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    Subject[PATCH v5 6/6] drm/bridge/sii8620: use micro-USB cable detection logic to detect MHL
    Date
    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>
    ---
    v5: updated extcon API

    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 | 97 ++++++++++++++++++++++++++++++++++--
    1 file changed, 94 insertions(+), 3 deletions(-)

    diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
    index 9e785b8e0ea2..62b0adabcac2 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>

    @@ -81,6 +83,10 @@ 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;
    @@ -2175,6 +2181,77 @@ static void sii8620_init_rcp_input_dev(struct sii8620 *ctx)
    ctx->rc_dev = rc_dev;
    }

    +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_get_next_parent(musb);
    +
    + if (!muic) {
    + dev_info(ctx->dev, "no extcon found, switching to 'always on' mode\n");
    + return 0;
    + }
    +
    + edev = extcon_find_edev_by_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);
    @@ -2307,13 +2384,20 @@ 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;
    }
    @@ -2322,8 +2406,15 @@ static int sii8620_remove(struct i2c_client *client)
    {
    struct sii8620 *ctx = i2c_get_clientdata(client);

    - disable_irq(to_i2c_client(ctx->dev)->irq);
    - sii8620_hw_off(ctx);
    + 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);

    return 0;
    --
    2.16.2
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