[PATCH v4 03/17] drm/dp: Add backpointer to drm_device in drm_dp_aux

From: Lyude Paul
Date: Fri Apr 23 2021 - 14:44:11 EST

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This is something that we've wanted for a while now: the ability to
actually look up the respective drm_device for a given drm_dp_aux struct.
This will also allow us to transition over to using the drm_dbg_*() helpers
for debug message printing, as we'll finally have a drm_device to reference
for doing so.

Note that there is one limitation with this - because some DP AUX adapters
exist as platform devices which are initialized independently of their
respective DRM devices, one cannot rely on drm_dp_aux->drm_dev to always be
non-NULL until drm_dp_aux_register() has been called. We make sure to point
this out in the documentation for struct drm_dp_aux.

v3:
* Add WARN_ON_ONCE() to drm_dp_aux_register() if drm_dev isn't filled out

Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Acked-by: Thierry Reding <treding@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/atombios_dp.c | 2 ++
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 1 +
drivers/gpu/drm/bridge/analogix/analogix-anx6345.c | 1 +
drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c | 1 +
drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 1 +
drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 1 +
drivers/gpu/drm/bridge/tc358767.c | 1 +
drivers/gpu/drm/bridge/ti-sn65dsi86.c | 1 +
drivers/gpu/drm/drm_dp_aux_dev.c | 6 ++++++
drivers/gpu/drm/drm_dp_helper.c | 2 ++
drivers/gpu/drm/drm_dp_mst_topology.c | 1 +
drivers/gpu/drm/i915/display/intel_dp_aux.c | 1 +
drivers/gpu/drm/msm/edp/edp.h | 3 +--
drivers/gpu/drm/msm/edp/edp_aux.c | 5 +++--
drivers/gpu/drm/msm/edp/edp_ctrl.c | 2 +-
drivers/gpu/drm/nouveau/nouveau_connector.c | 1 +
drivers/gpu/drm/radeon/atombios_dp.c | 1 +
drivers/gpu/drm/tegra/dpaux.c | 1 +
drivers/gpu/drm/xlnx/zynqmp_dp.c | 1 +
include/drm/drm_dp_helper.h | 9 ++++++++-
20 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
index a3ba9ca11e98..062625a8a4ec 100644
--- a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
@@ -188,6 +188,8 @@ void amdgpu_atombios_dp_aux_init(struct amdgpu_connector *amdgpu_connector)
{
amdgpu_connector->ddc_bus->rec.hpd = amdgpu_connector->hpd.hpd;
amdgpu_connector->ddc_bus->aux.transfer = amdgpu_atombios_dp_aux_transfer;
+ amdgpu_connector->ddc_bus->aux.drm_dev = amdgpu_connector->base.dev;
+
drm_dp_aux_init(&amdgpu_connector->ddc_bus->aux);
amdgpu_connector->ddc_bus->has_aux = true;
}
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 73cdb9fe981a..997567f6f0ba 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -433,6 +433,7 @@ void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
kasprintf(GFP_KERNEL, "AMDGPU DM aux hw bus %d",
link_index);
aconnector->dm_dp_aux.aux.transfer = dm_dp_aux_transfer;
+ aconnector->dm_dp_aux.aux.drm_dev = dm->ddev;
aconnector->dm_dp_aux.ddc_service = aconnector->dc_link->ddc;

drm_dp_aux_init(&aconnector->dm_dp_aux.aux);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
index aa6cda458eb9..e33cd077595a 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix-anx6345.c
@@ -537,6 +537,7 @@ static int anx6345_bridge_attach(struct drm_bridge *bridge,
/* Register aux channel */
anx6345->aux.name = "DP-AUX";
anx6345->aux.dev = &anx6345->client->dev;
+ anx6345->aux.drm_dev = bridge->dev;
anx6345->aux.transfer = anx6345_aux_transfer;

err = drm_dp_aux_register(&anx6345->aux);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
index f20558618220..5e6a0ed39199 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
@@ -905,6 +905,7 @@ static int anx78xx_bridge_attach(struct drm_bridge *bridge,
/* Register aux channel */
anx78xx->aux.name = "DP-AUX";
anx78xx->aux.dev = &anx78xx->client->dev;
+ anx78xx->aux.drm_dev = bridge->dev;
anx78xx->aux.transfer = anx78xx_aux_transfer;

err = drm_dp_aux_register(&anx78xx->aux);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index f115233b1cb9..550814ca2139 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1765,6 +1765,7 @@ int analogix_dp_bind(struct analogix_dp_device *dp, struct drm_device *drm_dev)
dp->aux.name = "DP-AUX";
dp->aux.transfer = analogix_dpaux_transfer;
dp->aux.dev = dp->dev;
+ dp->aux.drm_dev = drm_dev;

ret = drm_dp_aux_register(&dp->aux);
if (ret)
diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 49e4c340f1de..0cd8f40fb690 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -1719,6 +1719,7 @@ static int cdns_mhdp_attach(struct drm_bridge *bridge,

dev_dbg(mhdp->dev, "%s\n", __func__);

+ mhdp->aux.drm_dev = bridge->dev;
ret = drm_dp_aux_register(&mhdp->aux);
if (ret < 0)
return ret;
diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index da89922721ed..23a6f90b694b 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1414,6 +1414,7 @@ static int tc_bridge_attach(struct drm_bridge *bridge,
if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
return 0;

+ tc->aux.drm_dev = drm;
ret = drm_dp_aux_register(&tc->aux);
if (ret < 0)
return ret;
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 51db30d573c1..56706714561f 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -350,6 +350,7 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge,
return -EINVAL;
}

+ pdata->aux.drm_dev = bridge->dev;
ret = drm_dp_aux_register(&pdata->aux);
if (ret < 0) {
drm_err(bridge->dev, "Failed to register DP AUX channel: %d\n", ret);
diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c
index e25181bf2c48..06b374cae956 100644
--- a/drivers/gpu/drm/drm_dp_aux_dev.c
+++ b/drivers/gpu/drm/drm_dp_aux_dev.c
@@ -278,6 +278,12 @@ void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
if (!aux_dev) /* attach must have failed */
return;

+ /*
+ * As some AUX adapters may exist as platform devices which outlive their respective DRM
+ * devices, we clear drm_dev to ensure that we never accidentally reference a stale pointer
+ */
+ aux->drm_dev = NULL;
+
mutex_lock(&aux_idr_mutex);
idr_remove(&aux_idr, aux_dev->index);
mutex_unlock(&aux_idr_mutex);
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index cb2f53e56685..ad73d7264743 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -1767,6 +1767,8 @@ int drm_dp_aux_register(struct drm_dp_aux *aux)
{
int ret;

+ WARN_ON_ONCE(!aux->drm_dev);
+
if (!aux->ddc.algo)
drm_dp_aux_init(aux);

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 159014455fab..276f7f054d62 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2350,6 +2350,7 @@ drm_dp_mst_add_port(struct drm_device *dev,
port->aux.is_remote = true;

/* initialize the MST downstream port's AUX crc work queue */
+ port->aux.drm_dev = dev;
drm_dp_remote_aux_init(&port->aux);

/*
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
index 7e83bc2cc34a..c4b446d6a042 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -682,6 +682,7 @@ void intel_dp_aux_init(struct intel_dp *intel_dp)
else
intel_dp->get_aux_send_ctl = g4x_get_aux_send_ctl;

+ intel_dp->aux.drm_dev = &dev_priv->drm;
drm_dp_aux_init(&intel_dp->aux);

/* Failure to allocate our preferred name is not critical */
diff --git a/drivers/gpu/drm/msm/edp/edp.h b/drivers/gpu/drm/msm/edp/edp.h
index eb34243dad53..8590f2ce274d 100644
--- a/drivers/gpu/drm/msm/edp/edp.h
+++ b/drivers/gpu/drm/msm/edp/edp.h
@@ -46,8 +46,7 @@ void edp_bridge_destroy(struct drm_bridge *bridge);
struct drm_connector *msm_edp_connector_init(struct msm_edp *edp);

/* AUX */
-void *msm_edp_aux_init(struct device *dev, void __iomem *regbase,
- struct drm_dp_aux **drm_aux);
+void *msm_edp_aux_init(struct msm_edp *edp, void __iomem *regbase, struct drm_dp_aux **drm_aux);
void msm_edp_aux_destroy(struct device *dev, struct edp_aux *aux);
irqreturn_t msm_edp_aux_irq(struct edp_aux *aux, u32 isr);
void msm_edp_aux_ctrl(struct edp_aux *aux, int enable);
diff --git a/drivers/gpu/drm/msm/edp/edp_aux.c b/drivers/gpu/drm/msm/edp/edp_aux.c
index df10a0196d94..e3d85c622cfb 100644
--- a/drivers/gpu/drm/msm/edp/edp_aux.c
+++ b/drivers/gpu/drm/msm/edp/edp_aux.c
@@ -184,9 +184,9 @@ static ssize_t edp_aux_transfer(struct drm_dp_aux *drm_aux,
return ret;
}

-void *msm_edp_aux_init(struct device *dev, void __iomem *regbase,
- struct drm_dp_aux **drm_aux)
+void *msm_edp_aux_init(struct msm_edp *edp, void __iomem *regbase, struct drm_dp_aux **drm_aux)
{
+ struct device *dev = &edp->pdev->dev;
struct edp_aux *aux = NULL;
int ret;

@@ -201,6 +201,7 @@ void *msm_edp_aux_init(struct device *dev, void __iomem *regbase,

aux->drm_aux.name = "msm_edp_aux";
aux->drm_aux.dev = dev;
+ aux->drm_aux.drm_dev = edp->dev;
aux->drm_aux.transfer = edp_aux_transfer;
ret = drm_dp_aux_register(&aux->drm_aux);
if (ret) {
diff --git a/drivers/gpu/drm/msm/edp/edp_ctrl.c b/drivers/gpu/drm/msm/edp/edp_ctrl.c
index 0d9657cc70db..57af3d8b6699 100644
--- a/drivers/gpu/drm/msm/edp/edp_ctrl.c
+++ b/drivers/gpu/drm/msm/edp/edp_ctrl.c
@@ -1153,7 +1153,7 @@ int msm_edp_ctrl_init(struct msm_edp *edp)
}

/* Init aux and phy */
- ctrl->aux = msm_edp_aux_init(dev, ctrl->base, &ctrl->drm_aux);
+ ctrl->aux = msm_edp_aux_init(edp, ctrl->base, &ctrl->drm_aux);
if (!ctrl->aux || !ctrl->drm_aux) {
pr_err("%s:failed to init aux\n", __func__);
return -ENOMEM;
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index c04044be3d32..7f38788a6c2b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -1354,6 +1354,7 @@ nouveau_connector_create(struct drm_device *dev,
case DRM_MODE_CONNECTOR_DisplayPort:
case DRM_MODE_CONNECTOR_eDP:
nv_connector->aux.dev = connector->kdev;
+ nv_connector->aux.drm_dev = dev;
nv_connector->aux.transfer = nouveau_connector_aux_xfer;
snprintf(aux_name, sizeof(aux_name), "sor-%04x-%04x",
dcbe->hasht, dcbe->hashm);
diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 15b00a347560..c50c504bad50 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -232,6 +232,7 @@ void radeon_dp_aux_init(struct radeon_connector *radeon_connector)

radeon_connector->ddc_bus->rec.hpd = radeon_connector->hpd.hpd;
radeon_connector->ddc_bus->aux.dev = radeon_connector->base.kdev;
+ radeon_connector->ddc_bus->aux.drm_dev = radeon_connector->base.dev;
if (ASIC_IS_DCE5(rdev)) {
if (radeon_auxch)
radeon_connector->ddc_bus->aux.transfer = radeon_dp_aux_transfer_native;
diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index ea56c6ec25e4..7d7cc90b6fc9 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -719,6 +719,7 @@ int drm_dp_aux_attach(struct drm_dp_aux *aux, struct tegra_output *output)
unsigned long timeout;
int err;

+ aux->drm_dev = output->connector.dev;
err = drm_dp_aux_register(aux);
if (err < 0)
return err;
diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index 59d1fb017da0..7e5e89305028 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -1069,6 +1069,7 @@ static int zynqmp_dp_aux_init(struct zynqmp_dp *dp)

dp->aux.name = "ZynqMP DP AUX";
dp->aux.dev = dp->dev;
+ dp->aux.drm_dev = dp->drm;
dp->aux.transfer = zynqmp_dp_aux_transfer;

return drm_dp_aux_register(&dp->aux);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 1e85c2021f2f..95efe37ea9ca 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1840,6 +1840,8 @@ struct drm_dp_aux_cec {
* @name: user-visible name of this AUX channel and the I2C-over-AUX adapter
* @ddc: I2C adapter that can be used for I2C-over-AUX communication
* @dev: pointer to struct device that is the parent for this AUX channel
+ * @drm_dev: pointer to the &drm_device that owns this AUX channel. Beware, this
+ * may be %NULL before drm_dp_aux_register() has been called.
* @crtc: backpointer to the crtc that is currently using this AUX channel
* @hw_mutex: internal mutex used for locking transfers
* @crc_work: worker that captures CRCs for each frame
@@ -1847,7 +1849,11 @@ struct drm_dp_aux_cec {
* @transfer: transfers a message representing a single AUX transaction
*
* The @dev field should be set to a pointer to the device that implements the
- * AUX channel.
+ * AUX channel. As well, the @drm_dev field should be set to the &drm_device
+ * that will be using this AUX channel as early as possible. For many graphics
+ * drivers this should happen before drm_dp_aux_init(), however it's perfectly
+ * fine to set this field later so long as it's assigned before calling
+ * drm_dp_aux_register().
*
* The @name field may be used to specify the name of the I2C adapter. If set to
* %NULL, dev_name() of @dev will be used.
@@ -1879,6 +1885,7 @@ struct drm_dp_aux {
const char *name;
struct i2c_adapter ddc;
struct device *dev;
+ struct drm_device *drm_dev;
struct drm_crtc *crtc;
struct mutex hw_mutex;
struct work_struct crc_work;
--
2.30.2

Next message: Lyude Paul: "[PATCH v4 05/17] drm/dp: Pass drm_dp_aux to drm_dp_link_train_clock_recovery_delay()"
Previous message: Lyude Paul: "[PATCH v4 04/17] drm/dp: Clarify DP AUX registration time"
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