Message-ID: <009fbf0a-f79e-1708-f2ed-66a55cb1e95e@codeaurora.org>
Date:   Sat, 15 Oct 2016 14:40:04 +0530
From:   Archit Taneja <architt@...eaurora.org>
To:     Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        dri-devel@...ts.freedesktop.org
Cc:     linux-kernel@...r.kernel.org, airlied@...ux.ie,
        linux-snps-arc@...ts.infradead.org, Alexey.Brodkin@...opsys.com
Subject: Re: [PATCH] drm/arcpgu: Accommodate adv7511 switch to DRM bridge

Hi,

On 10/14/2016 6:57 PM, Eugeniy Paltsev wrote:
> ARC PGU driver starts crashing on initialization after
> 'commit e12c2f645557 ("drm/i2c: adv7511: Convert to drm_bridge")'
> This happenes because in "arcpgu_drm_hdmi_init" function we get pointer
> of "drm_i2c_encoder_driver" structure, which doesn't exist after
> adv7511 hdmi encoder interface changed from slave encoder to drm bridge.
> So, when we call "encoder_init" function from this structure driver
> crashes.
>

The conversion doesn't seem entirely correct. Some comments below.


> Bootlog:
> ------------------------------------->8--------------------------------
> [drm] Initialized drm 1.1.0 20060810
> arcpgu e0017000.pgu: arc_pgu ID: 0xabbabaab
> arcpgu e0017000.pgu: assigned reserved memory node frame_buffer@...00000
> Path: (null)
> CPU: 0 PID: 1 Comm: swapper Not tainted 4.8.0-00001-gb5642252fa01-dirty #8
> task: 9a058000 task.stack: 9a032000
>
> [ECR   ]: 0x00220100 => Invalid Read @ 0x00000004 by insn @ 0x803934e8
> [EFA   ]: 0x00000004
> [BLINK ]: drm_atomic_helper_connector_dpms+0xa6/0x230
> [ERET  ]: drm_atomic_helper_connector_dpms+0xa4/0x230
> [STAT32]: 0x00000846 : K DE       E2 E1
> BTA: 0x8016d949  SP: 0x9a033e34  FP: 0x00000000
> LPS: 0x8036f6fc LPE: 0x8036f700 LPC: 0x00000000
> r00: 0x8063c118 r01: 0x805b98ac r02: 0x00000b11
> r03: 0x00000000 r04: 0x9a010f54 r05: 0x00000000
> r06: 0x00000001 r07: 0x00000000 r08: 0x00000028
> r09: 0x00000001 r10: 0x00000007 r11: 0x00000054
> r12: 0x720a3033
>
> Stack Trace:
>   drm_atomic_helper_connector_dpms+0xa4/0x230
>   arcpgu_drm_hdmi_init+0xbc/0x228
>   arcpgu_probe+0x168/0x244
>   platform_drv_probe+0x26/0x64
>   really_probe+0x1f0/0x32c
>   __driver_attach+0xa8/0xd0
>   bus_for_each_dev+0x3c/0x74
>   bus_add_driver+0xc2/0x184
>   driver_register+0x50/0xec
>   do_one_initcall+0x3a/0x120
>   kernel_init_freeable+0x108/0x1a0
> ------------------------------------->8--------------------------------
>
> Fix ARC PGU driver to be able work with drm bridge hdmi encoder
> interface. The hdmi connector code isn't needed anymore as we expect
> the adv7511 bridge driver to create/manage the connector.
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
> ---
>  drivers/gpu/drm/arc/arcpgu_hdmi.c | 144 +++++++++-----------------------------
>  1 file changed, 35 insertions(+), 109 deletions(-)
>
> diff --git a/drivers/gpu/drm/arc/arcpgu_hdmi.c b/drivers/gpu/drm/arc/arcpgu_hdmi.c
> index b7a8b2a..48a6c63 100644
> --- a/drivers/gpu/drm/arc/arcpgu_hdmi.c
> +++ b/drivers/gpu/drm/arc/arcpgu_hdmi.c
> @@ -14,104 +14,54 @@
>   *
>   */
>
> +#include <drm/drm_crtc.h>
>  #include <drm/drm_crtc_helper.h>
>  #include <drm/drm_encoder_slave.h>
>  #include <drm/drm_atomic_helper.h>
>
>  #include "arcpgu.h"
>
> -struct arcpgu_drm_connector {
> -	struct drm_connector connector;
> -	struct drm_encoder_slave *encoder_slave;
> -};
> -
> -static int arcpgu_drm_connector_get_modes(struct drm_connector *connector)
> +static void arcpgu_drm_i2c_encoder_mode_set(struct drm_encoder *encoder,
> +				struct drm_display_mode *mode,
> +				struct drm_display_mode *adjusted_mode)
>  {
> -	const struct drm_encoder_slave_funcs *sfuncs;
> -	struct drm_encoder_slave *slave;
> -	struct arcpgu_drm_connector *con =
> -		container_of(connector, struct arcpgu_drm_connector, connector);
> -
> -	slave = con->encoder_slave;
> -	if (slave == NULL) {
> -		dev_err(connector->dev->dev,
> -			"connector_get_modes: cannot find slave encoder for connector\n");
> -		return 0;
> -	}
> -
> -	sfuncs = slave->slave_funcs;
> -	if (sfuncs->get_modes == NULL)
> -		return 0;
> -
> -	return sfuncs->get_modes(&slave->base, connector);
> -}
> -
> -static enum drm_connector_status
> -arcpgu_drm_connector_detect(struct drm_connector *connector, bool force)
> -{
> -	enum drm_connector_status status = connector_status_unknown;
> -	const struct drm_encoder_slave_funcs *sfuncs;
> -	struct drm_encoder_slave *slave;
> -
> -	struct arcpgu_drm_connector *con =
> -		container_of(connector, struct arcpgu_drm_connector, connector);
> -
> -	slave = con->encoder_slave;
> -	if (slave == NULL) {
> -		dev_err(connector->dev->dev,
> -			"connector_detect: cannot find slave encoder for connector\n");
> -		return status;
> -	}
> +	struct drm_bridge *bridge = encoder->bridge;
>
> -	sfuncs = slave->slave_funcs;
> -	if (sfuncs && sfuncs->detect)
> -		return sfuncs->detect(&slave->base, connector);
> -
> -	dev_err(connector->dev->dev, "connector_detect: could not detect slave funcs\n");
> -	return status;
> +	bridge->funcs->mode_set(bridge, mode, adjusted_mode);

The bridge functions shouldn't really be called by the kms driver.
They're called automatically by the drm core for the bridge attached
to the encoder. See mode_fixup in drivers/gpu/drm/drm_atomic_helper.c

>  }
>
> -static void arcpgu_drm_connector_destroy(struct drm_connector *connector)
> -{
> -	drm_connector_unregister(connector);
> -	drm_connector_cleanup(connector);
> -}
> -
> -static const struct drm_connector_helper_funcs
> -arcpgu_drm_connector_helper_funcs = {
> -	.get_modes = arcpgu_drm_connector_get_modes,
> -};
> -
> -static const struct drm_connector_funcs arcpgu_drm_connector_funcs = {
> -	.dpms = drm_helper_connector_dpms,
> -	.reset = drm_atomic_helper_connector_reset,
> -	.detect = arcpgu_drm_connector_detect,
> -	.fill_modes = drm_helper_probe_single_connector_modes,
> -	.destroy = arcpgu_drm_connector_destroy,
> -	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> -	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> -};
> -
>  static struct drm_encoder_helper_funcs arcpgu_drm_encoder_helper_funcs = {
>  	.dpms = drm_i2c_encoder_dpms,
>  	.mode_fixup = drm_i2c_encoder_mode_fixup,
> -	.mode_set = drm_i2c_encoder_mode_set,
> +	.mode_set = arcpgu_drm_i2c_encoder_mode_set,
>  	.prepare = drm_i2c_encoder_prepare,
>  	.commit = drm_i2c_encoder_commit,
> -	.detect = drm_i2c_encoder_detect,
>  };
>
>  static struct drm_encoder_funcs arcpgu_drm_encoder_funcs = {
>  	.destroy = drm_encoder_cleanup,
>  };
>
> +static void arcpgu_drm_i2c_encoder_dpms(struct drm_encoder *encoder, int mode)
> +{
> +	struct drm_bridge *bridge = encoder->bridge;
> +
> +	if (mode == DRM_MODE_DPMS_ON)
> +		bridge->funcs->enable(bridge);
> +	else
> +		bridge->funcs->disable(bridge);
> +}
> +
> +static struct drm_encoder_slave_funcs arcpgu_drm_encoder_slave_funcs = {
> +	.dpms = arcpgu_drm_i2c_encoder_dpms,
> +};
> +
>  int arcpgu_drm_hdmi_init(struct drm_device *drm, struct device_node *np)
>  {
> -	struct arcpgu_drm_connector *arcpgu_connector;
> -	struct drm_i2c_encoder_driver *driver;
>  	struct drm_encoder_slave *encoder;

We should get rid of the drm_encoder_slave interface here entirely. A
regular drm_encoder should be created here, with mostly noop funcs so
that it doesn't do anything and lets the bridge manage things.


> -	struct drm_connector *connector;
>  	struct i2c_client *i2c_slave;
> +	struct drm_bridge *bridge;
> +
>  	int ret;
>
>  	encoder = devm_kzalloc(drm->dev, sizeof(*encoder), GFP_KERNEL);
> @@ -129,16 +79,14 @@ int arcpgu_drm_hdmi_init(struct drm_device *drm, struct device_node *np)
>  		return -EPROBE_DEFER;
>  	}
>
> -	driver =
> -	    to_drm_i2c_encoder_driver(to_i2c_driver(i2c_slave->dev.driver));
> -	ret = driver->encoder_init(i2c_slave, drm, encoder);
> -	if (ret) {
> -		dev_err(drm->dev, "failed to initialize i2c encoder slave\n");
> -		return ret;
> -	}
> +	/* Locate drm bridge from the hdmi encoder DT node */
> +	bridge = of_drm_find_bridge(np);
> +	if (!bridge)
> +		return -EPROBE_DEFER;
>
>  	encoder->base.possible_crtcs = 1;
>  	encoder->base.possible_clones = 0;
> +	encoder->slave_funcs = &arcpgu_drm_encoder_slave_funcs;

This should go away too.

>  	ret = drm_encoder_init(drm, &encoder->base, &arcpgu_drm_encoder_funcs,
>  			       DRM_MODE_ENCODER_TMDS, NULL);
>  	if (ret)
> @@ -147,37 +95,15 @@ int arcpgu_drm_hdmi_init(struct drm_device *drm, struct device_node *np)
>  	drm_encoder_helper_add(&encoder->base,
>  			       &arcpgu_drm_encoder_helper_funcs);
>
> -	arcpgu_connector = devm_kzalloc(drm->dev, sizeof(*arcpgu_connector),
> -					GFP_KERNEL);
> -	if (!arcpgu_connector) {
> -		ret = -ENOMEM;
> -		goto error_encoder_cleanup;
> -	}
> +	/* Link drm_bridge to encoder */
> +	bridge->encoder = &encoder->base;

This will simply become "bridge->encoder = encoder;"

> +	encoder->base.bridge = bridge;

and this "encoder->bridge = bridge;"

You can have a look at the following patches which did the same
for rcar-du driver:

drm: rcar-du: Remove i2c slave encoder interface for hdmi encoder

and

drm: rcar-du: Link HDMI encoder with bridge

Thanks,
Archit

>
> -	connector = &arcpgu_connector->connector;
> -	drm_connector_helper_add(connector, &arcpgu_drm_connector_helper_funcs);
> -	ret = drm_connector_init(drm, connector, &arcpgu_drm_connector_funcs,
> -			DRM_MODE_CONNECTOR_HDMIA);
> -	if (ret < 0) {
> -		dev_err(drm->dev, "failed to initialize drm connector\n");
> -		goto error_encoder_cleanup;
> -	}
> -
> -	ret = drm_mode_connector_attach_encoder(connector, &encoder->base);
> -	if (ret < 0) {
> -		dev_err(drm->dev, "could not attach connector to encoder\n");
> -		drm_connector_unregister(connector);
> -		goto error_connector_cleanup;
> +	ret = drm_bridge_attach(drm, bridge);
> +	if (ret) {
> +		drm_encoder_cleanup(&encoder->base);
> +		return ret;
>  	}
>
> -	arcpgu_connector->encoder_slave = encoder;
> -
>  	return 0;
> -
> -error_connector_cleanup:
> -	drm_connector_cleanup(connector);
> -
> -error_encoder_cleanup:
> -	drm_encoder_cleanup(&encoder->base);
> -	return ret;
>  }
>

-- 
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