[PATCH v4 15/27] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers

Douglas Anderson
2021-04-16T22:41:52Z

Let's use the newly minted aux bus to break up the driver into sub
drivers. We're not doing a full breakup here: all the code is still in
the same file and remains largely untouched. The big goal here of
using sub-drivers is to allow part of our code to finish probing even
if some other code needs to defer. This can solve some chicken-and-egg
problems. Specifically:
- In commit 48834e6084f1 ("drm/panel-simple: Support hpd-gpios for
delaying prepare()") we had to add a bit of a hack to simpel-panel
to support HPD showing up late. We can get rid of that hack now
since the GPIO part of our driver can finish probing early.
- We have a desire to expose our DDC bus to simple-panel (and perhaps
to a backlight driver?). That will end up with the same
chicken-and-egg problem. A future patch to move this to a sub-driver
will fix it.
- If/when we support the PWM functionality present in the bridge chip
for a backlight we'll end up with another chicken-and-egg
problem. If we allow the PWM to be a sub-driver too then it solves
this problem.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

(no changes since v1)

drivers/gpu/drm/bridge/Kconfig | 1 +
drivers/gpu/drm/bridge/ti-sn65dsi86.c | 211 +++++++++++++++++++-------
2 files changed, 158 insertions(+), 54 deletions(-)

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 22a467abd3e9..6868050961a2 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -267,6 +267,7 @@ config DRM_TI_SN65DSI86
select REGMAP_I2C
select DRM_PANEL
select DRM_MIPI_DSI
+ select AUXILIARY_BUS
help
Texas Instruments SN65DSI86 DSI to eDP Bridge driver

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 57bc489a0412..44edcf6f5744 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -4,6 +4,7 @@
* datasheet: https://www.ti.com/lit/ds/symlink/sn65dsi86.pdf
*/

+#include <linux/auxiliary_bus.h>
#include <linux/bits.h>
#include <linux/clk.h>
#include <linux/debugfs.h>
@@ -113,7 +114,10 @@

/**
* struct ti_sn65dsi86 - Platform data for ti-sn65dsi86 driver.
- * @dev: Pointer to our device.
+ * @bridge_aux: AUX-bus sub device for MIPI-to-eDP bridge functionality.
+ * @gpio_aux: AUX-bus sub device for GPIO controller functionality.
+ *
+ * @dev: Pointer to the top level (i2c) device.
* @regmap: Regmap for accessing i2c.
* @aux: Our aux channel.
* @bridge: Our bridge.
@@ -140,6 +144,9 @@
* each other's read-modify-write.
*/
struct ti_sn65dsi86 {
+ struct auxiliary_device bridge_aux;
+ struct auxiliary_device gpio_aux;
+
struct device *dev;
struct regmap *regmap;
struct drm_dp_aux aux;
@@ -1135,8 +1142,10 @@ static const char * const ti_sn_bridge_gpio_names[SN_NUM_GPIOS] = {
"GPIO1", "GPIO2", "GPIO3", "GPIO4"
};

-static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
+static int ti_sn_gpio_probe(struct auxiliary_device *adev,
+ const struct auxiliary_device_id *id)
{
+ struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
int ret;

/* Only init if someone is going to use us as a GPIO controller */
@@ -1158,19 +1167,27 @@ static int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
pdata->gchip.names = ti_sn_bridge_gpio_names;
pdata->gchip.ngpio = SN_NUM_GPIOS;
pdata->gchip.base = -1;
- ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata);
+ ret = devm_gpiochip_add_data(&adev->dev, &pdata->gchip, pdata);
if (ret)
dev_err(pdata->dev, "can't add gpio chip\n");

return ret;
}

-#else
+static const struct auxiliary_device_id ti_sn_gpio_id_table[] = {
+ { .name = "ti_sn65dsi86.gpio", },
+ {},
+};
+
+MODULE_DEVICE_TABLE(auxiliary, ti_sn_gpio_id_table);

-static inline int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
-{
- return 0;
-}
+static struct auxiliary_driver ti_sn_gpio_driver = {
+ .name = "gpio",
+ .probe = ti_sn_gpio_probe,
+ .id_table = ti_sn_gpio_id_table,
+};
+
+module_auxiliary_driver(ti_sn_gpio_driver);

#endif

@@ -1223,11 +1240,128 @@ static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata,
pdata->ln_polrs = ln_polrs;
}

+static int ti_sn_bridge_probe(struct auxiliary_device *adev,
+ const struct auxiliary_device_id *id)
+{
+ struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
+ struct device_node *np = pdata->dev->of_node;
+ int ret;
+
+ ret = drm_of_find_panel_or_bridge(np, 1, 0, &pdata->panel, NULL);
+ if (ret) {
+ DRM_ERROR("could not find any panel node\n");
+ return ret;
+ }
+
+ ti_sn_bridge_parse_lanes(pdata, np);
+
+ ret = ti_sn_bridge_parse_dsi_host(pdata);
+ if (ret)
+ return ret;
+
+ pdata->aux.name = "ti-sn65dsi86-aux";
+ pdata->aux.dev = pdata->dev;
+ pdata->aux.transfer = ti_sn_aux_transfer;
+ drm_dp_aux_init(&pdata->aux);
+
+ pdata->bridge.funcs = &ti_sn_bridge_funcs;
+ pdata->bridge.of_node = np;
+
+ drm_bridge_add(&pdata->bridge);
+
+ return 0;
+}
+
+static void ti_sn_bridge_remove(struct auxiliary_device *adev)
+{
+ struct ti_sn65dsi86 *pdata = dev_get_drvdata(adev->dev.parent);
+
+ if (!pdata)
+ return;
+
+ if (pdata->dsi) {
+ mipi_dsi_detach(pdata->dsi);
+ mipi_dsi_device_unregister(pdata->dsi);
+ }
+
+ kfree(pdata->edid);
+
+ drm_bridge_remove(&pdata->bridge);
+
+ of_node_put(pdata->host_node);
+}
+
+static const struct auxiliary_device_id ti_sn_bridge_id_table[] = {
+ { .name = "ti_sn65dsi86.bridge", },
+ {},
+};
+
+MODULE_DEVICE_TABLE(auxiliary, ti_sn_bridge_id_table);
+
+static struct auxiliary_driver ti_sn_bridge_driver = {
+ .name = "bridge",
+ .probe = ti_sn_bridge_probe,
+ .remove = ti_sn_bridge_remove,
+ .id_table = ti_sn_bridge_id_table,
+};
+
+module_auxiliary_driver(ti_sn_bridge_driver);
+
static void ti_sn65dsi86_runtime_disable(void *data)
{
pm_runtime_disable(data);
}

+static void ti_sn65dsi86_uninit_aux(void *data)
+{
+ auxiliary_device_uninit(data);
+}
+
+static void ti_sn65dsi86_delete_aux(void *data)
+{
+ auxiliary_device_delete(data);
+}
+
+/*
+ * AUX bus docs say that a non-NULL release is mandatory, but it makes no
+ * sense for the model used here where all of the aux devices are allocated
+ * in the single shared structure. We'll use this noop as a workaround.
+ */
+static void ti_sn65dsi86_noop(struct device *dev) {}
+
+static int ti_sn65dsi86_add_aux_device(struct ti_sn65dsi86 *pdata,
+ struct auxiliary_device *aux,
+ const char *name)
+{
+ struct device *dev = pdata->dev;
+ int ret;
+
+ /*
+ * NOTE: It would be nice to set the "of_node" of our children to be
+ * the same "of_node"" that the top-level component has. That doesn't
+ * work, though, since pinctrl will try (and fail) to reserve the
+ * pins again. Until that gets sorted out the children will just need
+ * to look at the of_node of the main device.
+ */
+
+ aux->name = name;
+ aux->dev.parent = dev;
+ aux->dev.release = ti_sn65dsi86_noop;
+ ret = auxiliary_device_init(aux);
+ if (ret)
+ return ret;
+ ret = devm_add_action_or_reset(dev, ti_sn65dsi86_uninit_aux, aux);
+ if (ret)
+ return ret;
+
+ ret = auxiliary_device_add(aux);
+ if (ret)
+ return ret;
+ ret = devm_add_action_or_reset(dev, ti_sn65dsi86_delete_aux, aux);
+
+ return ret;
+}
+
static int ti_sn65dsi86_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
@@ -1277,54 +1411,24 @@ static int ti_sn65dsi86_probe(struct i2c_client *client,

ti_sn65dsi86_debugfs_init(pdata);

- ret = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &pdata->panel, NULL);
- if (ret) {
- DRM_ERROR("could not find any panel node\n");
- return ret;
- }
-
- ti_sn_bridge_parse_lanes(pdata, dev->of_node);
-
- ret = ti_sn_bridge_parse_dsi_host(pdata);
- if (ret)
- return ret;
-
- ret = ti_sn_setup_gpio_controller(pdata);
- if (ret)
- return ret;
-
- pdata->aux.name = "ti-sn65dsi86-aux";
- pdata->aux.dev = dev;
- pdata->aux.transfer = ti_sn_aux_transfer;
- drm_dp_aux_init(&pdata->aux);
-
- pdata->bridge.funcs = &ti_sn_bridge_funcs;
- pdata->bridge.of_node = dev->of_node;
-
- drm_bridge_add(&pdata->bridge);
-
- return 0;
-}
-
-static int ti_sn65dsi86_remove(struct i2c_client *client)
-{
- struct ti_sn65dsi86 *pdata = i2c_get_clientdata(client);
-
- if (!pdata)
- return -EINVAL;
+ /*
+ * Break ourselves up into a collection of aux devices. The only real
+ * motiviation here is to solve the chicken-and-egg problem of probe
+ * ordering. The bridge wants the panel to be there when it probes.
+ * The panel wants its HPD GPIO (provided by sn65dsi86 on some boards)
+ * when it probes. There will soon be other devices (DDC I2C bus, PWM)
+ * that have the same problem. Having sub-devices allows the some sub
+ * devices to finish probing even if others return -EPROBE_DEFER and
+ * gets us around the problems.
+ */

- if (pdata->dsi) {
- mipi_dsi_detach(pdata->dsi);
- mipi_dsi_device_unregister(pdata->dsi);
+ if (IS_ENABLED(CONFIG_OF_GPIO)) {
+ ret = ti_sn65dsi86_add_aux_device(pdata, &pdata->gpio_aux, "gpio");
+ if (ret)
+ return ret;
}

- kfree(pdata->edid);
-
- drm_bridge_remove(&pdata->bridge);
-
- of_node_put(pdata->host_node);
-
- return 0;
+ return ti_sn65dsi86_add_aux_device(pdata, &pdata->bridge_aux, "bridge");
}

static struct i2c_device_id ti_sn65dsi86_id[] = {
@@ -1346,7 +1450,6 @@ static struct i2c_driver ti_sn65dsi86_driver = {
.pm = &ti_sn65dsi86_pm_ops,
},
.probe = ti_sn65dsi86_probe,
- .remove = ti_sn65dsi86_remove,
.id_table = ti_sn65dsi86_id,
};
module_i2c_driver(ti_sn65dsi86_driver);
--
2.31.1.368.gbe11c130af-goog