects the entire DRM subsystem, which may break
>userspace in different ways.
>
>- Maybe this could be mitigated by adding some additional conditions, e.g.
> setting the PREFERRED flag only if no modes are already flagged as such
> and/or only if the cmdline mode is a named one (~= analog TV mode)
>
> c) Forcing userspace (Xorg / Raspberry Pi OS) to get fixed and honor the
> USERDEF
>flag.
>
> Either way, hardcoding 480i as PREFERRED does not seem right.
>
My solution for this is to look at tv.mode to know which mode to mark as
preferred. Maxime didn't like this since it changes things behind
userspace's back. I don't see how that can cause any problems for userspace.
If userspace uses atomic and sets tv_mode, it has to know which mode to
use before hand, so it doesn't look at the preferreded flag.
If it uses legacy and sets tv_mode, it can end up with a stale preferred
flag, but no worse than not having the flag or that ntsc is always
preferred.
If it doesn't change tv_mode, there's no problem, the preferred flag
doesn't change.
Noralf.
