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drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-…
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…drivers

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 48834e6 ("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>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.9.I3e68fa38c4ccbdbdf145cad2b01e83a1e5eac302@changeid
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Douglas Anderson committed May 3, 2021
1 parent bef236a commit bf73537
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Showing 2 changed files with 200 additions and 53 deletions.
1 change: 1 addition & 0 deletions drivers/gpu/drm/bridge/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -278,6 +278,7 @@ 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

Expand Down
252 changes: 199 additions & 53 deletions drivers/gpu/drm/bridge/ti-sn65dsi86.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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.
Expand All @@ -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;
Expand Down Expand Up @@ -1137,8 +1144,10 @@ 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 */
Expand All @@ -1160,20 +1169,41 @@ 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", },
{},
};

static inline int ti_sn_setup_gpio_controller(struct ti_sn65dsi86 *pdata)
MODULE_DEVICE_TABLE(auxiliary, ti_sn_gpio_id_table);

static struct auxiliary_driver ti_sn_gpio_driver = {
.name = "gpio",
.probe = ti_sn_gpio_probe,
.id_table = ti_sn_gpio_id_table,
};

static int __init ti_sn_gpio_register(void)
{
return 0;
return auxiliary_driver_register(&ti_sn_gpio_driver);
}

static void __exit ti_sn_gpio_unregister(void)
{
auxiliary_driver_unregister(&ti_sn_gpio_driver);
}

#else

static inline int ti_sn_gpio_register(void) { return 0; }
static inline void ti_sn_gpio_unregister(void) {}

#endif

static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata,
Expand Down Expand Up @@ -1225,11 +1255,124 @@ 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", },
{},
};

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,
};

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)
{
Expand Down Expand Up @@ -1279,54 +1422,24 @@ 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[] = {
Expand All @@ -1348,10 +1461,43 @@ 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);

static int __init ti_sn65dsi86_init(void)
{
int ret;

ret = i2c_add_driver(&ti_sn65dsi86_driver);
if (ret)
return ret;

ret = ti_sn_gpio_register();
if (ret)
goto err_main_was_registered;

ret = auxiliary_driver_register(&ti_sn_bridge_driver);
if (ret)
goto err_gpio_was_registered;

return 0;

err_gpio_was_registered:
ti_sn_gpio_unregister();
err_main_was_registered:
i2c_del_driver(&ti_sn65dsi86_driver);

return ret;
}
module_init(ti_sn65dsi86_init);

static void __exit ti_sn65dsi86_exit(void)
{
auxiliary_driver_unregister(&ti_sn_bridge_driver);
ti_sn_gpio_unregister();
i2c_del_driver(&ti_sn65dsi86_driver);
}
module_exit(ti_sn65dsi86_exit);

MODULE_AUTHOR("Sandeep Panda <spanda@codeaurora.org>");
MODULE_DESCRIPTION("sn65dsi86 DSI to eDP bridge driver");
Expand Down

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