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Message-ID: <0f5908be-5dca-4590-b931-2a9fc8963f93@linux.dev>
Date: Sun, 9 Feb 2025 18:00:19 +0530
From: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
To: Jayesh Choudhary <j-choudhary@...com>,
Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Andrzej Hajda <andrzej.hajda@...el.com>,
Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: Nishanth Menon <nm@...com>, Vignesh Raghavendra <vigneshr@...com>,
Devarsh Thakkar <devarsht@...com>, Praneeth Bajjuri <praneeth@...com>,
Udit Kumar <u-kumar1@...com>,
DRI Development List <dri-devel@...ts.freedesktop.org>,
Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 11/13] drm/atomic-helper: Separate out bridge
pre_enable/post_disable from enable/disable
Hi Jayesh,
Thank you for testing this out, and reporting the error I had
overlooked.
On 04/02/25 17:59, Jayesh Choudhary wrote:
> Hello Aradhya,
>
> On 27/01/25 00:45, Aradhya Bhatia wrote:
>> The encoder-bridge ops occur by looping over the new connector states of
>> the display pipelines. The enable sequence runs as follows -
>>
>> - pre_enable(bridge),
>> - enable(encoder),
>> - enable(bridge),
>>
>> while the disable sequnce runs as follows -
>>
>> - disable(bridge),
>> - disable(encoder),
>> - post_disable(bridge).
>>
>> Separate out the pre_enable(bridge), and the post_disable(bridge)
>> operations into separate functions each.
>>
>> This patch keeps the sequence same for any singular disaplay pipe, but
>> changes the sequence across multiple display pipelines.
>>
>> This patch is meant to be an interim patch, to cleanly pave the way for
>> the sequence re-ordering patch, and maintain bisectability in the
>> process.
>>
>> Signed-off-by: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
>> ---
>> drivers/gpu/drm/drm_atomic_helper.c | 92 +++++++++++++++++++++++++++--
>> 1 file changed, 88 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/
>> drm_atomic_helper.c
>> index e805fd0a54c5..f5532e3646e1 100644
>> --- a/drivers/gpu/drm/drm_atomic_helper.c
>> +++ b/drivers/gpu/drm/drm_atomic_helper.c
>> @@ -1185,8 +1185,6 @@ encoder_bridge_disable(struct drm_device *dev,
>> struct drm_atomic_state *old_stat
>> else if (funcs->dpms)
>> funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
>> }
>> -
>> - drm_atomic_bridge_chain_post_disable(bridge, old_state);
>> }
>> }
>> @@ -1243,11 +1241,65 @@ crtc_disable(struct drm_device *dev, struct
>> drm_atomic_state *old_state)
>> }
>> }
>> +static void
>> +encoder_bridge_post_disable(struct drm_device *dev, struct
>> drm_atomic_state *old_state)
>> +{
>> + struct drm_connector *connector;
>> + struct drm_connector_state *old_conn_state, *new_conn_state;
>> + struct drm_crtc_state *old_crtc_state, *new_crtc_state;
>> + int i;
>> +
>> + for_each_oldnew_connector_in_state(old_state, connector,
>> old_conn_state, new_conn_state, i) {
>> + struct drm_encoder *encoder;
>> + struct drm_bridge *bridge;
>> +
>> + /*
>> + * Shut down everything that's in the changeset and currently
>> + * still on. So need to check the old, saved state.
>> + */
>> + if (!old_conn_state->crtc)
>> + continue;
>> +
>> + old_crtc_state = drm_atomic_get_old_crtc_state(old_state,
>> old_conn_state->crtc);
>> +
>> + if (new_conn_state->crtc)
>> + new_crtc_state = drm_atomic_get_new_crtc_state(
>> + old_state,
>> + new_conn_state->crtc);
>> + else
>> + new_crtc_state = NULL;
>> +
>> + if (!crtc_needs_disable(old_crtc_state, new_crtc_state) ||
>> + !drm_atomic_crtc_needs_modeset(old_conn_state->crtc->state))
>> + continue;
>> +
>> + encoder = old_conn_state->best_encoder;
>> +
>> + /* We shouldn't get this far if we didn't previously have
>> + * an encoder.. but WARN_ON() rather than explode.
>> + */
>> + if (WARN_ON(!encoder))
>> + continue;
>> +
>> + drm_dbg_atomic(dev, "post-disabling bridges [ENCODER:%d:%s]\n",
>> + encoder->base.id, encoder->name);
>> +
>> + /*
>> + * Each encoder has at most one connector (since we always steal
>> + * it away), so we won't call disable hooks twice.
>> + */
>> + bridge = drm_bridge_chain_get_first_bridge(encoder);
>> + drm_atomic_bridge_chain_post_disable(bridge, old_state);
>> + }
>> +}
>> +
>> static void
>> disable_outputs(struct drm_device *dev, struct drm_atomic_state
>> *old_state)
>> {
>> encoder_bridge_disable(dev, old_state);
>> + encoder_bridge_post_disable(dev, old_state);
>> +
>> crtc_disable(dev, old_state);
>> }
>> @@ -1460,6 +1512,38 @@ static void
>> drm_atomic_helper_commit_writebacks(struct drm_device *dev,
>> }
>> }
>> +static void
>> +encoder_bridge_pre_enable(struct drm_device *dev, struct
>> drm_atomic_state *old_state)
>> +{
>> + struct drm_connector *connector;
>> + struct drm_connector_state *new_conn_state;
>> + int i;
>> +
>> + for_each_new_connector_in_state(old_state, connector,
>> new_conn_state, i) {
>> + struct drm_encoder *encoder;
>> + struct drm_bridge *bridge;
>> +
>> + if (!new_conn_state->best_encoder)
>> + continue;
>> +
>> + if (!new_conn_state->crtc->state->active ||
>> + !drm_atomic_crtc_needs_modeset(new_conn_state->crtc->state))
>> + continue;
>> +
>> + encoder = new_conn_state->best_encoder;
>> +
>> + drm_dbg_atomic(dev, "pre-enabling bridges [ENCODER:%d:%s]\n",
>> + encoder->base.id, encoder->name);
>> +
>> + /*
>> + * Each encoder has at most one connector (since we always steal
>> + * it away), so we won't call enable hooks twice.
>> + */
>> + bridge = drm_bridge_chain_get_first_bridge(encoder);
>> + drm_atomic_bridge_chain_pre_enable(bridge, old_state);
>> + }
>> +}
>> +
>> static void
>> crtc_enable(struct drm_device *dev, struct drm_atomic_state *old_state)
>> {
>> @@ -1531,8 +1615,6 @@ encoder_bridge_enable(struct drm_device *dev,
>> struct drm_atomic_state *old_state
>> else if (funcs->commit)
>> funcs->commit(encoder);
>> }
>> -
>> - drm_atomic_bridge_chain_enable(bridge, old_state);
>> }
>> }
>> @@ -1555,6 +1637,8 @@ void
>> drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
>> {
>> crtc_enable(dev, old_state);
>> + encoder_bridge_pre_enable(dev, old_state);
>> +
>> encoder_bridge_enable(dev, old_state);
>>
>
> After separating enable and pre_enable, bridge_chain_enable hook is not
> called. This breaks display.
That is true.
>
> In encoder_bridge_enable call, you need to call
> bridge_chain_enable call instead of bridge_chain_pre_enable.
Yes, the encoder_bridge_enable() is supposed to call
bridge_chain_enable() instead of bridge_chain_pre_enable().
>
>
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/
> drm_atomic_helper.c
> index d2f19df9f418..1b580dc068bf 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1605,7 +1605,7 @@ encoder_bridge_enable(struct drm_device *dev,
> struct drm_atomic_state *old_state
> * it away), so we won't call enable hooks twice.
> */
> bridge = drm_bridge_chain_get_first_bridge(encoder);
> - drm_atomic_bridge_chain_pre_enable(bridge, old_state);
> + drm_atomic_bridge_chain_enable(bridge, old_state);
While your report is right, I couldn't take this diff as is. The
bridge_chain_enable has to still happen _after_ all the encoders are
enabled inside this function (unlike the bridge_chain_pre_enable that
would happen before the encoder_enable).
>
> if (funcs) {
> if (funcs->atomic_enable)
>
> I have tested display on J784S4-EVM for MHDP and DSI with this diff on
> top of your series.
>
> With the above change addressed,
>
> Reviewed-by: Jayesh Choudhary <j-choudhary@...com>
Thank you!
I have posted the patch[0], and I have taken the liberty to accept the
tag despite the change in the way I have fixed the error. If that is
unacceptable, please do let me know and I will remove it in a newer
revision.
--
Regards
Aradhya
[0]: [PATCH v9 11/13] drm/atomic-helper: Separate out bridge pre_enable/
post_disable from enable/disable
https://lore.kernel.org/all/20250209121621.34677-4-aradhya.bhatia@linux.dev/
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