[RFC PATCH 4/4] drm/bridge/sii8620: use micro-USB cable detection logic to detect MHL

Andrzej Hajda
2017-09-28T13:08:44Z

From: Maciej Purski <m.purski@samsung.com>

Currently MHL chip must be turned on permanently to detect MHL cable. It
duplicates micro-USB controller's (MUIC) functionality and consumes
unnecessary power. Lets use extcon attached to MUIC to enable MHL chip
only if it detects MHL cable.

Signed-off-by: Maciej Purski <m.purski@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
---
This is rework of the patch by Maciej with following changes:
- use micro-USB port bindings to get extcon, instead of extcon property,
- fixed remove sequence,
- fixed extcon get state logic.

Code finding extcon node is hacky IMO, I guess ultimately it should be done
via some framework (maybe even extcon), or at least via helper, I hope it
can stay as is until the proper solution will be merged.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
---
drivers/gpu/drm/bridge/sil-sii8620.c | 98 ++++++++++++++++++++++++++++++++++--
1 file changed, 95 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
index 5131bfb94f06..6f40cbc2445e 100644
--- a/drivers/gpu/drm/bridge/sil-sii8620.c
+++ b/drivers/gpu/drm/bridge/sil-sii8620.c
@@ -17,6 +17,7 @@

#include <linux/clk.h>
#include <linux/delay.h>
+#include <linux/extcon.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
@@ -25,6 +26,7 @@
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/of_graph.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>

@@ -78,6 +80,10 @@ struct sii8620 {
struct edid *edid;
unsigned int gen2_write_burst:1;
enum sii8620_mt_state mt_state;
+ struct extcon_dev *extcon;
+ struct notifier_block extcon_nb;
+ struct work_struct extcon_wq;
+ int cable_state;
struct list_head mt_queue;
struct {
int r_size;
@@ -2102,6 +2108,78 @@ static void sii8620_cable_in(struct sii8620 *ctx)
enable_irq(to_i2c_client(ctx->dev)->irq);
}

+static void sii8620_cable_out(struct sii8620 *ctx)
+{
+ disable_irq(to_i2c_client(ctx->dev)->irq);
+ sii8620_hw_off(ctx);
+}
+
+static void sii8620_extcon_work(struct work_struct *work)
+{
+ struct sii8620 *ctx =
+ container_of(work, struct sii8620, extcon_wq);
+ int state = extcon_get_state(ctx->extcon, EXTCON_DISP_MHL);
+
+ if (state == ctx->cable_state)
+ return;
+
+ ctx->cable_state = state;
+
+ if (state > 0)
+ sii8620_cable_in(ctx);
+ else
+ sii8620_cable_out(ctx);
+}
+
+static int sii8620_extcon_notifier(struct notifier_block *self,
+ unsigned long event, void *ptr)
+{
+ struct sii8620 *ctx =
+ container_of(self, struct sii8620, extcon_nb);
+
+ schedule_work(&ctx->extcon_wq);
+
+ return NOTIFY_DONE;
+}
+
+static int sii8620_extcon_init(struct sii8620 *ctx)
+{
+ struct extcon_dev *edev;
+ struct device_node *musb, *muic;
+ int ret;
+
+ /* get micro-USB connector node */
+ musb = of_graph_get_remote_node(ctx->dev->of_node, 1, -1);
+ /* next get micro-USB Interface Controller node */
+ muic = of_graph_get_remote_node(musb, -1, 0);
+ of_node_put(musb);
+
+ if (!muic) {
+ dev_info(ctx->dev, "no extcon found, switching to 'always on' mode\n");
+ return 0;
+ }
+
+ edev = extcon_get_edev_by_of_node(muic);
+ of_node_put(muic);
+ if (IS_ERR(edev)) {
+ if (PTR_ERR(edev) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ dev_err(ctx->dev, "Invalid or missing extcon\n");
+ return PTR_ERR(edev);
+ }
+
+ ctx->extcon = edev;
+ ctx->extcon_nb.notifier_call = sii8620_extcon_notifier;
+ INIT_WORK(&ctx->extcon_wq, sii8620_extcon_work);
+ ret = extcon_register_notifier(edev, EXTCON_DISP_MHL, &ctx->extcon_nb);
+ if (ret) {
+ dev_err(ctx->dev, "failed to register notifier for MHL\n");
+ return ret;
+ }
+
+ return 0;
+}
+
static inline struct sii8620 *bridge_to_sii8620(struct drm_bridge *bridge)
{
return container_of(bridge, struct sii8620, bridge);
@@ -2201,13 +2279,20 @@ static int sii8620_probe(struct i2c_client *client,
if (ret)
return ret;

+ ret = sii8620_extcon_init(ctx);
+ if (ret < 0) {
+ dev_err(ctx->dev, "failed to initialize EXTCON\n");
+ return ret;
+ }
+
i2c_set_clientdata(client, ctx);

ctx->bridge.funcs = &sii8620_bridge_funcs;
ctx->bridge.of_node = dev->of_node;
drm_bridge_add(&ctx->bridge);

- sii8620_cable_in(ctx);
+ if (!ctx->extcon)
+ sii8620_cable_in(ctx);

return 0;
}
@@ -2216,9 +2301,16 @@ static int sii8620_remove(struct i2c_client *client)
{
struct sii8620 *ctx = i2c_get_clientdata(client);

- disable_irq(to_i2c_client(ctx->dev)->irq);
+ if (ctx->extcon) {
+ extcon_unregister_notifier(ctx->extcon, EXTCON_DISP_MHL,
+ &ctx->extcon_nb);
+ flush_work(&ctx->extcon_wq);
+ if (ctx->cable_state > 0)
+ sii8620_cable_out(ctx);
+ } else {
+ sii8620_cable_out(ctx);
+ }
drm_bridge_remove(&ctx->bridge);
- sii8620_hw_off(ctx);

return 0;
}
--
2.14.1